Mass of light.

G

GRO$$

Registered Senior Member
I was thinking about this...

An object accelerating towards c (speed of light) gains mass as it nears c... how i see it is c being an asymptote of a graph, the closer the object gets to c, the closer its mass is to infinity...

Now, if light has a mass, because it cant escape black holes and is bent by stars and other heavy things... if it moves at the speed of light, shouldnt light become very very heavy? Infinately heavy?

Is there something wrong in my reasoning somewhere? Where?

Hm... woa... quick cool theory just popped up in head... maybe c is not limit of travel, but just below the limit... making photons very heavy and visible and stuff only when they at c... when they hit something and are absorbed by it, they slow down, and are all of the sudden so light and with so little mass, that they might as well just dissappear...

/patent
/claim

If this idea wins nobel prize... i posted it here 1st!... unless i saw/heard it somewhere else and subconciously memorized it, just to think that its my original idea now...

Ok, this should have been two posts, but what faults are there in my 2 theories? The light being infinately heavy one and the light being heavy or noticeable as long as it moves at light speed... only to be really massless when it stops.
 
Now, if light has a mass

Light has no mass.

shouldnt light become very very heavy? Infinately heavy?

If light has no mass, it can't get "heavy."

btw - light has no mass.

Is there something wrong in my reasoning somewhere? Where?

Yes. Light has no mass.

maybe c is not limit of travel

c, the speed of light, 299,792,458 meters per second,186287.490 miles per second, is the limit.

Light has no mass. The ultimate speed limit is the speed of light.

:)
 
Are you sure light has no mass? I definately have repeatedly seen otherwise.. :)
 
Are you sure light has no mass?

Pretty sure.

I definately have repeatedly seen otherwise

Don't believe it.

;)
 
Hi GRO$$,

"An object accelerating towards c (speed of light) gains mass as it nears c... how i see it is c being an asymptote of a graph, the closer the object gets to c, the closer its mass is to infinity... "

Objects don't get "heavier" when they move faster. They only get more energy. In relativistic mechanics, the concept mass is redefinied to include the energy. Hence, since the energy increases, the mass increases (with the sidenote that you should know what is understood by "mass" in relativistic theories).

Bye!

Crisp
 
Response to Q's response

"Q"

You have ridiculed my last two theories and now my friends theory. Light does indeed have a mass!! If light had no mass like you are saying then why does it curve when it passes by stars, and black hole??? ever think of that??? A Photon is what makes light have mass, just incase you didn't know Photons make up light!! They are what we call "sub-atomic" particles, I would suggest to you that you start reading some physics books, and maybe, just maybe you might be right about something down the line.


BTW: Nice theory Andrey, lol
 
thank you. I am also a little frustrated about (Q)'s aggressive approach to other's ideas... why do you think light has no mass tho? I always have assumed it has, I think I learned it somewhere long ago and never really questioned it... it would make sense for it to have mass...
 
Hi GRO$$,

This is one of the reason's why I have always been against not using the word "relativistic" when talking about mass in special relativity.

Light does not have a restmass: m<sub>0</sub> = 0. This means that if you could ever put a photon on a balance, it would read 0.00 grams.

Light does have relativistic mass (which is commonly called just "mass" in the theory of relativity, but which does NOT refer to the restmass). The (relativistic) mass of a photon is related to the momentum/wavelength/frequency of the light.

Light does not bend near the sun because it has "mass" (in all possible meanings of the word). The theory of general relativity states that light follow a straight path in spacetime, which is bent near a gigantic object like our sun. A straight path in a bent spacetime is perceived by us as a bent path in our regular universe.

Hope this settles the discussion :).

Bye!

Crisp
 
it settles a lot i think crisp, i remember reading about spacetime cured at gravity, i can look like i understand what its implying, but i havent really gotten my mind around the concept... which way is it curved? into another dimention?
 
so what u are saying Crisp is that Light only has a mass when it is relitive to space and time. for example if x=mass of light, and space =n, time =y :


x=0



===but===


(x)(n)(y)= unknown mass?



When I say unkown mass I mean any type of mass but it is unknown to us because it is only in theory.

Am I right, if not please explain to me, thanks a lot crisp for clearing it up.
 
what hes saying is light has no mass, and travels in straight line always... but gravity bends space-time, so it travels in straight line thru curved space-time...

correct me if im wrong please...
 
Hi all,

GRO$$,

"which way is it curved? into another dimention?"

Okay, I'm going into a domain that I never studied extensively, but I'll give it a shot anyway.

It's not curved into another dimension, it are the dimensions themselves that are curved. The best way to visualize this is probably with the following analogy. Suppose that we were confined to a 2D spherical surface. This means that there would not exist any up or down, just forward/backward and left/right. If you start walking somewhere on the sphere and keep on walking forward, then you will say that you always follow a straight path (assume that the sphere is very huge and that you don't walk all the way around it). For someone who lives in a three dimensional world and can observe the sphere, you would have walked a curved path. For someone living on the sphere, it appears that their living world is the same in all directions (flat, you are confined to the sphere) but someone who lives a dimension higher clearly sees that your living world is curved. Replace the 2D world by our 4D spacetime and you more or less get the real situation. However, there's no extra fifth dimension (yet :)) where you can observe our curved 4D spacetime.

The analogy doesn't quite work because it is somewhat the other way around: it is the 4-dimensional spacetime that is curved, and what we perceive as 3D straight paths are really curved paths in 4D spacetime, and the other way around (straight path in 4D, eg the path of light, is curved in 3D -> which is why light bends).

S. Dalal,

"so what u are saying Crisp is that Light only has a mass when it is relitive to space and time".

Eeeeehrrrr.. no. If you want to talk about light in a proper theoretical way, you have to talk about a theory that happens to be called "the special theory of relativity". The reason why it has the word "relative" and "special" in it is a long and boring story (I'll just skip that for now :)). It has nothing to do with being "relative to space and time".

Bye!

Crisp
 
You have ridiculed my last two theories and now my friends theory.

Don't know who your friend is but your theories are nonsense.

Light does indeed have a mass!!

Light has no mass. Get over it.

If light had no mass like you are saying then why does it curve when it passes by stars, and black hole??? ever think of that???

Geodesics (straight lines) curve near matter because the geometry of spacetime is curved (gravity). Light follows a straight line (geodesics). Hence if the geodesics are curved and light travels along the geodesics, light appears to curve around matter (stars, black holes, etc.). Is that clear enough?

A Photon is what makes light have mass

Really? I thought photons were tiny energy packets of electromagnetic radiation.

They are what we call "sub-atomic" particles

Photons are bosons. Bosons have no electric charge or rest mass. They are field particles that are thought to be the carriers of the electromagnetic field.

I would suggest to you that you start reading some physics books, and maybe, just maybe you might be right about something down the line.

Uh.....yeah, sure. :rolleyes:
 
I am Stephan's friend he was reffering to, I know him in real life :)

"Photons are bosons. Bosons have no electric charge or rest mass. They are field particles that are thought to be the carriers of the electromagnetic field."

hm... if they have no rest mass, how do they exist?

i am finding it hard to understand how something has no mass ... how can it exist?
 
Mass is just one of the properties that a particle can have. It can also have energy, momentum, spin, electric charge and colour charge (related to the strong force). It can have some of those things and not others.

A photon has no rest mass, no charge and no colour charge. It does, however, have spin. It also has momentum and energy.

The concept of relativistic mass causes more confusion than it takes away. Physicists these days have pretty much dispensed with the idea. Instead, they talk only about rest mass.
 
So it has energy without mass? cool... any good sites on the subject u guys can suggest, or should i just look it up on google?
 
Originally posted by S. Dalal
so what u are saying Crisp is that Light only has a mass when it is relitive to space and time. for example if x=mass of light, and space =n, time =y :


x=0



===but===


(x)(n)(y)= unknown mass?
Click to expand...

i just want to know if everyone agrees with this equation
 
Originally posted by James R
Physicists these days have pretty much dispensed with the idea. Instead, they talk only about rest mass.
Click to expand...

Absolutely. Mass is rest mass in most discussions.

Read the ohter thread on light has mass for more details.

Dave "at rest" Barlow

P. S. Damn i'm meant to be in bed.
 
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