Would it Feel as if Time Stopped If I Became Light?

[Phrak]

Can we get a sticky and a forum ban on the "photon perspective" topic? There must be 3/week of these, or more, and they all go the same way.

I find a great deal more fault with the answers than the question. What is wrong with simply claiming ignorance??

When something is not well understood it should be expected that the question is often ill posed. This should be understood. Instead, we use it as a shield. These threads tell me a lot more about psychology then physics.

"It makes no sense" is an honest answer. Though to demand that someone share ones ignorance goes a little too far.

 

[JesseM]

I find a great deal more fault with the answers than the question. What is wrong with simply claiming ignorance??

But it's not ignorance, it's a positive claim that the question makes no sense in the context of known theory (akin to 'what are a photon's political beliefs like'), since "what are things like from X's perspective" always means either "what are things like in X's frame" or "what do things look like visually for X", and neither makes sense for a photon since a photon can't have an inertial rest frame (and there's no physical reason to prefer any of the infinite number of non-inertial rest frames you could invent), nor does a photon have any internal processes that could be used to mark the time on different events on its worldline.

 

[Dale]

I agree with JesseM, it is not about ignorance. The statement e.g. that 5/0 is undefined means that there is no solution to the equation 5=0*x, it does not mean that there is a solution but just that we don't know what it is. Similarly, the statement that there is no inertial frame where a photon is at rest does not mean that there is one and we just don't know what it is.

 

[qwerty1]

I think I already know the answer, but a friend of mine disagreed with me on this point:

If I were to become light, i.e. my consciousness was transferred to a photon moving with speed c, would it then seem to me as if I existed outside of time? I think it would because of the fact that moving clocks seem to travel slower. If you do a time dilation calculation you get the time interval in the moving system to be infinite compared to the proper time interval. It seems to me as if you would paradoxically experience two different things:

1. The universe would stand still (i.e. time would stop) for the rest of eternity.

2. All events in the future would happen instantly.

I am curious about a similar question... If i were a monkey launched at nearly the speed of light would i still like bananas? or if i were going that fast would i want to eat crab meat?

the thing is you are asking what it would be like to be something that is not conscious... if you were "turned into a photon" i would imagine you would be dead and experience the same thing that dead people do... you might want to get some lab equipment like a Ouija board and ask the question that way... :P

 

[Phrak]

But it's not ignorance, it's a positive claim that the question makes no sense in the context of known theory (akin to 'what are a photon's political beliefs like'), since "what are things like from X's perspective" always means either "what are things like in X's frame" or "what do things look like visually for X", and neither makes sense for a photon since a photon can't have an inertial rest frame (and there's no physical reason to prefer any of the infinite number of non-inertial rest frames you could invent), nor does a photon have any internal processes that could be used to mark the time on different events on its worldline.

Xcrunner2414 deserves an award for perseverance; I haven't the stomach for this.

If you wish to advance your argument, rather than arguing somewhat randomly that nothing makes sense this way and that, you might discover what is formally indeterminate and what is not. But to insist that nothing is determinate is a very risky stance to take.

 

[Fredrik]

If you wish to advance your argument, rather than arguing somewhat randomly that nothing makes sense this way and that, you might discover what is formally indeterminate and what is not. But to insist that nothing is determinate is a very risky stance to take.

The arguments have been presented in all of the recent threads about this topic, and they're very solid. They're certainly not "random". If you think so, you haven't been reading carefully enough.

OK, qwerty1's argument about monkeys is kind of random, I'll grant you that.

(qwerty1: Atoms aren't conscious either, but we can still talk about their points of view. When we do, we're always referring to a description in terms of a coordinate system that can be associated with the particle's motion in a very natural way. The problem with photons is that the "natural way" to associate a coordinate system with the particle's motion doesn't work, and that a null geodesic can never be the time axis of an inertial frame).

 

[JesseM]

If you wish to advance your argument, rather than arguing somewhat randomly that nothing makes sense this way and that, you might discover what is formally indeterminate and what is not. But to insist that nothing is determinate is a very risky stance to take.

Only a formally-defined question can have a formally-defined answer like "formally indeterminate". "What are things like from a photon's perspective" is just a bunch of English words that don't have any clear technical meaning. My argument may have looked "somewhat random" to you but take note that I was listing different formal meanings that "perspective" might have (what things are like in the object's rest frame, what would be seen visually on the object's worldline) and explaining why, whichever you chose, the question would not have a determinate answer in relativity. If you'd like to offer some alternate possibilities for how the nontechnical word "perspective" might be interpreted I'm happy to hear it, but as the question stands, it's too vague to be have either a formally determinate or formally indeterminate answer, you might as well ask "how does a photon feel as it travels" ('feel' being an English word with no well-defined technical meaning, just like 'perspective')

 

[Phrak]

Perhaps I should have been discussing the limit as v approaches c.

Dividing by zero a few times and giving up does not mean something makes no sense. It just means we gave up. We can change to null coordinates where some things do make sense when v -->c, where the velocity of the frame is in the positive x direction:

a = x-ct
b = x+ct

The y and z coordinates remain unchanged.

In null coordinates the Lorentz transform takes a simple form.

V = sqrt[(1-(v/c)²/(1-(v/c)²]

a' = aV
b' = b/V

The map from b to b' is undefined. We have to divide by zeo.
The map from a to a' is determinate. Of course it's not very interesting. All of the a coordinate collapses to zero extent.

There may be other things that make sense such as the ratio between the null velocities of two particles.

 

[bapowell]

The fact that no inertial frame exists for the photon does not depend on the choice of coordinates. The fact that the Lorentz transformations are singular at v=c is a symptom of this deeper problem. Myself and others in this thread have been tirelessly saying this over and over for some time now.

 

[JesseM]

Dividing by zero a few times and giving up does not mean something makes no sense. It just means we gave up.

As bapowell said, the conclusion that photons cannot have an inertial rest frame does not have anything to do with "dividing by zero". It follows from the first postulate of SR, which says the laws of physics must have the same form in every frame defined as an "inertial" one. Since light cannot be at rest in any sublight inertial frame, the first postulate would be violated if there were an inertial frame where light was be at rest. Of course you can still define a coordinate system where light is at rest, but it's a non-inertial one.

 

[Dale]

As bapowell said, the conclusion that photons cannot have an inertial rest frame does not have anything to do with "dividing by zero". It follows from the first postulate of SR, which says the laws of physics must have the same form in every frame defined as an "inertial" one. Since light cannot be at rest in any sublight inertial frame, the first postulate would be violated if there were an inertial frame where light was be at rest.

It also follows from the second postulate of SR which says that light propagates at c in all inertial reference frames. Since light propagates at c in all inertial reference frames then any frame where it is at rest must be non-inertial.

 

[Fredrik]

a = x-ct
b = x+ct

Yes, it's true that there's a coordinate system that has the massless particle's world line as the 0th axis. (It is a valid coordinate system, even though it's not an inertial frame). But why would we want to define this to be "a photon's point of view"? The motivation for it wouldn't be the same as for the association of an inertial frame with the world line of a massive particle.

 

[phyti]

I think I already know the answer, but a friend of mine disagreed with me on this point:

If I were to become light, i.e. my consciousness was transferred to a photon moving with speed c, would it then seem to me as if I existed outside of time? I think it would because of the fact that moving clocks seem to travel slower. If you do a time dilation calculation you get the time interval in the moving system to be infinite compared to the proper time interval. It seems to me as if you would paradoxically experience two different things:

1. The universe would stand still (i.e. time would stop) for the rest of eternity.

2. All events in the future would happen instantly.

Neither.
If the Lorentz factor becomes indeterminate, i.e., the period is without a limit, it takes no effort to conclude 'the clock stops'. This does not falsify SR, no more than 1/0 falsifies algebra.
The result (as mentioned in a previous post), if the clock stops, so does everything else, including your brain. You would experience nothing, the same as death.

A simple answer would have been sufficient, and not 3 pages of ...whatever!
It's unfortunate that people get so focused on ideas that they lose perspective and comprehension on the simple issues. It isn't necessary to use a backhoe to plant a tulip bulb.

 

[bapowell]

phyti, I'm so glad you came and saved us all with your brilliant and tactful treatment of the problem.

 

[JesseM]

Neither.
If the Lorentz factor becomes indeterminate, i.e., the period is without a limit, it takes no effort to conclude 'the clock stops'.

What clock? There is no physically possible "clock" moving at the speed of light. You can't use the Lorentz transformation to conclude that a "clock stops" at the speed of light any more than you can use it to conclude that a clock's ticking rate becomes imaginary when it moves faster than light. Equations in physics often have some restricted domain of physically meaningful applicability, this is just another such case.

 

[atyy]

Perhaps what I'm asking, quite simply, is how light and time are related.

http://physics.nist.gov/cuu/Units/second.html
"The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom."

If we and a light beam are traveling in the same spatial direction, the light beam will overtake us, and we will "experience" the successive peaks and troughs of its waves, which we can use to mark time.

Does it matter which frequency of light we use? No, because all frequencies of light travel at the same speed past us.

If two light beams are traveling in the same spatial direction, will the peaks and troughs of one wave shift relative to the other wave? No, because all frequencies of light travel at the same speed past us. So unlike us, a light beam will not "experience" the successive peaks and troughs of another light beam. So in the sense of being able to use a light beam traveling in the same spatial direction to mark time, time will not pass for light.

 

[qwerty1]

The arguments have been presented in all of the recent threads about this topic, and they're very solid. They're certainly not "random". If you think so, you haven't been reading carefully enough.

OK, qwerty1's argument about monkeys is kind of random, I'll grant you that.

(qwerty1: Atoms aren't conscious either, but we can still talk about their points of view. When we do, we're always referring to a description in terms of a coordinate system that can be associated with the particle's motion in a very natural way. The problem with photons is that the "natural way" to associate a coordinate system with the particle's motion doesn't work, and that a null geodesic can never be the time axis of an inertial frame).

agreed, but time is really not relevant in his question... if you "became a photon" or "group of photons" and "transferred your consciousness" to it... nm that... my point was that he is not presenting anything of relevance... he is asking a ridiculous question for a personal argument... time would be completely irrelevant to this conscious particle or energy wave... it simply is... this fourth dimension has no bearing to it... so why pose this question... if you could be a conscious particle or wave or whatever, time would not likely work into your 'thinking'... we are, for lack of a better term, machines built to absorb data in a specific linear way... why we were built this way is beyond me... time and space are what they are, and will be what they will be... time and space just dictate where these things are...

i like to think of time like this: (and if anyone thinks i am an idiot, which i am, i would rather enjoy the flames...)

space is like a jello mold... inside of the jello mold are teeny tiny bits of fruit... the jello mold is strung on a piece of sting that i like to call time... the sting runs from one "magic point" ,the beginning, to another "magic point", the end... if you slide the jello mold left down the string all the little pieces of fruit move away from the center of the mold and in little circles until the dissolve when the reach "the end" if you slide the mold to the right they move exactly opposite until they all run together... so really the fruit bits don't perceive anything... they are fruit bits (particles/matter) and the little gaps they leave behind themselves or project in front of themselves don't care either (energy)... and i know i am retard and i know this is a serious over simplification... but still it makes sense to me as a special ed student...

 

[chiro]

http://physics.nist.gov/cuu/Units/second.html
"The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom."

If we and a light beam are traveling in the same spatial direction, the light beam will overtake us, and we will "experience" the successive peaks and troughs of its waves, which we can use to mark time.

Does it matter which frequency of light we use? No, because all frequencies of light travel at the same speed past us.

If two light beams are traveling in the same spatial direction, will the peaks and troughs of one wave shift relative to the other wave? No, because all frequencies of light travel at the same speed past us. So unlike us, a light beam will not "experience" the successive peaks and troughs of another light beam. So in the sense of being able to use a light beam traveling in the same spatial direction to mark time, time will not pass for light.

I think this is what the OP is getting at, that time does not pass for light. Also as other people have mentioned, finite differences contract to points as the velocity approaches light.

In this sense these two things are consistent with each other: if all of space contracts to a single point, then through an analogy of ds = vdt we get 0 = 0 which is consistent with finite distances contracting to points and also the fact that time doesn't pass for the photon.

I don't know about the other threads discussing this topic, but I think this is not a dumb question to ask personally.

 

[Fredrik]

I think this is what the OP is getting at, that time does not pass for light. Also as other people have mentioned, finite differences contract to points as the velocity approaches light.

And as other other people have mentioned, there's no good reason to think of this limit as a photon's point of view.

I don't know about the other threads discussing this topic, but I think this is not a dumb question to ask personally.

I don't think anyone thinks its a dumb question. All those comments about how this topic is an "extremely frequently asked question" and that maybe it should even be on the banned topics list, aren't a reaction to the question, but to the fact that we've all answered it 20 times already. I agree that we need a sticky about this one, and the twin paradox.

 

[bapowell]

Agreed. In any case, it appears the OP abandoned this thread many posts ago...

 

[atyy]

In this sense these two things are consistent with each other: if all of space contracts to a single point, then through an analogy of ds = vdt we get 0 = 0 which is consistent with finite distances contracting to points and also the fact that time doesn't pass for the photon.

I'm not very fond of "space contracting to a point" language. But your equation is close to dss=dtt-dxx=0. I'm only giving a very, very abbreviated explanation here, try looking up Minkowski metric, the spacetime interval, and null geodesics.

 

[phyti]

What clock? There is no physically possible "clock" moving at the speed of light. You can't use the Lorentz transformation to conclude that a "clock stops" at the speed of light any more than you can use it to conclude that a clock's ticking rate becomes imaginary when it moves faster than light.

-The poster is a biological clock. At c, he or any device obviously would cease to qualify as a clock. We could accelerate the person to within a fraction of c, to make it more 'real', and at least make him comatose.
How does anyone determine that a device has stopped, or are they wrong?

Equations in physics often have some restricted domain of physically meaningful applicability, this is just another such case.

- Like when the observer is measuring the length of an approching rod along the x-axis, and as he records it, the rod hits him between the eyes?

Some people are just curious and don't have the time or inclination to do detailed studies of certain subjects. If their question is simple then give a simple answer in terms they can understand. To know your subject is one thing. To impart understanding about the subject is another. The first does not imply the second.
If someone asks for the time of day, no need to instruct them on how a clock works!

 

[Dale]

And if somebody asks what 5/0 it is not our fault if he doesn't like the answer that the question is bad.

 

[JesseM]

-The poster is a biological clock. At c, he or any device obviously would cease to qualify as a clock.

It's not that he would cease to qualify as a clock "at c", it's that it's physically impossible to get him moving at c in the first place, since he is made out of particles with nonzero rest mass. If you are arguing that his clock would stop at c, I would say this is just as incorrect according to known laws of physics as saying he would become a bowl of petunias at c.

We could accelerate the person to within a fraction of c, to make it more 'real', and at least make him comatose.

Sure, but the question was about what happens at c, not at a fraction of c. Again, any question about how time passes for someone moving at c just isn't physically meaningful according to the current understanding of physics.

Equations in physics often have some restricted domain of physically meaningful applicability, this is just another such case.

- Like when the observer is measuring the length of an approching rod along the x-axis, and as he records it, the rod hits him between the eyes?

Perhaps you are being facetious, but no, the fact that the rod hits him in the eyes doesn't change the fact that the length contraction equation correctly gives the rod's length in his frame (regardless of whether he is able to measure that length or not).

If their question is simple then give a simple answer in terms they can understand.

And the simple answer in this case is that there is no well-defined notion of light's "perspective" in SR. Anyone who tries to give any definite answer to this question, like your answer that "the clock stops" at c, is probably just confused about the physics.

 

[mordechai9]

My area of study lately has been plasma physics, and I find it very interesting to ask myself "What would it be like to be one of the electrons (or ions) zooming around in the field?"

For a photon, at the speed of c, I don't know a lot about special or general relativity, but you can at least say a few things, can't you? Basically the intuition is that you would be moving through space very rapidly. I can't think of a lot else to say. Obviously your motion might terminate or change depending on your surroundings, like light in a rainbow being diffracted around in a big circle, and scattering off at different frequencies. You find yourself moving along gravitational geodesics, I think, but I'm not entirely sure how that's interpreted.

 

[Dav333]

Just a noob question. Can you speak about the reference frame of a fast moving electron at 99.9999999999 c?

Would the universe from its view in the forward direction be extremely short?

 

[Phrak]

The specter of inertial frames has been raised a dozen times in this thread despite complete irrelevance. Carry on.

 

[matheinste]

Just a noob question. Can you speak about the reference frame of a fast moving electron at 99.9999999999 c?

Yes we can, and in fact we are possibly moving at very very high speeds withe respect to other objects in the universe. The transformation equations apply to any subluminal speed is inserted into them.

I must plead ignorance of what does or does not happen phyically when we plug c into the equations. The usual answer is that we cannot theroretically achieve a relative speed of c. This is true. However if the result of the mathematics gave a definite answer in the limit as we approached c then perhaps we would have no qualms in venturing an opinion. But in this case the result is indeterminate and so we cannot extrapolate although we can get as close as we like.

It is of course tempting and, to me, not unreasonable to assume that the trend continues towards time "standing still" for the "stationary" observer and length in the direction of motion becoming zero for the "travelling" observer, and vice versa.

Although I am aware of the problem, or non problem, I have no definite answer but I do not worry about it as it is a scenario that is not going to happen.

Matheinste.

 

[JesseM]

The specter of inertial frames has been raised a dozen times in this thread despite complete irrelevance. Carry on.

So what do you think is relevant to defining a photon's perspective? Do you agree that there are an infinite number of distinct possible non-inertial frames in which a photon is at rest (with different definitions of simultaneity, distance, and time intervals) and none are preferred over any other by the laws of physics? If "perspective" isn't interpreted in terms of a coordinate system, how is it to be interpreted?

 

[phyti]

Anyone who tries to give any definite answer to this question, like your answer that "the clock stops" at c, is probably just confused about the physics.

What's the probability?

Light mediates all energy transfer, therefore processes slow down for moving objects,
which includes clocks. This is also the reason objects can't be accelerated to light speed.
By reason without LT, the processes must stop, a consequence of a constant and independent light speed.

'No well-defined notion of light's "perspective"' doesn't answer his question in the context he's asking, and allows him freedom to imagine anything.

The poster got a hypothetical answer to his hypothetical question, which shows that nothing physically meaningful happens.

Of the many posts I've read (including other forums), some in broken english, there are only a few that were not easily understood. I think some answers have more complexity than the question merits.

Can you give an answer in laymans terms without all the techno-babble of theory?