I am curious about a drive that uses light as its means of propultion.

Is it possible to create? Or is there some law of physics that prevents it from being achieved?

I have just finished reading through my physics books and have been thinking about this.

My knowledge of physics is limited, but still expanding. I wish to know more about a light drive. About the possibilities of getting one to work.

It seems simple enough, but then the calculations are harder to get through.

I may be well out of my league, but I thought that it would be worth asking.

Regards,
J.

I am curious about a drive that uses light as its means of propultion.

Yes, this is possible, because of conservation of momentum; every time you emit a photon to the back of your spacecraft, you eject p = E/c of momentum, where E = hν is the energy of the photon (ν is the frequency of the light and h is Planck's constant). Because of conservation of momentum, the spacecraft gains an equal amount of momentum in the opposite direction. The problem here is that this is a miniscule amount for each photon; you need to have a very, very, very strong light source in order to accelerate any realisticly spacecraft mass.

Using a "light sail" is one way of using photons as propulsion. Unfortunately there appears to be no way to "tack" into the solar wind.

Using a "light sail" is one way of using photons as propulsion. Unfortunately there appears to be no way to "tack" into the solar wind.

The solar wind consists mainly of ejected charged matter (protons); spacecraft using solar wind use the conventional sailing principle of being pushed by a medium colliding with the sail.

Yes, this is possible, because of conservation of momentum; every time you emit a photon to the back of your spacecraft, you eject p = E/c of momentum, where E = hν is the energy of the photon (ν is the frequency of the light and h is Planck's constant). Because of conservation of momentum, the spacecraft gains an equal amount of momentum in the opposite direction. The problem here is that this is a miniscule amount for each photon; you need to have a very, very, very strong light source in order to accelerate any realisticly spacecraft mass.

Hiya Crisp,

My brother has also done physics, when I asked him about this problem, he said that it was impossible to do, but I told him it wan't. I'm glad that I can now show him that my thories were right.

Although, I think that my calculations may need a bit of work.

I have created a design that uses a concave mirror and light absorbant material. The light absorbant material should absorb that momentum from the the reflected light and create a forward force. The mirror will create a "reverse thrust" but the projected light will create an equal forward thrust.

I had been thinking about a laser light, that had plenty of charge. However, the beam may not have enough density, so I have tried to find another source of light that has a much higher density. Once I find out the density that the required light would need to be for the photon count, it should be poxsible.





Using a "light sail" is one way of using photons as propulsion. Unfortunately there appears to be no way to "tack" into the solar wind.

I like the light sail, but it is too hard to use. Solar wind is one thing that I had forgotten to take into account. that may cause a shift in the way the device needs to be shaped.
Thanks! :cool:


The solar wind consists mainly of ejected charged matter (protons); spacecraft using solar wind use the conventional sailing principle of being pushed by a medium colliding with the sail.

How big would the sail need to be to collect enough matter to create a forward accelleratino great enough to be noticed quickly?

I gather it depends on the density of the particle stream, but how can the matter be caught in such a way that it is not reflected or absorbed, but allowed to pass through to allow no distortion in the quantum flux of the energy pattern? *(Does this question make sense?)* :confused:

Thanks very much.

Regards,
J.

If you do the calculations I think you'll find that it's impossible to create any appreciable thrust with anything like our current technology. The amount of light that would have to be used to propel any substantially sized object is almost inconceivable.

If you do the calculations I think you'll find that it's impossible to create any appreciable thrust with anything like our current technology. The amount of light that would have to be used to propel any substantially sized object is almost inconceivable.

Hello Nasor,

You are correct, there is no appreciable thrust with primitive technology like what we have access to. It is not an inconcieveable amount. It's the density of the particles that matters the most. A spectrum that is not visible:eek: to the naked eye has different densities.

If one has a very high density and is accessable by current technology, then it is possible.

What size of an object would you be talking about? A "Galaxy sized Star Ship" from Star Trek or a Shuttle that we send up into space? Maybe the size of a house .?.

I am not talking about using it within the atmosphere, only in a void. Otherwise it would not work the correct way, and as you say, would produce a miniscule amout of Newtons to any object.

Regards,
J.

Keep in mind that any design in which the ship absorbs its own emitted light will result in a net momentum change of zero.

You are correct, there is no appreciable thrust with primitive technology like what we have access to. It is not an inconcieveable amount. It's the density of the particles that matters the most.It's the energy of the photons that matter. A single x-ray photon would have far more 'pushing power' than several infra-red photons, for example. Light doesn't really have a density, since it has no mass. What size of an object would you be talking about? A "Galaxy sized Star Ship" from Star Trek or a Shuttle that we send up into space? Maybe the size of a house .?Well, let's put it this way; if you continuously outputted light at a rate of a megawatt (which you would need a healthy-sized nuclear reactor to power - like the big ones that power cities, not the small ones that power navy ships and space stations) it would take 5 hours to accelerate an object massing only 1 kg to 1 meter/second.

Keep in mind that any design in which the ship absorbs its own emitted light will result in a net momentum change of zero.
Hello Hyper,

Not nessicarily. It all depends on when it is absorbed, and how. ;)

Regards,
J.


It's the energy of the photons that matter. A single x-ray photon would have far more 'pushing power' than several infra-red photons, for example. Light doesn't really have a density, since it has no mass. Well, let's put it this way; if you continuously outputted light at a rate of a megawatt (which you would need a healthy-sized nuclear reactor to power - like the big ones that power cities, not the small ones that power navy ships and space stations) it would take 5 hours to accelerate an object massing only 1 kg to 1 meter/second.

Hiya Nasor,

Ahh, good point. Light does have a mass. But it is extremely minute. If it didn't have a mass, then it couldn't move anything or have any force acting upon it, and thus, a black hole would not affect it. Thus, light does have mass.

A simple power convertion could do that for you, so a small nuclear reactor could do the trick. With one unit, yes, but I would be using about 20 units to accelerate a ship. It would weigh about 2 tonnes, It should only take a few centuries to move it. :D

My calculations appear to need a little bit of work, so I shall do that and return with my findings in a day or so.

Thanks Nasor! :cool:

Regards,
J.

jolonar, light has no mass. it has momentum.

Ahh, good point. Light does have a mass. But it is extremely minute. If it didn't have a mass, then it couldn't move anything or have any force acting upon it, and thus, a black hole would not affect it. Thus, light does have mass.Nope, light has no mass - only energy and momentum. It isn't necessary for something to have mass to be affected by gravity. A simple power convertion could do that for you, so a small nuclear reactor could do the trick.I don't understand what you mean by this.

Hello Hyper,

Not nessicarily. It all depends on when it is absorbed, and how. ;)

A ship that absorbs its own emitted light is a closed system. If it starts with zero momentum, it will always have zero momentum.

How about what a good fusion reactor can create in the way of a few hundred gigawatts of beamed energy, somewhat of photon dump-trucks loaded with as much mass as possible. In which case we may need to know about the following;

What's the realistic Terminal Velocity of Space Travel?

I'm speaking of actual physical stuff, such as for a craft that's displacing 1000 m3, whereas such, how fast is fast enough?

Obviously at 3e8 m/s * 1e3 = 3e11 m3/s being displaced, and obviously that's either expecting way too much, or of simply requiring way more energy than any 1000 m3 craft could possibly muster.

It takes energy as to displace your way through that many m3/s, through a substance that's perhaps containing as many as 1e6 atoms/m3.

So, of what's possible without our having to utilize anything in the twilight zone?

Can the likes of a sufficient laser/plasma cannon give us 50% Light Speed?

If so, then what's the amount of energy/m3 as for driving and sustaining 50% LS?

Since many of you keep insisting that you know all there is to know about such things, perhaps you'd care as to share in the notions of our capability of transporting ourselves through said expanse of space, or otherwise as to utilizing that of a laser beam of creating those spinning atomic Oort zones reaching all the way out to a given point of nullification, such as the 0.7 light year distant one that's situated between us and Sirius, and from that established photon conduit or waveguide we might then utilize Dr. Wang's 310X packets as to communicate with the likes of whomever is still associated with Sirius.

Or isn't interstellar communications permitted by the space-time-continuum of this forum?

Actually, using a light beam for rocket propulsion would be very efficient, since specific impulse increases as the reaction "mass" is more and more finely divided. In fact, I think that photonic propulsion is probably the only means of rocket propulsion which would enable one to reach even the nearest stars in a reasonable amount of time.

One technical challenge would be that the light beam would have to be extraordinarily intense, and any equipment through which it passed on its way out of the ship would be vaporized instantly if it were not almost perfectly reflective.

Well, let's put it this way; if you continuously outputted light at a rate of a megawatt (which you would need a healthy-sized nuclear reactor to power - like the big ones that power cities, not the small ones that power navy ships and space stations)

Naval vessels have reactors that are many tens of megawatts (thermal). Land-based plants are several hundred MWth, up to a thousand MWth or so.

What's the realistic Terminal Velocity of Space Travel?

I'm speaking of actual physical stuff, such as for a craft that's displacing 1000 m3, whereas such, how fast is fast enough?

Obviously at 3e8 m/s * 1e3 = 3e11 m3/s being displaced, and obviously that's either expecting way too much, or of simply requiring way more energy than any 1000 m3 craft could possibly muster.

It takes energy as to displace your way through that many m3/s, through a substance that's perhaps containing as many as 1e6 atoms/m3.A couple of point here.

The terminal velocity of your ship will depend mainly on its cross-section (the area of the ship that faces the direction of motion). The volume doesn't really matter. Imagine the difference in wind resistance between a frisbee that's traveling through the air normally with its edge facing the direction of motion vs. a frisbee that's traveling through the air with its wide, flat surface facing along the direction of motion – both frisbee disks have the same volume, but one will have far more drag.

The density of interstellar space is only about 1 proton/cubic meter. Obviously that would change once you got in closer to a solar system, but for the vast majority of an interstellar ship's journey 'space drag' wouldn't be a problem.

Assuming your 1000 m^3 craft was a cube that was 10 meters on each side, then traveling at the speed of light through interstellar space it would only have to displace 100 m^2 * 3*10^8 m/s = 3*10^10 cubic meters of space/second. At a density of 1 proton/ m^3, that would mean the ship would displace 3*10^10 m^3 / 6.022*10^23 g/m^3, which would only be about 5 * 10^-11 kg/second.

Even if you wanted your ship to actually collect all that mass (rather than simply knocking it out of the way) it would only require about 2.2 megawatts of power, which would presumably be easy for such an advanced ship.

So space drage really shouldn't be a problem.

Thanks for the correction, swansont.

jolonar, light has no mass. it has momentum.

Light does have mass. I can assure you of that. Although, noone has been able to register the mass because it is so minute....

Nope, light has no mass - only energy and momentum. It isn't necessary for something to have mass to be affected by gravity. I don't understand what you mean by this.

The mass of light is too small to be registered on any current earthly device.
I mean, "power convertion" Get the powersource, and increase the voltage to a couple of thousand megawatts.

A ship that absorbs its own emitted light is a closed system. If it starts with zero momentum, it will always have zero momentum.

I beg to differ. It is a closed system, and it's light is absorbed. However, the way it is absorbed provides forwards momentum.

How about what a good fusion reactor can create in the way of a few hundred gigawatts of beamed energy, somewhat of photon dump-trucks loaded with as much mass as possible. In which case we may need to know about the following;





What's the realistic Terminal Velocity of Space Travel?


How fast do you want to go?


I'm speaking of actual physical stuff, such as for a craft that's displacing 1000 m3, whereas such, how fast is fast enough?


Fast enough is about one astronomical unit in maybe one hour. Probably more though.


Obviously at 3e8 m/s * 1e3 = 3e11 m3/s being displaced, and obviously that's either expecting way too much, or of simply requiring way more energy than any 1000 m3 craft could possibly muster.


If you use a phase 3 nuclear reactor you could in fact double the power output by inducing a stray thermo nuclear photon with a large amount of exposure of photonic energy from the sun.


It takes energy as to displace your way through that many m3/s, through a substance that's perhaps containing as many as 1e6 atoms/m3.


I am not thinking of using this inside the atmosphere. It is for Void use only, this is because of the small amount of acceleration the craft will use.


So, of what's possible without our having to utilize anything in the twilight zone?

There is no such this as the twilight zone. Only other dimensions exist of parralell reality. Some the same, some different. We are always switching our path through realities, even though we are still sitting in the one reality time space, we are in fact moving through to another reality.


Can the likes of a sufficient laser/plasma cannon give us 50% Light Speed?


Yes.


If so, then what's the amount of energy/m3 as for driving and sustaining 50% LS?

The speed of light is not calulatable, so I shall give you a rough idea soon enough.


Since many of you keep insisting that you know all there is to know about such things, perhaps you'd care as to share in the notions of our capability of transporting ourselves through said expanse of space, or otherwise as to utilizing that of a laser beam of creating those spinning atomic Oort zones reaching all the way out to a given point of nullification, such as the 0.7 light year distant one that's situated between us and Sirius, and from that established photon conduit or waveguide we might then utilize Dr. Wang's 310X packets as to communicate with the likes of whomever is still associated with Sirius.

Interesting. I will have to look up about this. Thanks!


Or isn't interstellar communications permitted by the space-time-continuum of this forum?

The S.T.C. has many ways of utilizing communications through its existance and expance. This forum allows it because it is part of physics.

Many thanks.

Regards,
J.

A couple of point here.

The terminal velocity of your ship will depend mainly on its cross-section (the area of the ship that faces the direction of motion). The volume doesn't really matter. Imagine the difference in wind resistance between a frisbee that's traveling through the air normally with its edge facing the direction of motion vs. a frisbee that's traveling through the air with its wide, flat surface facing along the direction of motion – both frisbee disks have the same volume, but one will have far more drag.


There will be very little of the craft exposed to the direction of motion. It's surface will be as smooth as it possibly can be. But that won't be an ideal surface, it will have a sharp edge facing forward for optimal motionn of particles around the body.


The density of interstellar space is only about 1 proton/cubic meter. Obviously that would change once you got in closer to a solar system, but for the vast majority of an interstellar ship's journey 'space drag' wouldn't be a problem.


Thanks for that. Now i can fix my calculations!! :D


Assuming your 1000 m^3 craft was a cube that was 10 meters on each side, then traveling at the speed of light through interstellar space it would only have to displace 100 m^2 * 3*10^8 m/s = 3*10^10 cubic meters of space/second. At a density of 1 proton/ m^3, that would mean the ship would displace 3*10^10 m^3 / 6.022*10^23 g/m^3, which would only be about 5 * 10^-11 kg/second.


Ahh.... that gives me an idea..... :confused:
Thanks!


Even if you wanted your ship to actually collect all that mass (rather than simply knocking it out of the way) it would only require about 22 megawatts of power, which would presumably be easy for such an advanced ship.


Yes. But with the tech and funds I have abailable to me, it shouldn't take too long for me to build a model. But the real thing would take years, maybe even centuries to have the tech for my designs.


So space drage really shouldn't be a problem.

Excellent.

Thanks again Nasor. Does your head ever get warmed up with these calculations, or are you running cold while doing this? ;)

Regards,
J.

The mass of light is too small to be registered on any current earthly device.Well, you're entitled to your opinion, but all available scientific evidence indicates that light does not have mass. It isn't just a matter of us not having instruments sensitive enough to detect it; according to everything we know about physics, light can't have mass.I mean, "power convertion" Get the powersource, and increase the voltage to a couple of thousand megawatts.Careful, voltage is not measured in megawatts. Watts (or megawatts) are units of power. It tells you how much energy your power source can put out in a given amount of time. Unlike voltage (which can be easily changed) this isn't really something that you can really change, unless you want to get a different power source. Does your head ever get warmed up with these calculations, or are you running cold while doing this?I have a TI-89 calculator that laughs at pretty much any math problem that you throw at it. If you're seriously studying math, science, or engineering, I can't recommend it strongly enough. Actually maybe not if you're studying math...after a while it ruins your ability to do calculus...but that's a small price to pay, in my opinion.

Light does have mass. I can assure you of that. Although, noone has been able to register the mass because it is so minute....

Hi Jolonar,
Why are you so sure that light has mass?
Assurances are worthless without sound reasoning and/or observations to back them up.

Afterthought:
I suppose that assurances backed by authority also have some limited worth.

Well, you're entitled to your opinion, but all available scientific evidence indicates that light does not have mass. It isn't just a matter of us not having instruments sensitive enough to detect it; according to everything we know about physics, light can't have mass.

Light does have a mass, otherwise, it would move at an infintessimal speed. And that's according to physics. Both rules are correct, but without mass, it should move at an infintessimal speed for there is nothing that can slow it down. No mass = no friction.


Careful, voltage is not measured in megawatts. Watts (or megawatts) are units of power. It tells you how much energy your power source can put out in a given amount of time. Unlike voltage (which can be easily changed) this isn't really something that you can really change, unless you want to get a different power source.

Sorry, my mistake. It's just too damn cold down here.


I have a TI-89 calculator that laughs at pretty much any math problem that you throw at it. If you're seriously studying math, science, or engineering, I can't recommend it strongly enough. Actually maybe not if you're studying math...after a while it ruins your ability to do calculus...but that's a small price to pay, in my opinion.

heh heh heh..... I also laugh at pretty much any math problem anyone throws at me. Then I get a paper cut. And after all that, I have to solve it!

I admit theat they are good, but they pale in comparison to the brain. I found that it helped my calculus in some cases, because I could change a number and vualah, the answer was there, staring me in the face. It really helped in Specialist Maths. Calculous Shmaculous, it's somthing that you can do without. If something else can do it, why do it ourselves?

Maths is hard unless you get help. My mother is a maths teacher. And I struggled through Specialists. But, since then, I have done harder problems in real life than in school.

I hate School. I really do, they tell you things that you already know, and that's it. It's too easy!

Well, I need to do some calculations.

Regards,
J.

I beg to differ. It is a closed system, and it's light is absorbed. However, the way it is absorbed provides forwards momentum.

Hi Jolonar,
It's a fascinating idea, but you'll need a pretty convincing argument backed by sound theory to persuade people that momentum does not have to be conserved in a closed system.

Light does have a mass, otherwise, it would move at an infintessimal speed.

Do you mean infinite speed? Infinitesimal (http://dictionary.reference.com/search?q=infinitesimal) means infinitely small.

And that's according to physics.
Can you back up that assertion?

Hiya Pete,

It's a fascinating idea, but you'll need a pretty convincing argument backed by sound theory to persuade people that momentum does not have to be conserved in a closed system.

Thanks, I realise that I need the theories to be sound, but I need the device made to make it sound. Anyhow, why would momentum need to be conserved within a closed device?

Do you mean infinite speed? [url=http://dictionary.reference.com/search?q=infinitesimal]Infinitesimal means infinitely small.

Can you back up that assertion?[/QUOTE]
Thanks Pete! Yes, that's what I mean.

Yes, I can. If light has no mass, then why does it take 8 minutes to get from the Sun to the Earth?? It travels at an extremely fast rate I admit, but it is not an Infinitesimal ;) speed. For it is calculatable.

Regards,
J.

You appear to be under the impression that zero mass implies infinite speed.
Why?




Let's explore this...

You appear to be under the impression that zero mass implies infinite speed.
Why?




Let's explore this...

Well, if something has no mass, then no force can act upon it, not even the atmosphere because it has no size from no mass, theoretically it shouldn't exist if it has no mass. Mass is required for something to exist. If an atom had 0 mass, then it wouldn't exist.

It's as simple as that.

Well, if something has no mass, then no force can act upon it, not even the atmosphere because it has no size from no mass, theoretically it shouldn't exist if it has no mass. Mass is required for something to exist. If an atom had 0 mass, then it wouldn't exist.

It's as simple as that.Nope, you just made that up. Mass is simply one of many properties that something can either have or not have. It's not true that something must have mass in order to be acted upon; a magnetic field, for example, has no mass and can be effected by all sorts of thing.

If you don't want to take our word for it, check out this page from the physics department of the university of california http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html .

Mass is required for something to exist.
Did you make that up?

I won't address that assertion directly, because it seems to be to be more philosophical that physical.

However, I will point out that mass and energy are two sides of the same thing, so much so that the term "mass-energy" is used in situations where the difference is irrelevant.

I therefore suggest that an entity with energy and no mass (eg light) is at some level not essentially different to an entity with mass and no energy, or with both mass and energy.

Nope, you just made that up. Mass is simply one of many properties that something can either have or not have. It's not true that something must have mass in order to be acted upon; a magnetic field, for example, has no mass and can be effected by all sorts of thing.

If you don't want to take our word for it, check out this page from the physics department of the university of california http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html .

I did not make that up. A magnetic field is the result of a "magnet" that's all. it is not actually there, it passes through objects because it has no mass. Light on the other had creates shadows! Thus, it has a mass, thus it itself exists!

Right. So, then, a light drive is impossible?

Did you make that up?
No, I did not.
I won't address that assertion directly, because it seems to be to be more philosophical that physical.
It's both actually.
However, I will point out that mass and energy are two sides of the same thing, so much so that the term "mass-energy" is used in situations where the difference is irrelevant.
Yes, but energy has mass. In theory.
I therefore suggest that an entity with energy and no mass (eg light) is at some level not essentially different to an entity with mass and no energy.
You posted this just before I posted my post, so, you may read my post and then you can reply regarding this matter if you wish, unless it explains it.

Regards,
J.

I did not make that up. A magnetic field is the result of a "magnet" that's all. it is not actually there, it passes through objects because it has no mass. Light on the other had creates shadows! Thus, it has a mass, thus it itself exists!

Right. So, then, a light drive is impossible?No, a light drive is quite possible because light has momentum, even though it has no mass.

I don't really want to get in an argument with you over whether or not light has mass, but if you check any textbook or university physics web page they will tell you the same thing I'm telling you.

If you didn't make it up, then where did it come from?
Is it your own deduction (to me, this is much the same as making it up unless accompanied by a rigorous referenced argument)?
Is it from a reliable source?
Yes, but energy has mass. In theory.
No!
Energy and mass are the same thing at a deeper level, but it is a misrepresentation of the theory to say that energy has mass.

I suggest that mass is not required for something to exist.
It may or may not be true that mass-energy (mass or energy or both) is necessary for existence.

I suggest that light has energy and momentum, but no mass.

You may wish to review some fundamentals of relativity before continuing, as you seem to be unaware or misinformed of current understanding on this issue.

Hyperphysics (http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/relmom.html)
Usenet Physics FAQ (http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html)

No, a light drive is quite possible because light has momentum, even though it has no mass.

Okay... Well, if light has no mass then why does it create shadows when it hits an object? If it has no mass it should just go through.

I don't really want to get in an argument with you over whether or not light has mass, but if you check any textbook or university physics web page they will tell you the same thing I'm telling you.

I know, but it doesn't stand up to the laws of physics and the universe.

I'm just trying to understand where I was taught wrong, if I was at all.

That's all, I'm not trying to create a huge arguement, I just don't understand why mass or energy is not required to make something exist.

Regards,
J.

Thanks Pete,

I will read up some more to see what I can find out. Then I'll look back at reality and compare. They'll probably match for all I know. It's not like I have the blueprints for an Agnomat Hydro Generator in my brain, or even the Hovercar that goes anywhere. Or even the blackprints for a Universal Lingual MonSpace Transmitter.

Anyhow. I will get back to you about my sources, I do not know if they want their names exposed to the general public. I may be able to persuade them to let me disclose their names to your elite mind.

I shall read up some more, then get back to the light drive.

Many thanks.

Regards,
J.

P.S. While I'm not working on the Light Drive I will work on the Agnomat Hydro Generator.

If you didn't make it up, then where did it come from?
Is it your own deduction (to me, this is much the same as making it up unless accompanied by a rigorous referenced argument)?
Is it from a reliable source?

No!
Energy and mass are the same thing at a deeper level, but it is a misrepresentation of the theory to say that energy has mass.

I suggest that mass is not required for something to exist.
It may or may not be true that mass-energy (mass or energy or both) is necessary for existence.

I suggest that light has energy and momentum, but no mass.

You may wish to review some fundamentals of relativity before continuing, as you seem to be unaware or misinformed of current understanding on this issue.

Hyperphysics (http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/relmom.html)
Usenet Physics FAQ (http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html)

Okay... Well, if light has no mass then why does it create shadows when it hits an object? If it has no mass it should just go through.



I know, but it doesn't stand up to the laws of physics and the universe.

I'm just trying to understand where I was taught wrong, if I was at all.

That's all, I'm not trying to create a huge arguement, I just don't understand why mass or energy is not required to make something exist.

Regards,
J.Your mistake is in assuming that something must have mass to exist or interact with the physical world. I can see why this would make intuitive sense to you, but it just isn't the case. In our everyday lives we only usually encounter things that have mass (except for light of course, but we don't really experience light in the same way that we experience physical objects) so it's tempting to assume that everything must have mass, but that's not the way the universe works.

Your mistake is in assuming that something must have mass to exist or interact with the physical world. I can see why this would make intuitive sense to you, but it just isn't the case. In our everyday lives we only usually encounter things that have mass (except for light of course, but we don't really experience light in the same way that we experience physical objects) so it's tempting to assume that everything must have mass, but that's not the way the universe works.

I see your point.

I experience light the same way I do everything else. I feel it on my skin. I feel it pushing against me. I can touch it, but can't hold it.

I can see the movement of the light. I hear the light. You can only see me because of light.

Light binds us all. Without light, you are blind.

Regards,
J.

For massive objects, momentum is: m*v / sqrt(1 - v^2/c^2)

If light has mass, then it has infinite momentum. I hope your light ship has dang good brakes.

For massive objects, momentum is: m*v / sqrt(1 - v^2/c^2)

If light has mass, then it has infinite momentum. I hope your light ship has dang good brakes.

Thanks, that will be useful for expanding my formula more! :)
heh heh heh.... Oh, no brakes are nessicary, just reverse the direction of the thrusters and light drives to stop.

Regards,
J.

Anyhow, why would momentum need to be conserved within a closed device?


F=dP/dt

If there is no net external force, momentum cannot change.

If it were otherwise, you could pick yourself up by your bootstraps.

Light does have mass. I can assure you of that. Although, noone has been able to register the mass because it is so minute....
Not when I went to school. Cite your source.

F=dP/dt

If there is no net external force, momentum cannot change.

If it were otherwise, you could pick yourself up by your bootstraps.

You can't pick yourself up by your bootstraps because you are all one object!

Not when I went to school. Cite your source.

At school, no, they do not know about the mass of light. No one does. I know it has mass because I can feel the light, I can see the light.

If you do not believe me, fin a device that can measure the mass of objects, and get a piece of light in a void and measure its minute mass. It's that simple.

At school, no, they do not know about the mass of light. No one does. I know it has mass because I can feel the light, I can see the light.

If you do not believe me, fin a device that can measure the mass of objects, and get a piece of light in a void and measure its minute mass. It's that simple.

I tried weighing some photons on my bathroom scale, but the dang things won't stay put!

I tried weighing some photons on my bathroom scale, but the dang things won't stay put!

Heh, heh, heh..... Funny....But your scales weren't sensitive enough!

And you can't weigh photons like that. Anyhow, I was talking Mass, not weight! ;)

Try measuring their mass only. If you use a device to do that then you can catch them! I think.... :confused:

Anyhow, try again when they've run around for a bit, they should fall asleep after that! :D

Regards,
J.

For massive objects, momentum is: m*v / sqrt(1 - v^2/c^2)

If light has mass, then it has infinite momentum. I hope your light ship has dang good brakes.


So, Light has infinite momentum then?

Cool!

So, Light has infinite momentum then?

Cool!

No, it's p=E/c

Light has no rest mass.

At school, no, they do not know about the mass of light. No one does. I know it has mass because I can feel the light, I can see the light.

If you do not believe me, fin a device that can measure the mass of objects, and get a piece of light in a void and measure its minute mass. It's that simple.
I you have some kind of background in physics, I will let stand your assertion, even though essentially all physicists in the world disagree with your statement that light has mass. Do you?

Getting into the conversation, would it be any help to suggest one of Einstein ;s calculations or determinations regarding light, he mentioned that light excerts a force of 4.2 pounds a cm. sq. i belive thats correct.

Thanks. I appreciate that. Can you confirn that light has mass? For that is my belief, but no-one else believes me!


I assume that a light drive engine would be based on a laser, or the induction of light from the enviroment and its redistribution to a point of focus by some bodie or mass that inducts light, prehaps a vaccum.

DwayneD.L.Rabon
Thank you for confirming. That is what I have been looking for. Interesting. I shall look into that. I had not thought about the redistribution.

Thanks!



No, it's p=E/c

Light has no rest mass.
I beg to differ! I 'know' for a fact that light has mass. (Physics 101)




I you have some kind of background in physics, I will let stand your assertion, even though essentially all physicists in the world disagree with your statement that light has mass. Do you?

Yes, I do have a background in Physics. Not as much as you though.

My father, my brother and some others say that light has mass. How can someone with a PhD or even more say something that isn't true. For light has mass. minute amount, but it does have it!



I stand by my statement "Light has Mass"!
There is no doubt about that!
Am I smarter than those peoplee with PhD's, or is it just that I know something that they don't?

Regards,
J.

Jolonar, can you provide a reference of some kind for your so far unsupported assertion?

"My PhD Dad says so" doesn't cut it, because for this question, some context is necessary.

Did you bother to read the link I so helpfully provided earlier?

Does light have mass (http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html) (Usenet Physics FAQ)

My father, my brother and some others say that light has mass. How can someone with a PhD or even more say something that isn't true. For light has mass. minute amount, but it does have it!
Do they have PhDs in Physics?

Jolonar, can you provide a reference of some kind for your so far unsupported assertion?

"My PhD Dad says so" doesn't cut it, because for this question, some context is necessary.

Did you bother to read the link I so helpfully provided earlier?

Does light have mass (http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html) (Usenet Physics FAQ)

Thanks for the link.
My father doesn't have a PhD.
If you want to know the truth about light, look in a book!
I looked at the link. Photons have mass!


Do they have PhDs in Physics?
No.



Regards,
J.

Only by odd interpretations.
Photons have relativistic mass. This is not considered to be real mass.

Only by odd interpretations.
Photons have relativistic mass. This is not considered to be real mass.
Okay, thanks.

I may be wrong about the mass issue, for I might not have been taught the difference between the types of masses.

However, my statement holds true. "Light has mass".

Regards,
J.

Okay, thanks.

I may be wrong about the mass issue, for I might not have been taught the difference between the types of masses.

However, my statement holds true. "Light has mass".

Regards,
J.
Well, I think pretty much every physicist in the world disagrees. I hope that your background in the field is such as to make it realistic for you to challenge the world's scientists.

Well, I think pretty much every physicist in the world disagrees. I hope that your background in the field is such as to make it realistic for you to challenge the world's scientists.

No, I am not that into Physics to challenge the world.

Maybe later I shall tell them.

Regards,
J.

If lasers can exist then Yes, Light drive is possible even today. The laser beams we create today doesn’t disintegrate the source device. If we create a huge array of lasers firing in one direction …

When we get thunder lightning we get powerful light. Can we use the same technique for creating fantastic amount of light, Kinda converting matter into direct light ?

It is said that the speed of light always remains constant relative to all speeding objects, according to that we may be able to travel faster that speed of light with the help of light drive. That’s because even at 99.99 % speed of light the light drive will be ejecting light at light speed in the opposite direction, Now as the light is being emitting in the other direction there is no question of that light breaking the light speed barrier, hope I am wrong ?

If U wana prove if light has mass then : Take a Light Drive, measure its weight, then zoom around the universe, come back and weight the LD again, If light has no mass then there should be no change in weight , what do U think, please correct me ?


Nasor:
If U think something can exist without being particles then U must also explain how something that is not a particle interacts with a particle ?

If lasers can exist then Yes, Light drive is possible even today. The laser beams we create today doesn't disintegrate the source device. If we create a huge array of lasers firing in one direction
Thanks! This is helping me alot. But it changes my designs quite a bit in the size department!

When we get thunder lightning we get powerful light. Can we use the same technique for creating fantastic amount of light, Kinda converting matter into direct light ?
Yes, that's right!!!! Lightning is a spark of electricity created from a posively negatively charged cloud. To re create in a closed space, it would kinda be like the spark of an arklight, but on a larger scale. That may work better.

It is said that the speed of light always remains constant relative to all speeding objects, according to that we may be able to travel faster that speed of light with the help of light drive. That's because even at 99.99 % speed of light the light drive will be ejecting light at light speed in the opposite direction, Now as the light is being emitting in the other direction there is no question of that light breaking the light speed barrier, hope I am wrong ?
With a light drive, you will not be able to break the speed of light. But with 2 light drives, then you may get to the speed of light. But then you would start to slow down because the light inside the drive will be almost motionless. So I would say that the speed of light is unreachable using a light drive!

If U wana prove if light has mass then : Take a Light Drive, measure its weight, then zoom around the universe, come back and weight the LD again, If light has no mass then there should be no change in weight , what do U think, please correct me ?
Maybe.... That may work, but it may not since the particles are absorbed to give a forward thrust. Their kinetic energy is converteed into heat in the drive itself, so it would need to be cooled, thus external forces ware at work. The weight would be different as soon as the cooling device was turned on.


Nasor:
If U think something can exist without being particles then U must also explain how something that is not a particle interacts with a particle ?

Thank you for this explanation.
Nope, light has no mass - only energy and momentum. It isn't necessary for something to have mass to be affected by gravity.
When Nasor said this, I thought of black holes. If light had no mass it would travel at an infinite speed! Thus, black holes could not affect it!!!
Is this true RawThinkTank?

If anyone can understand this, please, tell me. Bucause, either I am right, or I have not understood something correctly, or else the laws of physics are totally skrewed up.

Regards,
J.

When Nasor said this, I thought of black holes. If light had no mass it would travel at an infinite speed! Thus, black holes could not affect it!!!


No, things without mass travel at c. Why do you think the speed would be infinite?

If I am correct there are some serious problems with traveling faster than light speed, such as tendancy to gravitate to centers of mass such as planets and suns ect....

Yes, they are factors that can not be calculated easily because of their tendancy to move around the systems, and withing the universes.


Some other odd things may also occur such as the continous formation of mass, i.e. lights transfromation in to mass, and the event of nuclear decay. this may not actually occur at light speed but at around twice the speed of light. just some possiblities.

Yes, I 'd have to agree. However, I do not think that a light drive could go faster than the speed of light because it uses light itself to move. Thus it can't even reach the speed of light! So I'd say were pretty safe with that one!


traveling at light speed may be safer than faster than light speed.

Why would you say that?



It is very interesting!!!

DwayneD.L.Rabon
Yes, I'd tend to agree.


No, things without mass travel at c. Why do you think the speed would be infinite?

No friction, no slowing down, no loss of energy or momentum!


Regards,
J.

If lasers can exist then Yes, Light drive is possible even today. The laser beams we create today doesn’t disintegrate the source device. If we create a huge array of lasers firing in one direction …

When we get thunder lightning we get powerful light. Can we use the same technique for creating fantastic amount of light, Kinda converting matter into direct light ?The problem is that you get very little 'push' in terms of energy expended from a light drive. Even if we had a magic light bulb that could turn any amount of energy into light with no loss of efficiency, we don't have any power sources strong enough to impart a useful acceleration on a substantially massive object with a light drive.

And yes, we can make lights based on shooting a big spark through gas. It's called an arc light, and so far as I know they're the brightest sustained source of light that humans currently make.

The problem is that you get very little 'push' in terms of energy expended from a light drive. Even if we had a magic light bulb that could turn any amount of energy into light with no loss of efficiency, we don't have any power sources strong enough to impart a useful acceleration on a substantially massive object with a light drive.

Wouldn't a nuclear reactor be powerful enough to create a useful accelleration? Not too big of course. Or what about a Plasma core generator?


And yes, we can make lights based on shooting a big spark through gas. It's called an arc light, and so far as I know they're the brightest sustained source of light that humans currently make.

Aren't arc lights very bad for the eyes? They can cause blindness very easily.

Really? The brightest sustained source of light? Nice!

Maybe it will be easier to do than I had thought.

Regards,
J.

No friction, no slowing down, no loss of energy or momentum!


That doesn't mean infinite speed. Light is an electromagnetic wave, and space has a finite permittivity and permeability for electric and magnetic fields, respectively.

If light had no mass it would travel at an infinite speed!

Light would only travel at the speed it is ejected from an electron even if it did not had any mass.

But if it has no mass then Light Drive should be able propel us at any speeds.

And yes if we can unlock the secret of why light is instigated at its speed then we may know how to over come light speed barrier.

Thus, black holes could not affect it!!!

That depends on speed of gravity.

… either I am right, or I have not understood something correctly, or else the laws of physics are totally skrewed up.

U r right maths is gone astray hence the illusion of physics being so.

Wouldn't a nuclear reactor be powerful enough to create a useful accelleration? Not too big of course.The most sophisticated reactor currently available for spacecraft is the SAFE-400, developed at the Los Alamos National Laboratory a few years ago. It masses just 512 kg and can produce 100 kW of electricity.

Even if all of the energy was converted perfectly into light, it would accelerate at about 6.5*10^-7 m/s. At that rate it would take 14.6 million years to reach the speed of light. And that's only considering the mass of the reactor, ignoring the mass of the rest of the ship.

Is it just me, or did that not make any sense whatsoever?

It's not you.

[ the enviorment that we see would become as invisable, and less visable the faster we travel. ]

Dwayne D.L.Rabon[/QUOTE]



youre getting at a "doppler" kind of thing, Ithink I understand, as a passenger on this craft,the stars around would redshift down into the infra red, so would the light bouncing off the objects in the craft, including yourself, eventually, as you approached the speed of light,you would become dimmer .

BUT according to other threads here,the speed ofl light is unaffected by even approaching tha velocity.

am I a retard? cant figure this

youre getting at a "doppler" kind of thing, Ithink I understand, as a passenger on this craft,the stars around would redshift down into the infra red, so would the light bouncing off the objects in the craft, including yourself, eventually, as you approached the speed of light,you would become dimmer .
At very high speeds, the stars in front of you would be Doppler shifted to blue, the ones behind you to red, and the ones to your side to varying degrees in a continuum. Presumably the light shining on you personally is generated by sources inside the ship and so is not Doppler shifted at all.

Electromagnetic radiation, such as visible light, travels at the speed of light, at least in a vacuum, and matter cannot reach the speed of light, because it would take infinite energy.

Dwayne: No. The light would still reach you, it would just be lower in energy because of red shifting.

A particle's wave momentum is scaled by Planck's constant to a base order of 10^-34. You'd need a pretty intense source to produce any non-negligible thrust.

Well I mean that the light from a give planet, or atom would never reach you, the only light that could be seen would be risual light that you where travling towards possibly.
light traveling torwards your envolope would be reflected, so it would never enter your envolope to see.

planets and say atompshere would become one blur like a rainbow or white light as we increased up to light speed, Around light speed atmosphere and planets would seem to shrink, becoming speckles, or like the stars when we see them on a dark night. If you where in a atomsphere it would look like sparkels or slit in clear water, like the stars, as you past the speed of light it would become invisable. Fixed figures would become invisable as the light would never reach you.

The simularity of this aspect of becoming like sparkes or invisablity of fixed objects, is very simular to the view that we have of space from earth, being suggestive that either space or earth is actually traveling faster than light speed or around light speed.

Dwayne D.L.Rabon
Why would light be less likely to reach you than if you were at home in a chair? I don't see your reasoning at all. Observers in the moving craft, measure light from any source to be propagating at c, regardless of the source's state of motion compared to them. This is one of the two postulate from which relativity was derived.

How is something "suggestive" that anything is travelling faster than the speed of light? Light travels at light speed, and matter cannot be accelerated up to light speed.

Please cite your sources for your assertions.

Sorry for not replying sooner, it's just that Australia was cut off from the rest of the net yesterday. Today I am unavailable.

You have some interesting inforation and theories, I will read them when I return!

Regrads,
J.

Sorry for not replying sooner, it's just that Australia was cut off from the rest of the net yesterday.

:bugeye:

You must live in another Australia?

:bugeye:

You must live in another Australia?

No, I think that Queensland remained up for most of the time!

The rest of the country was out for quite a while!

You might be wit telstras extra, not who we go thru! (And most of Australia too.) :p

Regards,
J.

locked

a ship tha t was already under acceleration, from breaking gravity would already have some inertia, and would only require a moderate photon force acting apon a light sail to continue the acceleration,and the acceleration would be cumulative in the vaccum of space.......

Light that you are traveling way from can never reach you as you are traveling faster than light speed, you are traveling faster than light propagates.... As you the traveler broke the light speed barrier the stationary sparks of fixed light would become smaller, which would add addtional viablity between the density of sparks. At a further increase in speed the fixed and decreaseing sparks (both in size and number) of light would disappear.
You appear to have never seen a book on special relativity. If you left the Earth travelling at 99% the speed of light, and someone on the Earth aimed a flashlight at you, you would see the light from the Earth approach you at 100% the speed of light, not 1%. All observers will measure light as propagating at the speed of light, regardless of their relative motion to the source. You need to use the relativistic, not the classical, velocity addition formulas.

All of your comments concerning what an observer travelling at or faster than the speed of light would see are incorrect, since nothing composed of matter can accelerate to the speed of light.

Cite your sources for these claims.

Well, you could find this in any number of books about special relativity, but I'll summarize. In order for an object to reach the speed of light, it has to be accelerated to that speed. As the speed of the object increases, its mass increases, so that each additional mile per hour of speed requires more energy than the previous mile per hour of speed. To actually accelerate an object - even one atom or electron - to the speed of light would require an infinite amount of energy.

It makes no sense to make assertions about areas of Physics that you are not familiar with, any more than it would make sense to critique techniques of brain surgery without studying biology or medicine.

The total energy of a massive particle is m0c^2/sqrt(1-v^2/c^2)

Subtract the rest energy, m0c^2, and the rest is the kinetic energy in free space.

I really do not want to argue with you brandon, but it appears that you lack the ablity to define your sceintific facts, and obseravtion, appeartnly you have assume to many assumptions, and think that a atom can not travel the speed of light.

I agree with you that to make assertions about areas of physics that you are not familuar with makes no sense.

so you brandon9000 make some sense, lets see your math.
Dwayne D.L.Rabon
In 1905, Einstein showed that no material object may be accelerated to the speed of light, and this has been accepted by essentially all physicists on Earth for about a century. You can find the math in college textbooks all over the world, but I will refer you to Einstein's paper:

http://www.iitk.ac.in/phy/phy102N/Einsteins_paper_relativity.pdf

Well Brandon9000 to agree that atoms emit light.


If so then what is the energy and speed of that force nessacay to produce light.


DwayneD.L.Rabon
Many people, when losing an argument, will respond by attempting to change the subject, or introduce additional subjects. I won't allow you to change the subject until the first point is resolved. I said that no material object can accelerate to the speed of light, because it has been accepted by the world scientific community for a century. You are clearly discussing a topic of which you have no comprehension.

Unfortunatly many people assume to much when in a argument.
The event of asking if you had come to the affirmation that atoms emit light to simply to gain a understanding that light is emitted from a atom.

in this case which has appreantly become a argument, you stated that a atom which is know to consist of matter can not travel the speed of light. this same atom is known to emit a various spectrum of light, here simple deduction determines that light is closly associated with the atom as the atom is the production of light.

I be short with you brandon9000, in order for light to exist as a body,particle, photon how ever you wish to term, it must have a rate of induction for it to travel, and for it to form. what ever rate of induction that we choose to assign to light, it is greater than the speed of light, therfore if light is measured with a speed of 186,000 mph the event of force inducting light is greater than the speed of light.

so i will ask you again does a atom emit light, and what is the nessacry energy and speed of that energy to produce light.
1. Atoms can emit photons. The photons emitted travel at the speed of light. The atom, however, cannot be accelerated to this speed. If one attempted to do so, the equations of special relativity show that the energy required would be infinite.
2. The process by which the photon is created is unknown.
3. You have failed to define what you mean by induction. Please do so. I refuse to argue with someone who will not define his terms. Also, explain what you mean when you say that the rate of induction of light is greater than the speed of light.
4. Which energy are you referring to exactly in your last sentence, when you refer to the energy producing the light, and what do you mean when you refer to this energy's speed?
5. It appears to me that you have no familiarity with this topic. Do you, and if so, what is your background? Why do you believe that you are qualified to argue the fine points of quantum electrodynamics with no knowledge of the subject? While any argument can be discussed based on its merits and not its origin, it is simply foolish for someone with no knowledge of physics to dispute accepted theory. Theories in physics are not often disproved by people who have not taken the trouble to learn them.

Enough, Atoms emit light, so then either atoms travel faster than light, or light is inducted/attracted from a atom faster then light....
The fact that atoms emit light, does not in any way imply that atoms can be accelerated to the speed of light. Atoms in materials which are not even in motion at all emit light. You appear to be implying that at some point in the process of the creation of the photon the atom is emitting, there is some material object travelling faster than light, but you only hint at this vaguely, with no explanation. Explain.


Dont get of subject Brandon9000 induction is induction and the word induction is defined in the dictionary.
HA,HA,HA
Words defined in dictionaries rarely have much resemblance to the way the words are used in science, unless the dictionary chooses to include a scientific definition. My Merriam Webster dictionary defines the word induction as follows:

n 1: the act or process of inducting; also: initiation 2: the formality by which a civilian is inducted into military service 3: inferences of a generalized conclusion from particular instances; also: a conclusion so reached 4: the act of causing or bringing about 5: the process by which an electric current, an electric charge, or magnetism is produced in a body by the proximity of an electric or magnetic field.
Which of these definitions corresponds to the way you are using the word? None seems to fit. Are you afraid to define your terms? That's hardly a characteristic of someone who is right.


in order for a object to travel to another point it must have a rate of force and a rate of induction. if a object has no induction it must exspend energy to exchange energy with the direction it wants to travel
What do you mean by "rate of force?" What do you mean by "rate of induction" (assuming that at some point you define induction)? What do you mean by an object exchanging energy with a direction?

Furthermore, at any given speed, the kinetic energy of an object is given by the formula:

E = mc^2[1/(1-v^2/c^2) - 1]

where m is the rest mass. As you can see, as the speed approaches that of light, the kinetic energy of the object approaches infinity. Where do you propose to get an infinite amount of energy?

If you are correct in your belief that material objects can be accelerated to or beyond the speed of light, it would be a huge revision of a century old accepted theory. It would be news worldwide. Do you plan to publish your work in any actual scientific journal? May I suggest "Physical Review?"

Despite your colorful debating technique, it is clear that you have no credentials of any kind in this subject. If I am wrong, merely tell me what your credentials are. This is not art criticism. You actually have to know something about this subject to discuss it meaningfully.

Brandon9000: Welcome to scifourms.

Don't bother trying to argue with DwayneD.L.Rabon. He's a total crackpot who has lurked around here for some time. In arguing with him you are making the mistake of assuming that if you present your (correct) arguments in a clear and logically sound manner that he will be convinced. This is futile, because like most crackpots his 'understanding' of physics is so radically different from the mainstream that he doesn't even use basic terms in the same way. It's nice of you to try to educated him, but he isn't really interested in being educated; he will simply ignore anything that you tell him if it doesn't fit with his bizarre views. Trust me, you won't get anywhere. Trying to argue with him only encourages him and pollutes threads with off-topic discussion.

Thanks for the welcome and the 411 Nasor. I have followed your posts in this and other forums at this site with interest since I arrived here. I look forward to speaking to you in the future.

Don't bother trying to argue with DwayneD.L.Rabon. He's a total crackpot who has lurked around here for some time. In arguing with him you are making the mistake of assuming that if you present your (correct) arguments in a clear and logically sound manner that he will be convinced.

Oh no, not another one...

3. You have failed to define what you mean by induction. Please do so. I refuse to argue with someone who will not define his terms. Also, explain what you mean when you say that the rate of induction of light is greater than the speed of light.


At least you have a hint for the answer in your question. Since the rate of induction must be greater than the speed of light, they must have the same dimension in order to compare them. Since the speed of light has dimension [length]/[time] and the rate of induction has dimension:/[time], obviously the dimension of Induction is length.

What is this length?
Well in the same way that mass (in nonrelativistic physics) is defined in Newton's second law of motion, the induction is defined in "DwayneD.L.Rabon" laws of motion:
in order for a object to travel to another point it must have a rate of force and a rate of induction
I have allways thought that for an object to travel from one point to another it must have a velocity.
Silly me!!!!
How couldn't I notice that it must have a rate of force and a rate of induction?
I must be realy stupid.

Since I am so stupid, please, DwayneD.L.Rabon, can you explain me from Maxwell's equations ∂_μF^μν = 4πj^ν and ∂_μF^*μν = 0, how do you get that the source of the em waves (the photons) must move with the speed of light ([I]i.e. j^μj_μ = 0)?

Oh no, not another one...
Once you get used to the old ones, then new ones appear.
Question:
Is this a spontaneous emission of crackpots or a stimulated emmision of crackpots.
In my believe it is both.
Now, if we put them all together in a resonant cavity, by using population inversion with both the stimulated emiision of crackpot, I am sure that we could make a very powerful weapon that I call BASEC (BS Amplification by Stimulated Emission of Crackpot), or even better: BASIC (BS Amplification by Stimuated Induction of Crackpots).
I really like the word "induction"

…
If you left the Earth travelling at 99% the speed of light, and someone on the Earth aimed a flashlight at you, you would see the light from the Earth approach you at 100% the speed of light, not 1%. All observers will measure light as propagating at the speed of light
…

So a rocket travels at 99% speed of light and light is send towards it after 99 years then will it reach the rocket within one years ? that’s because for the rocket light will travel at light speed and not at 1% speed of light.

All of your numbers are wrong, but my point was that if any observer measures something, such as a light beam, as travelling at the speed of light, then all observers will measure that things as travelling at the speed of light, no matter what their relative motion.

Earth bound observers sending out the light beam will see it propagating towards the space ship at 100% the speed of light, and people in the space ship will see it approaching them at the speed of light, no matter what the velocity of the space ship relative to the Earth.

Once you get used to the old ones, then new ones appear.

Very sad indeed. Oh well, it just takes away the fun of posting on this particular forum, which is something I think is true for many of the more educated people who keep this forum running (on the level of physics)

…
Earth bound observers sending out the light beam will see it propagating towards the space ship at 100% the speed of light, and people in the space ship will see it approaching them at the speed of light, no matter what the velocity of the space ship relative to the Earth.

So U r saying that a ship traveling with the light at 99% speed of L will also seem to reach early for the first ship ? I mean why only light, whats so special about it ?

So U r saying that a ship traveling with the light at 99% speed of L will also seem to reach early for the first ship ? I mean why only light, whats so special about it ?
There is nothing special with the speed of light.
The nature of space-time is such that there is a speed which is invariant under all reference frames. That is, the nature of space time is such that intervals are invariant under Lorentz transformations. All massless particles travel at this speed. Light being massless will also travel at this speed. Light is an electromagnetic phenomenon. Since the everyday life is governed by electromagnetism, light was the first thing that was discovered to travel at this invariant speed (from this the name of speed of light). Gravity is not strong enough to be felt (except for very large bodies such as the earth). The strong nuclear force is much stronger than the em force however it is of very short range and this is the reason why we don't feel it in the everyday life, however the mediators of this force are massless and travel also at the speed of light.

So U r saying that a ship traveling with the light at 99% speed of L will also seem to reach early for the first ship ? I mean why only light, whats so special about it ?
As the previous poster pointed out, it has been known since Einstein's first relativity paper in 1905 that if any unaccelerated observer measures the speed of something as being C, then all unaccelerated observers will measure the speed of that thing as being C. This is true even if the two observers are in motion relative to each other. C is a special speed that has this property. Light is an example of something that propagates at this speed. This has been verified experimentally countless times over the past century and is one of the two postulates from which relativity was derived.

It seems that the topic is "light drive".... now this has been discussed as travelling at the speed of light, then there was the endless debate and banter whilst some of us came to grips with relativity.... If I read one more post that starts with......" so theres this guy , right...and he's on a rocket going away from earth at the speed of light...."
I'm going to stick thumbtacks in the roof of my mouth.

The speed of light is the general road rules for the universe as we know it so far,
for mass to be accelerated to that speed would require infinite energy.Look at what happens at the event horizon of a black hole, any mass unfortunate enough to be caught in the gravitational field is accelerated,not only in distance but slowed down proportionately in time as well.
In the brief instant before an unlucky astronaught fell beyond the horizon, he would witness the fate of the universe in fast forward, just before he was stretched ad infinitum.

There have been some theories, proposing the use of space itself to reduce the profile of the mass of the craft itself, a la "Dr Whos Tardis" whereby a microscopic object can travel vast distances unhindered by its mass, but on the inside can be large enough to hold occupants.

Does anyone else think that the key lies not with light , but with space/time and gravity?





p.s Rabon, PLEASE USE SPELLCHECK OR SOMETHING, YOU LOOK RETARDED FROM HERE

... even if the two observers are in motion relative to each other. C is a special speed that has this property. Light is an example of something that propagates at this speed. This has been verified experimentally countless times over the past century and is one of the two postulates from which relativity was derived.

That just shows how wrong everthing has been concluded. My question is why only light. And why is this C the end of imagination for 99.99% humans. to me That sounds like alien brain wash conspiracy against humans.

Actually both sides here are taking a bit of liberty with truth.

1 - There has certainly been no proof given here that light has mass.

2 - It is equally wrong that some here have claimed it has been proven that light is massless.

The actual status is that if light does have mass then all current theories are invalid. That is not "Proof" in the correct sense of the word but it certainly gives it considerable weight as being fact.

Actual testing has proven that the mass of light is something less than 1E-66kg.

You can't ever really prove that light has no mass, just like you can't ever really prove anything. No matter how many experiments you come up with to show that light has no mass, I can always just claim that your experiments are flawed, that you faked the data, or some other thing.

When dealing with the real world it is only ever possible to weigh evidence and make informed decisions based on what you know. There is a vast body of evidence to indicate that light does not have mass, and no evidence that it does. So unless you're some sort of hyper-skeptical person who doubts everything and believes in nothing, the only reasonable conclusion is that light has no mass. It's especially sad that most people who cling desperately to the idea of light having mass seem to do so simply because they don't like it that light doesn't have mass. It's obvious that rather then trying to come to a conclusion by examining evidence, they're simply deciding that light must have mass because it hurts their brain to believe otherwise, and so they ignore the evidence and try desperately to come up with a reason why light must have mass.

If you don't want to believe that light is massless then that's your right, but be aware that every serious physicist in the world disagrees with you. Yes, it's possible that you're right and ever physicist in the world is wrong, but I would suggest that you carefully examine how unlikely that would be.

2 - It is equally wrong that some here have claimed it has been proven that light is massless.



MacM, I once showed you how from the principle of gauge invariance you must have an electromagnetic field which has the Maxwell's equations as fields equations. You must surely know that from Maxwell's equation, light is massless.(http://www.sciforums.com/showthread.php?p=463762#post463658)

I'll repeat you the proof here:


Suppose you have some scalar complex field Ψ(x), whose equation of motion are deduced from a Langrange function.
Since the relevant physical parameter is |Ψ(x)|²,
if you do the transformation
Ψ(x) --> exp(i α )Ψ(x),
your equation of motion will not change.
But what happens if someone makes a phase transformation and somebody else makes, somewhere else, another phase transformation. Since , as said earlier, it is |Ψ(x)|² which is important, that should be OK. So the field equation should still be the same under the transformation
Ψ(x) --> exp(iα (x))Ψ(x) (This is called a gauge transformation of the first kind)
Now if you look at the Lagrange function for Ψ, it contains derivatives of Ψ, so that under the gauge transformations' we get
∂_μΨ --> exp(iα )∂_μΨ + i(∂_μexp(iα ))Ψ

However if there exist some compensating field A_μ such that in the Lagrange function, ∂_μ is replaced by
∂_μ + iA_μ, such that this field changes to:
A_μ --> A_μ + ∂_μα (this is called a gauge transformation of the second kind)
Then the field equations remain the same.

Notice that since i∂_μ is the 4-momentum operator, what we got is that P_μ is replaced by P_μ - A_μ. This the classical result of classical mechanics in the presence of an EM field.
So that A_μ is the EM field (or more precisely the vector potential).

If we look at the fields equation for A_μ, it can be shown that the simplest equation available and that are compatible with SR are:
∂_μF^μν = j^ν.

Where F^μν is defined as F^μν = ∂^μA^ν - ∂^νA^μ

And

j^μ = i(Ψ*(∂^μΨ ) - (∂^μ(Ψ *)Ψ ).
Since ∂_μj^μ=0, it is a conserved current, and the fields equation are the Maxwells equations.

Conclusions:

Under the assumption of a relativistic field theory, in order to have a local phase invariance, there must exist a compensating field whose field equations are the Maxwell's equations.
This is the EM field.

That just shows how wrong everthing has been concluded. My question is why only light. And why is this C the end of imagination for 99.99% humans. to me That sounds like alien brain wash conspiracy against humans.
It is not only light. It is a special property of this speed, and light is the most noticeable thing that travels at that speed.

What it is is a theory based on sound theoretical work, and a century of experiment. There have been a lot of very clever and skeptical physicists since 1905, and if the work did not appear to be correct in some obvious way, many would have said so. Instead, it is the judgement of a century of phsycists that Special Relativity seems to be right.

I suggest that if you are firmly convinced that you are correct, you submit a paper to an actual physics journal. It would be the discovery of the century.

That just shows how wrong everthing has been concluded.

What shows how wrong everything has been concluded?


My question is why only light.
It's not only light but everything massless that travels at c.


And why is this C the end of imagination for 99.99% humans.

If you would have known physics, you would have known that it is the starting, not the end.
You must indeed belong to the 99.99% who do not know physics and think that this is the end of imagination.


to me That sounds like alien brain wash conspiracy against humans.
To me, this sound like a poor excuse for not understanding SR.

Nasor and
MacM, I once showed you how from the principle of gauge invariance you must have an electromagnetic field which has the Maxwell's equations as fields equations. You must surely know that from Maxwell's equation, light is massless.(http://www.sciforums.com/showthread.php?p=463762#post463658)

I'll repeat you the proof here:

I didn't claim otherwise. Infact I stated that the bases for claiming no mass are current theory. You have not jproven light has no mass you have jproven only that Maxwell requires it have no mass.

I really care less if it has mass or not. My point was the miss statements being made.

I didn't claim otherwise. Infact I stated that the bases for claiming no mass are current theory. You have not jproven light has no mass you have jproven only that Maxwell requires it have no mass.
No, what I have proven is that by the gauge principle, you must have a massless field that solve the Maxwell's equations. I suggest that you read the proof again and if you don't agree with the proof, show me where it is wrong.


I really care less if it has mass or not. My point was the miss statements being made.

If you don't care, then don't say:
2 - It is equally wrong that some here have claimed it has been proven that light is massless.
However, if you say that, be ready to be shown that you are wrong by claiming this.

No, what I have proven is that by the gauge principle, you must have a massless field that solve the Maxwell's equations. I suggest that you read the proof again and if you don't agree with the proof, show me where it is wrong.



If you don't care, then don't say:
.
However, if you say that, be ready to be shown that you are wrong by claiming this.

I do believe the following from your posts says it all. A conclusion beginning with an "Assumption" is exactly as I have stated. You have only proven that in accordance with preferred current theory that light is massless.

Conclusions:

Under the assumption of a relativistic field theory, in order to have a local phase invariance, there must exist a compensating field whose field equations are the Maxwell's equations.

This is the EM field.

I do believe the following from your posts says it all. A conclusion beginning with an "Assumption" is exactly as I have stated. You have only proven that in accordance with preferred current theory that light is massless.
When you talk about photons, you talk about quantum field theory. When you ask about the mass of a photon, you make some assumptions. Under the same assumptions I have shown that there must be an em field, and that the photon (which is this field) is massless.

When you talk about photons, you talk about quantum field theory. When you ask about the mass of a photon, you make some assumptions. Under the same assumptions I have shown that there must be an em field, and that the photon (which is this field) is massless.

So then we are in agreement. The massless photon is based upon assumptions from current theory and is not proven in any physical tested way. That testing shows only that the mass must be under approximately 1E-66kg or 1E-60 kg I forget which right now.

upper limit for the mass of a photon 3.0 x 10/-53g

If a photon is to intreact with any body it must have a mass, a body that provides it wave form. to say that a photon has no mass is pure non sense.

DwayneD.L.Rabon
Have you ever taken a class in quantum mechanics?

So then we are in agreement. The massless photon is based upon assumptions from current theory and is not proven in any physical tested way. That testing shows only that the mass must be under approximately 1E-66kg or 1E-60 kg I forget which right now.

Note that all tests also rely on theory. The tests you accept rely directly on what theory you accept.

Note that all tests also rely on theory. The tests you accept rely directly on what theory you accept.


We are very much in agreement. But what I see is that much if not most or all, test data doesn't exclusively support Relativity. That is it only doesn't exclude it but could just as well fit alternative descriptions of reality but it is repeatedly referred to as the bulk of proof of Relativity without giving any consideration to the fact that it isn't exclusive at all.

Well Brandon you are not quite making sense, as the feild travels considerablly slower than the photon.


Dwayne D.L.Rabon
What are you talking about? You making assertions related to quantum electrodynamics, so I asked you if you'd ever taken a quantum mechanics course.

locked

Your making comments that assume that the universe does not exist.


So now your are going to tell me that a secondary feild travels the same veloicty as the photon it self. but wait you said that the feild generated the motion of the void called a photon.

MASS, the measure of the inertia of a body, as indicated by the acceleration imparted to it when acted upon by a given force and which may be exspressed as the quotient of the weight of the body divided by the acceleration due to gravity.

Light does have a sine wave, and is produced by various degrees of eletric pressure.



I noticed that you keep making reffernce to my creditails, but you can not affirm you concepts regarding a photon, HA,HA,HA


Dwayne D.L.Rabon
I can't recall assuming that the universe doesn't exist, and, in fact, I have reason to believe that it does since I am sitting in it right now.

Your formula relating force, mass, and acceleration applies only to the special case of falling objects. In Newtonian physics, the mass of a body which is acted upon by a force can be calculated as the force divided by the acceleration imparted by that force. Regarding the formula you lifted with no comprehension from some physics book - the weight of the body divided by the acceleration due to gravity gives the mass of a falling object. The issue is irrelevant, though, since Newtonian formulas don't apply.

The prospect of responding to your posts is not very tempting, since they contain implicit misonceptions, undefined terms, and are clearly the work of someone with no familiarity with the topic. I would be more inclined to respond to an assertion I disagree with if it at least indicated familiarity with the subject matter, and was clearly formulated. From this, and from your refusal to discuss your credentials, I can conclude that you have never been exposed to the theories you are attacking. When accepted theories in physics are revised, it is never by people who are unfamiliar with them.

upper limit for the mass of a photon 3.0 x 10/-53g

If a photon is to intreact with any body it must have a mass, a body that provides it wave form. to say that a photon has no mass is pure non sense.

DwayneD.L.Rabon
Do you know what is mass?

To me, this sound like a poor excuse for not understanding SR.

Do U really believe I would jump in a waterless well after looking at Ur brain hamerage.

I would rather waste all my life digging a new freash water well, With or without humans, All by myself and may be MacM.

locked

What i am saying is that you do not know what you are talking about.

There was a fellow here with a similar name "Dwayne D.L. Rabon" who was a genuis with science and could talk circles around the best of them. Maybe some day he'll come back. What a guy!

all confrim that light has mass.

If he does come back, you should definitely get into a discussion with him - he showed us all that light has NO mass. We simply could not refute his arguments. What a guy!

:D

What i am saying is that you do not know what you are talking about.:eek:

There was a fellow here with a similar name "Dwayne D.L. Rabon" who was a genuis with science and could talk circles around the best of them. Maybe some day he'll come back. What a guy!

all confrim that light has mass.:bugeye:

If he does come back, you should definitely get into a discussion with him - he showed us all that light has NO mass. We simply could not refute his arguments. What a guy!


Thanks!:D I surely will discuss it with him. I still say light has mass

Regards,
J.

Thanks!:D I surely will discuss it with him. I still say light has mass


I dont think light has mass because I know light has mass. I aint gonna do any explaining on this, as all of that is done in the recent history at SCIForums threads.

I still say light has mass...

That's fine. But keep in mind that your claim should have some sort of evidence to back it up. I say, "Invisible pink unicorns exist." Do you believe me?

I dont think light has mass because I know light has mass. I aint gonna do any explaining on this

First, you have to understand English before trying to explain anything. Once you've covered that ground, some might then begin to take you seriously.

I still say light has mass...

That's fine. But keep in mind that your claim should have some sort of evidence to back it up. I say, "Invisible pink unicorns exist." Do you believe me?

I dont think light has mass because I know light has mass. I aint gonna do any explaining on this

First, you have to understand English before trying to explain anything. Once you've covered that ground, some might then begin to take you seriously.

Yes, it is fine. I do have evidence! Physics has the evidence I need. Simple physics in fact! Invisible pink unicorns do exist! I haven't seen any, but I've seen quite a few people talking about them! So they must be... right????


Hey, (Q)!!
If you can't interperet all forms of English, then how can you speak to your friends? I can understand him perfectly. I speek mny vrsn o Eng. Vry hlpfl 2 kno wat u tlkng about. That's just sort English! I can do better, but that's for you.

Regards,
J.

Physics has the evidence I need

Sorry, but physics also disagrees with you.

Physics does not. I will get the reference and edit this post to add it!

But now, I have to go to TAFE.

I don't want a reference, I want you to show me the math.

I don't want a reference, I want you to show me the math.
Okay, you willl have the reference, AND the math!

Promises, promises turn to dust... Trust into mistrust.

--- Beautiful South, A Little Time

Promises, promises turn to dust... Trust into mistrust.

--- Beautiful South, A Little Time

Well, Sorry for not replying very soon, but I was called away to work not long after I had posted!

I have figured out the formulae. mind you, it only took me about 2 seconds!

v=ma. no mass, no velocity!

Regards,
J.

v=ma???

*looks through high school physics notes*

What are you talking about?

I think you tried to combine
F=ma
with
v=at

But classical physics doesn't even apply.

v=ma???

*looks through high school physics notes*

What are you talking about?

I think you tried to combine
F=ma
with
v=at

But classical physics doesn't even apply.

Umm, that's possible! I may have, but that's what I remember.... I'll look it up again!..................................

Well, I'm probably wrong, so, Ill try to calculate the formulae that I used to use in high school. I don't have my notes any more, ever since our house caught fire, I have lost many a physic notes.

Anyhow, Thanks! I will try again!

Thanks for the inspiration aswell!

Regards,
J.

I don't have my notes any more, ever since our house caught fire, I have lost many a physic notes.

:rolleyes:

v=ma

v=velocity
m=mass
a=acceleration

Is this correct?

I don't have my notes any more, ever since our house caught fire, I have lost many a physic notes.

:rolleyes:

v=ma

v=velocity
m=mass
a=acceleration

Is this correct?
Yes.

Mass times acceleration equals force, not velocity. Acceleration is a change in velocity, so changing the size of the mass will not change the velocity.

Q is right, "v=ma" is not a correct formula. It should be f=ma, or v=ta.

Mass times acceleration equals force, not velocity. Acceleration is a change in velocity, so changing the size of the mass will not change the velocity.

I understand. I must have been confused somehow. I was working on several things at once, I may just have remembered it wrong because Iwas using many a formulae.

Thanks. To both of you.

Regards,
J.

Q is right, "v=ma" is not a correct formula. It should be f=ma, or v=ta.

Hey guys! Why does Q get credit for repeating what I said?

Because he said it last ;)

Since when was it proven that light is made of strictly photons and since when did they have a registerable mass (that is if their mass even exists). Who answered the "Light: particle or wave" question?

Hey guys! Why does Q get credit for repeating what I said?

He get's credit because he was understood. Or, I may not have read your post because others had arrived, or you posted when I was not online for a week or so!

Well, thanks anyway.

Regards,
J.

(Sigh.) Protagorus, light is both a particle and a wave.

Actually, it appears to be neither (but has properties of both).

Protagorus

You might want to start with Maxwells equations.

Protagorus

You might want to start with Maxwells equations.

What's with all this 'Protagorus' stuff???

One critical trait of a good scientist is "attention to detail"...

Protagoras was a Greek philosopher.

Allow me once again, the event that light is polarized, exsperinces cross anhilation, and can be divided in to other light waves, and the event that it has a sinal wave, all confrim that light has mass.
You're barely speaking English, but I'll try to respond. First of all, the term cross anihilation has no meaning that I know of in science, but perhaps you mean destructive interference. Both the existence of destructive interference and the sinusoidal nature of the fields prove only the wave nature of light, not that it has mass.


You asked me for my creditals as if it was to give some defense...
You have no experience with nor knowledge of Physics and, additionally, lack the integrity to simply admit it.


...i guarntee, that you will lose in a argument with me, in verbatium, or numerical exspressions. I will tell you ahead of time i will make you eat it.
Off topic, childish, and irrelevant.

The simple comments are just simple points of conversation, it is you who have failed to apply to common sense relavant to you concept of numerical deductions appreantly as you have stated that light/photon had no mass. This leads me to think that you are refereing to AMU, but say that you have a better comphresion than me. As well you said the atom did not travel the speed of light.(lest not forget that brilliant assertion of yours HA,HA,HA!!!!!!)
What?

So then lets begin the argument on your turf smarty!!!!HA,HA,HA how is it that we should define mass according to your numerical vaules.
Mass is defined in every high school Physics book in the world, so why should I cut and paste in a definition anyone could find in ten seconds? If you don't know what mass is, then you certainly shouldn't be declaring accepted science to be false. Theories in Physics are never revised by people who know nothing about them.

Now, one subject I know nothing at all about is medicine. Yet there is nothing to actually stop me from posting gibberish on medical sites and telling the doctors that they're ignorant fools, but we all know how much value that would have.

Brandon

You have no experience with nor knowledge of Physics and, additionally, lack the integrity to simply admit it.

Welcome. I see you've met one of our 'gimcracks' and have come to the same conclusions.

Have fun.

Brandon

You have no experience with nor knowledge of Physics and, additionally, lack the integrity to simply admit it.

Welcome. I see you've met one of our 'gimcracks' and have come to the same conclusions.

Have fun.
Thanks.