I got to thinking today, if light has no rest mass (therefor allowing it to travel at light speed) what happens in the split second after it has struck a reflector of some kind and come to a complete stop while reversing directions? Why doesn't the light simply disappear? I mean, using common sense one would think if an object has zero rest mass, and it came to rest it would cease to exist. Anyway, thanks for your help.

Light does disappear when it stops. It stops when it is absorbed by something. To be reflected, a photon must be absorbed by the reflector, which then emits a new photon in the opposite direction.

hi,
let us say i take a pulse of photons in a big container.and i have supernatural powers to see distinctly these particles,say these are 30 in no.now i deaccelerate these,without hitting or by anything,but with some medium,then hypotheically what would happen if they stop,in the middle of the container.(disregard HOW will i stop them)what would i see?would i see them vanish?

if photons are included in tachyons category then they should never stop.they should continue to move with "c" speed.

It gets absorbed by an electron.

The electron later can emit another photon, the direction of emission being random and only sometimes opposite the direction of the first photon.

Reflection of photons by a lattice of atoms (an aluminized mirror, for instance) is emission of new photons by electrons which have previously absorbed photons.

I would say that Photon's react similar to electrons or Neutrons when they are singled out, they have a period of time that they exist before their energy disperses into nothing by Zero-point energy.

Since a Photon is lights mass, I would guess it's existance at rest would be such a short period that were wouldn't percieve it existing at rest before it disperses to Zero-point.

Originally posted by Stryderunknown
Since a Photon is lights mass, I would guess it's existance at rest would be such a short period that were wouldn't percieve it existing at rest before it disperses to Zero-point.

are you conveying that it does exist at rest,but due to our techno-inability we just cant freeze a shot of it? :(

let us say i take a pulse of photons in a big container.and i have supernatural powers to see distinctly these particles,say these are 30 in no.now i deaccelerate these,without hitting or by anything,but with some medium,then hypotheically what would happen if they stop,in the middle of the container.(disregard HOW will i stop them)what would i see?would i see them vanish?

The problem with this is that <i>how</i> you stop them will be very important to the answer. What medium are you talking about?

In fact, you can't decelerate a photon. You can only absorb it.

Of course, if you have supernatural powers, all bets are off and you can do what you like. Since you're not constrained by the lws of nature, you're free to make up any explanation which makes you happy. It's your fantasy. :)

There is only one way to stop a photon -- electron absorbtion.

The extra-electron 'medium' is irrelevent (unless you're talking statistics: the chance a photon will be absorbed).

;)

Zion wrote:<BR>are you conveying that it does exist at rest,but due to our techno-inability we just cant freeze a shot of it?

I found a post that explains MIT freezing a Photon within an Sodium Atom
http://csep10.phys.utk.edu/newsgroups/daunt152/messages/66.html

It basically means that the energy can be frozen, but only when it's within a Stiffened electromagnetic field.
I've mentioned before my thoughts on Zero-point energy being the universes natural background level of electromagnetics, that's why originally I said it disperses and my mentioning for a photon dispersing too quickly was only if it had been frozen in space (only with the stiffened Zero-point to hold it).

Of course you could say that freezing a photon in a Sodium atom is just only Freezing it's photoelectric effect.

<<...freezing a Photon within an Sodium Atom ...>>

Consider that the photon (apparently frozen in place within the sodium atom) and the sodium atom both where observed in a laboratory attached to rotating Earth, a planet revolving around the sun, a star revolving around the center of the Milkyway galaxy, a galaxy moving around the center of gravity of the Local Group of galaxies, a group of galaxies moving around the center of gravity of the Virgo Group of galaxies, a group of galactic groups moving...

So, was the photon actually at rest or did it just appear to be at rest with respect to the also moving sodium atom, like resident astronauts and cosmonauts seem to appear at rest with respect to the moving International Space Station?

So suppose I had a container containing absolutly nothing inside (aside from the virtual particles and such). If I injected hydrogen ions (H+), which have no electrons, (or even just a mass of neutrons), then "shot" them with photons, what would happen to the photons as they hit the atoms? I'm guessing the don't just disappear into thin air, so are they absorbed by the protons? Or do they simply not interact with the atoms? Thanks again =)

Originally posted by James R


The problem with this is that <i>how</i> you stop them will be very important to the answer. What medium are you talking about?

In fact, you can't decelerate a photon. You can only absorb it.

Of course, if you have supernatural powers, all bets are off and you can do what you like. Since you're not constrained by the lws of nature, you're free to make up any explanation which makes you happy. It's your fantasy. :)
==============================================
the whole point was what would be my observation once i stop it, how is it going to look like at rest.my theory is that photons cant stop or deaccalerate,they continue to go on their speed and they can never stop,just like tachyons,unless they get hit by something or get absorbed etc.otherwise that could lead to violation of energy,since photons cant exist at rest,so they cant come to rest,any corrections,or inputs to my understandings are welcome.

Xelios

As far as I know about taking a preportion of Quanta from an Atom (Electrons, Protons or Neutrons) They have a period of life span before their energy disperses.

(This is similar to how radiation occurs with high electron atoms, but it's the very quanta that disperses energy and since it isn't apart of a orbital structure it doesn't replenish it's energy through kinetic energy or friction)

So for you to shoot one with a photon you would have to be pretty quick.

You might be able to find more relevant information at:

http://www.cern.ch

Since they have been conducting these sorts of experiments and discussing quantum theory for years.

I would say tht light[photons] has mass. It is proved that the light of the stars is curved(contorted)i.e.affected, by suns gravity force.
In time of solar eclipse stars by the sun appear in different place(of course stars don't change their position, so during the eclipse we can see the true location of stars, of course if their light isn't affected by other big mass objects)

When the light of a more distant star passing near a massive object in space appears to curve it is not because the photons of light are responding to the nearby mass as if they themselves have mass. The photons are moving in straight-line paths. It is spacetime through which they are moving that is curved by the massive object nearby.

It is analogous to a spoon in a glass of water. It appears bent but is not physically bent.

The photon is moving straight. The mass is curving spacetime. The curvature of spacetime makes the photon's straight-line behavior appear to the outside observer to be curved as if in response to the mass, but the photon only knows it is moving straight.

More Einstein, less Newton.

As my understanding goes, when two balls are thrown one with a high velocity and other with less,both will have same trajectory in space-time coordinates,c-t coordinates.this means that light has curved path(ALWAYS)in c-t coordinates,space-time coordinates,its just that it is too fast to see.

bye!

How could I forget that!!!!!!!!!!!!!! I read about spacetime curving in "Short History About Time". Thanx for reminding me tht :)

Re. "There is only one way to stop a photon -- electron absorbtion."

1999

"Recently, the Hau group succeeded in reducing the light speed to 17 m/s (the speed of a racing bicycle) by optically inducing a quantum interference in a Bose-Einstein condensate."

<a href=http://www.physics.harvard.edu/fac_staff/hau.html><font color=red>1999 Article</font></a>

2001

"The sample becomes opaque once more, and the light pulse cannot emerge."

<a href=http://www.nature.com/nature/fow/010125.html><font color=red>2001 Article</font></a>

My, doesn't time fly (and not "in a sodium atom")?

Take care.

Xelios:

An H+ ion is a proton. I suspect that an isolated proton would not normally absorb photons, unless they were of very high energy.

zion:

<i>As my understanding goes, when two balls are thrown one with a high velocity and other with less,both will have same trajectory in space-time coordinates,c-t coordinates.this means that light has curved path(ALWAYS)in c-t coordinates,space-time coordinates,its just that it is too fast to see.</i>

IF two balls have different speeds, their spacetime trajectories (called <i>worldlines</i>, by the way) will be different.

What are c-t coordinates? You're graphing what against what? Distance against time, perhaps? In that case, in Euclidean spacetime light will always have a straight line worldline.

Chagur:

The "slow light" experiments involve atoms absorbing and re-emitting photons (i.e. electron absorption). A specially prepared medium was used in those experiments. A recent experiment actually <i>stored</i> a light pulse in a medium for some time, before re-releasing it. The energy and information about the pulse was stored in the quantum ensemble of atoms in that experiment.

Hi all,

I agree with James R here, the only way to actually stop a photon is by absorption, leading to the destruction of the photon.

However, if - very hypothetically speaking, with some magic wink-wank - you could get a photon to stop, you wouldn't see anything. In order for you to see or detect an object, it has to emit ... light or photons. I still have to hear about photons emitting photons in order to be detected.

Bye!

Crisp

Originally posted by James R
[B]zion:

<i>As my understanding goes, when two balls are thrown one with a high velocity and other with less,both will have same trajectory in space-time coordinates,c-t coordinates.this means that light has curved path(ALWAYS)in c-t coordinates,space-time coordinates,its just that it is too fast to see.</i>

IF two balls have different speeds, their spacetime trajectories (called <i>worldlines</i>, by the way) will be different.

What are c-t coordinates? You're graphing what against what? Distance against time, perhaps? In that case, in Euclidean spacetime light will always have a straight line worldline.

Actually i took the whole idea from general theory of relativity.
==============================================
the fight of two balls can be represented in two dimensions,now we can use the third dimension as space time.they both assumedly advance in X-axis.both the balls will have the same curavture in space time.the earth has caused a curved dimple in nearby space-time.each is following a geodesic.neither of them is experiencing the gravititional force,each is doing what comes naturally,in a curved space.

we usually tend to think abou light travelling in straight lines,but general theory of relativity disproves the fact.here's how.
==============================================
according to theory of relativity(general)the effect is only due to the fact that light travels a hell lot faster.the flash of light to origin to the landing place of the balls would be so quick thats its path would be indistinguishable from the X-axis itself.the curvature of it in space-time would be same as that of balls.,thus paths of balls and beams of light are geodesics in space time curved by earth.any further clarifications and comments would be welcome.
==============================================
bye!

The energy and information about the pulse was stored in the quantum ensemble of atoms in that experiment. Was not that the point I was making ... or attempting to make?

Originally posted by Crisp
Hi all,

I agree with James R here, the only way to actually stop a photon is by absorption, leading to the destruction of the photon.

However, if - very hypothetically speaking, with some magic wink-wank - you could get a photon to stop, you wouldn't see anything. In order for you to see or detect an object, it has to emit ... light or photons. I still have to hear about photons emitting photons in order to be detected.

Bye!

Crisp

Crisp,

What about the slowing of light in a Bose-Einstein Condesate? It is possible to slow light down to very slow speeds, on the orders of miles / second in such material and it has even been proposed that if you create a BEC and then spin it somehow that you could potentially create a light "black hole" in which the ligth could not escape because its velocity in the medium would be slower than the rotational velocity of the medium.

Hi SeekerOfTruth,

"What about the slowing of light in a Bose-Einstein Condesate? It is possible to slow light down to very slow speeds, on the orders of miles / second in such material and it has even been proposed that if you create a BEC and then spin it somehow that you could potentially create a light "black hole" in which the ligth could not escape because its velocity in the medium would be slower than the rotational velocity of the medium."

In theory (if you consider the wave nature of light) you could do that yes, but that wouldn't mean that the light inside has "stopped" (eg. the photon is at rest, v = 0 and not v = c/n where n is the refraction index of the medium). Light is still propagating inside the medium, but slower than usual. On the other hand, it could be a bit problematic if you use the photon description of light: once a photon is absorbed by a boson of the BEC the boson moves forward and emits the photon again, so in that way I don't immediatelly see how the light could "lag" behind the matter. I guess the experiment should be done and tell us more about the nature of light :)

Bye!

Crisp

Chagur:

No problem. I was just giving a bit more information. Thanks for the links.


zion:

If two balls are travelling at different speeds, they <i>must</i> have different worldlines. For example, if we graph their position, <b>x</b> against time <b>t</b>, then the gradient of the line on the graph at any point is equal to the ball's speed. Different speeds mean different gradients and therefore different lines for the two balls.

Chagur,

Does the pulse of photons exiting the B-E condensate contain the same photons that initially entered it, or does the exiting pulse contain new photons recontructed from wavelength & pulselength information stored within the condensate while it was opaque to photons?

Does what usually happens to photons when they encounter conditions of severe opacity also occur within B-E condensates?

What role, if any, is played by electrons within the condensate that might affect the identities of photons when during the experiment the condensate is suddenly made to again become opaque?

Take care.

Darned if I know ...

Have you tried a Google search?

Take care ;)

Chagur,

Yes, I googled and still I'm left with my original suspicion that the photons coming out are not the same as went it, that indeed the originals were absorbed, converted into stored above-ground-state information that was then reconverted into new photons to permit the condensate to return to (truer) ground state.

I can't do the math so I am left with offering the innuendo.

Mr G, I think you are right. A BEC, when it comes down to it, is just another bunch of atoms, so it acts in many ways just like any bunch of atoms. (In other ways it acts more like <i>one</i> big atom, of course.)

I would say: BINGO!

If for no other reason than
" ... turn the coupling laser back on, and the pulse is reconstructed and emerges, propagating as if nothing has happened." which is what James R referred to in a prior post.

As far as
Does what usually happens to photons when they encounter conditions of severe opacity also occur within B-E condensates? I can not think of a reasonable alternative.

Take care. ;)

PS Wonder if thinking of photons as distinct entities rather than
energy which can be 'reconstructed' from the original information
doesn't contribute to the seeming problem? Just a thought.

I'm still going to say "Photoelectric effect".

<<...If for no other reason than...reconstructed...>>

Um, I wasn't basing my argument on simple semantics. Too easy.

I said previously that electrons stop only when they are absorbed by electrons. You then offered that they can also stop in Bose-Einstein condensates (slowed, anyway). So, I responded that Bose-Einstein condensates contain electrons and then further implied that photons entering such condensates will encounter electrons that will absorb them. To which you had a google's reply.

I also am quite aware that photons are not particles but packets of bundled interfering waves that could constructively interfer with the Bose-Einstein condensate wave function(s) and be represented within it by short-term wavefront interference patterns.

I was probing you, not the condensate. ;)

And no, I'm not an alien and you'll have to supply your own probative anal reward. :p

Now that we've 'probed' each other :)

Just so you understand where I'm at (not that you necessarily care) ...

No problem with your initial, 12/01 0908hr., response:
"It gets absorbed by an electron."

But then, when at 2139hr. you stated in a subsequent post:
"... the photon (apparently frozen in place within the sodium atom) ... "
The old antenna started vibrating and I responded.

Take care.

PS Use of expression 'antenna vibrating' metaphorical!

I herewith state under penalty of perjury:
I am not and never have (to the best of my knowledge) been an alien. ;)

What happens when light stops?


It looks both ways, and if nothing is coming, continues.

Originally posted by Chagur
"Recently, the Hau group succeeded in reducing the light speed to 17 m/s (the speed of a racing bicycle) by optically inducing a quantum interference in a Bose-Einstein condensate."

<a href=http://www.physics.harvard.edu/fac_staff/hau.html><font color=red>1999 Article</font></a>

2001

"The sample becomes opaque once more, and the light pulse cannot emerge."

<a href=http://www.nature.com/nature/fow/010125.html><font color=red>2001 Article</font></a>

My, doesn't time fly (and not "in a sodium atom")?

Take care.

I read an article in Scientific American called "frozen light" where it told about slowing light to the speed of a bike just like that article,

they were even able to store information in the light and when it got back up to speed it still had the info intact, though the longer they kept it the more it degraded,

hey I found the article I was just talking about after going to the scientific american site:

http://www.sciam.com/2001/0701issue/0701hau.html

Who says a photon doesn't have mass? It does have mass but it is different than regular matter. Regular matter creates a unipolar gravitational field at all sides. A photon, on the other hand, has a bipolar gravitational field, an anti-gravitational pole facing forward and gravitational pole facing back. That is how it's able to accelerate to light speed.

Tom

<i>A photon, on the other hand, has a bipolar gravitational field, an anti-gravitational pole facing forward and gravitational pole facing back. That is how it's able to accelerate to light speed.</i>

Do you have a reference for where I can read up on that theory? I'm unfamiliar with it.

James R,

There is no theory, it's just an assumption I made. I figured that a photon needs to create a force to accelerate. Since the electric and magnetic field of a photon are at right angles to the motion of the photon, it can't be them. It would have to be the gravitational field , since a photon reaches light speed in space where no other fields are present except the gravitational field. Now if you assume it is gravity that causes the photon to accelerate, you would have figure out the structure of the gravitational field around the photon. The only way a particle could accelerate to light speed using it's gravitational field would be if it's gravitational field was bipolar.

The problem with that is that photons don't accelerate. They are created travelling at the speed of light.

James R,

Obviously, when electrons emit photons the electrons are not moving at light speed. I also doubt that photons are actually bouncing off the inside of electrons at light speed before they are emitted. Therefore, the photons accelerate to light speed as soon as they are emitted.

Tom

Joeblow,

Your conclusions don't follow from your premises. No, the electrons are not travelling at light speed. But photons don't exist "inside" electrons - that's not how photon emission works. As I said, photons are created travelling at light speed.

James R,

You're not making sense.

Please explain how a particle(electron), moving at velocity much slower than light, can emit a second particle(photon), which travels at the speed of light, without the second particle having to accelerate to the speed of light. Is it magic!!??

Tom

I'm sure James R will differ in understanding, but from what I've deduced in theory, an electron is just a matrix of photons anyway. (A photon collaberation caused by blackhole acceleration/compression)

From the information I've obtained, what you see appears slower than it actually is. (thats why if an atom is split it releases so much energy)

I think how James R meant wasn't that a photon was absorbed, but it creates a Quanta Ripple that's re-applied during an impact.
(The Photo-Electric effect)

Of course feel free to correct.

Joeblow (can I call you Tom?),

<i>Please explain how a particle(electron), moving at velocity much slower than light, can emit a second particle(photon), which travels at the speed of light, without the second particle having to accelerate to the speed of light. Is it magic!!??</i>

As I said before, the photon does not exist inside the electron, so it doesn't have to travel at the same speed as the electron at any time. It is created travelling at the speed of light.

Any particle with zero rest mass is constrained to travel at the speed of light, always. It cannot slow down or speed up (accelerate) by any mechanism.


Stryderunknown:

An electron is not made up of photons.

Hi all,

I'd like to add something to James R's post:

"As I said before, the photon does not exist inside the electron, so it doesn't have to travel at the same speed as the electron at any time. It is created travelling at the speed of light."'.

Joeblow, what you are probably asking yourself is where the photon comes from then. The answer is quite simple actually: photons can be created from the energy the electron has. More important, the photon's speed is the same for all observers. This means that regardless of the speed of the object the photon originated from, it will always travel at lightspeed.

Stryderunknown,

Care to elaborate how you've come to the conclusion that electrons consist of photons ? At the moment, the general accepted theory is that the electron is one of the fundamental particles (along with the quarks and other leptons).

Bye!

Crisp

James R,

Sure you can call me Tom.

First, you still didn't explain how one particle which is not traveling at light speed can create a particle which is traveling at light speed without the created particle having to accelerate. As Crisp pointed out, the photon could have been created from the electron's electric field. If that was the case, the electric field would have to be composed of particles that are traveling at light speed already. Unfortunately, I believe the electric field of an electron is stationary, so Crisp's idea would not apply.

You also stated that since a photon has no rest mass, it must travel at light speed. Why can't a massless particle just float around?

Last but not least, this whole discussion is about the acceleration of photons. If you don't take the creation of a photon into consideration, a photon decelerates as it enters a denser material, such as glass, then accelerates back to light speed as it exits the material. What force do you believe causes this acceleration?

Tom

according to one Sansbury, things are quite different

Sansbury (http://users.bestweb.net/~sansbury/book98.htm)

the oscillations stop, that's it

Tom,

<i>As Crisp pointed out, the photon could have been created from the electron's electric field. If that was the case, the electric field would have to be composed of particles that are traveling at light speed already. Unfortunately, I believe the electric field of an electron is stationary, so Crisp's idea would not apply.</i>

The electric field is not made of particles. I don't really want to get into exactly what a field is right now, though, so let's stick with photons. Photons are created from <b>energy</b> that the electron has for whatever reason. That energy can be electromagnetic or kinetic, or some other type. Photons are not created inside the electron, since the electron (as far as we know) is structureless and dimensionless. Instead, photons are created out of the vacuum using the energy of the electron. They are created travelling at the speed of light.

<i>You also stated that since a photon has no rest mass, it must travel at light speed. Why can't a massless particle just float around?</i>

I'm not sure exactly, but feel free to check on my statement if you doubt me. Massless particles always travel at the speed of light. I'm pretty sure there are relativistic reasons for that. There is no such thing as a stationary photon.

<i>If you don't take the creation of a photon into consideration, a photon decelerates as it enters a denser material, such as glass, then accelerates back to light speed as it exits the material. What force do you believe causes this acceleration?</i>

Photons do not accelerate or decelerate in glass. What happens is that photons are constantly absorbed and re-emitted by glass atoms. There is some delay between absorption and re-emission, which means the photons take longer to pass through glass than they do to pass through a vacuum of the same length. Between glass atoms, photons travel at the usual speed - the speed of light in a vacuum.

Hi all,

"Massless particles always travel at the speed of light. I'm pretty sure there are relativistic reasons for that. There is no such thing as a stationary photon."

Indeed, a massless particle can always be reduced to a photon - since massless implies that the particle consists only of energy (which is manifested only as photons). We know that photons travel at lightspeed hence all massless particles travel at lightspeed ;).

"As Crisp pointed out, the photon could have been created from the electron's electric field. If that was the case, the electric field would have to be composed of particles that are traveling at light speed already. Unfortunately, I believe the electric field of an electron is stationary, so Crisp's idea would not apply. "

I never talked about an electric field. As James R correctly pointed out, I was refering to particle creation from whatever energy the electron might have. And also, electric and magnetic fields are observer-dependant, and only in the electron's frame of reference is its electric field stationary. All other observers will see an electric and magnetic fields produced by the electron.

Bye!

Crisp

Crisp,

"Indeed, a massless particle can always be reduced to a photon - since massless implies that the particle consists only of energy (which is manifested only as photons). We know that photons travel at light speed hence all massless particles travel at light speed"

You assume that since a photon doesn't have mass, it isn't matter. Gravity does not have to be a characteristic of all matter. You also didn't indicate why a massless particle must only travel at light speed.

This whole discussion is about a misunderstanding. You and James R believe that a photon is pure energy, and therefore can do "magical" things. I, on the other hand, believe that a photon is a particle, and is therefore it is matter, even though it's gravitational field is ignored(curved space crap). I believe that energy can't exist without matter, energy is a characteristic of matter. Therefore in order for the matter in a photon to reach light speed it must accelerate, or be created from matter that is already at light speed.

Tom

I on the other hand believe that mass is frozen energy (matter myth, Paul Davies)

Interesting article on “stopping light” in a crystal similar to BEC experiment.
http://www.nature.com/nsu/020107/020107-2.html

And here’s an amusing discussion of the article at SlashDot.
http://slashdot.org/science/02/01/08/2036212.shtml

Potential application to quantum computing?

Imahamster,

Interesting link. Maybe you can store energy this way(photonic battery).

Tom

Crisp:

I disagree that the photon is the only massless particle. What about gluons, for example? I also disagree that photons are "pure" energy, whatever that is. Photons are electromagnetic entities.


Tom:

<i>I, on the other hand, believe that a photon is a particle, and is therefore it is matter, even though it's gravitational field is ignored(curved space crap).</i>

A photon is a particle, but it is not matter. It is a gauge boson. Matter has (rest) mass. A photon should also have a gravitational effect, though a tiny one.

<i>I believe that energy can't exist without matter [etc.]</i>

I would say energy is a property of a <i>system</i>, not a particular particle of matter (e.g. consider potential energy).

Hi all,

James R,

"I disagree that the photon is the only massless particle. What about gluons, for example? I also disagree that photons are "pure" energy, whatever that is. Photons are electromagnetic entities. "

Hrm, didn't know that gluons have zero mass. I knew I shouldn't have skipped that part when studying for my elementary particles exam ;).

You say photon's are electromagnetic entities. Isn't this a bit circular reasoning ? An electromagnetic field consists of photons (e.g. the Coulomb force is mediated by photons), so defining photons as electromagnetical entities makes the definition of an electromagnetic field kinda hollow. However, I agree with your point that the term "pure energy" can be misleading; it is also not entirely what I meant to say in my previous post - I tried to point out that a photon only manifests itself in the form of energy, e.g. in absorption or emission phenomena. So IMHO for all practical purposes we can say that a photon consists of energy (even though energy is a fictous concept, something man made up for easing calculations). The deeper underlying structure can probably be found in QED with photonfields.


Tom,

"You assume that since a photon doesn't have mass, it isn't matter. "

Exactly. I consider matter to be objects that have restmass, which a photon doesn't have.

"Therefore in order for the matter in a photon to reach light speed it must accelerate, or be created from matter that is already at light speed. "

If matter were to travel at lightspeed, that would violate the theory of special relativity, which we assume to be correct. Concerning the acceleration of photons: Why should it accelerate in the first place ? A new particle is created, of which we know it travels at lightspeed. There's no need for acceleration complicating the description we have at the moment.

Bye!

Crisp

check out National Geographic, october 2001

Scientist Lene Hau brings a laser-beam to a stop with some kind of gas.

I read all the post and find it interesting, maybe you guys are interested in this
http://users.bestweb.net/~sansbury/book98.htm

homepage: http://users.bestweb.net/~sansbury/Index.htm

I've mentioned it already in another thread but it should be here actually

and yes I've read it myself and no I am not understanding it completely, but enough I think

Apparently not much...

http://www.nature.com/nsu/020107/020107-2.html

If light stops, time also stops. Also stops the expansion of space. All materials will be broken down to until the singularity. All substances will be transformed into energy states. This energy intensive fields are distributed equally everywhere in space, due to entropy law. It lasts, until all the frequencies will be at the equal level radiation. It is the return to previous period of big bang.:D

If light stops, time also stops. Also stops the expansion of space. All materials will be broken down to until the singularity. All substances will be transformed into energy states. This energy intensive fields are distributed equally everywhere in space, due to entropy law. It lasts, until all the frequencies will be at the equal level radiation. It is the return to previous period of big bang.:D
Congratulations Burtay, this is the oldest resurrection of a thread I've ever seen!

When the light of a more distant star passing near a massive object in space appears to curve it is not because the photons of light are responding to the nearby mass as if they themselves have mass. The photons are moving in straight-line paths. It is spacetime through which they are moving that is curved by the massive object nearby.

It is analogous to a spoon in a glass of water. It appears bent but is not physically bent.

The photon is moving straight. The mass is curving spacetime. The curvature of spacetime makes the photon's straight-line behavior appear to the outside observer to be curved as if in response to the mass, but the photon only knows it is moving straight.

More Einstein, less Newton.

it appears einstein said massive objects cause or are-in curved space time, meaning that gravity is a factor. yet he failed to tie gravity in his eqations.