What Happens to Time When Traveling Near the Speed of Light?

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SUMMARY

The discussion centers on the implications of traveling at or near the speed of light, specifically addressing the effects on time experienced by the traveler compared to those remaining on Earth. Participants clarify that a body with non-zero rest mass cannot achieve light speed, making the original question nonsensical. However, they explore hypothetical scenarios where a traveler approaches light speed, revealing that significant time dilation occurs, allowing the traveler to experience much less time than those on Earth. For instance, if a traveler journeys at 0.99999c for a round trip of 20 light years, they may only experience a month while over 20 years pass on Earth.

PREREQUISITES
  • Understanding of Einstein's Theory of Relativity
  • Familiarity with Lorentz transformations
  • Basic knowledge of time dilation and its mathematical implications
  • Concept of proper time versus coordinate time
NEXT STEPS
  • Study the mathematical form of Lorentz transformations in detail
  • Explore the concept of time dilation through practical examples and calculations
  • Research the implications of the twin paradox in relativity
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USEFUL FOR

Physicists, students of relativity, science enthusiasts, and anyone interested in the theoretical implications of high-speed travel on time perception.

  • #31
What is the difference between the original one and the copy? It is not the information they are made of - that is identical. The difference is that the copy occupies another space in time - and in order to do that it must have traveled there somehow. The speed at which it traveled there is the speed of light.

If you want to say that the copy is indeed the new one then you'd just have to kill the original one.I guess you may be able to argue that the time it takes to construct the copy could account for the 'traveling at the speed of light' discrepancy. That is a possible argument I can see.
 
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  • #32
Ascending One said:
What is the difference between the original one and the copy? It is not the information they are made of - that is identical. The difference is that the copy occupies another space in time - and in order to do that it must have traveled there somehow. The speed at which it traveled there is the speed of light.

If you want to say that the copy is indeed the new one then you'd just have to kill the original one.





I guess you may be able to argue that the time it takes to construct the copy could account for the 'traveling at the speed of light' discrepancy. That is a possible argument I can see.


I inspect the chair that I'm sitting on, note the schemetics and write them down. I then encode them into a beam of light and send this to an alien civilization 100 light years away. When they receive the signal, they build a chair.

Did my chair travel at the speed of light?
 
  • #33
I don't see why not for all practical purposes.

No - the matter of the chair was not accelerated to the speed of light. But the information which represents the chair did travel at the speed of light and then that information was reconstructed... so in a manner of speaking yes it did travel at the speed of light.
 
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  • #34
Ascending One said:
I don't see why not for all practical purposes.

No - the matter of the chair was not accelerated to the speed of light. But the information which represents the chair did travel at the speed of light and then that information was reconstructed... so in a manner of speaking yes it did travel at the speed of light.

So, the information traveled at the speed of light (and carried by the light itself), not the chair, not you : This is a fundamental difference.

Xori said:
I disagree that this would be equal to traveling at the speed of light. This is simply a copy of you reconstrcuted somewhere, not the original you. If it is you, then you are capable of being in more than one place at the same time (the original you is here and the recontructed you is on the other planet)

he forgot to tell that the original him should be killed lol.

ahum.
This would not be traveling at the speed of light, just copying.
Just for the record, the amount of data to be transferred would be tremendous.
If it was to be stored in computer discs, possibly the pile of disks would be longer than the milky way. Not talking about the incertainty of capturing that data in the POV of quantum physics.

hamza said:
I wanted to ask that if a person returned home after a journey at the speed of light for a little while ; what will be the time at his home. I mean would all his relatives be dead by that time or would just a second have passed.

It has been already said, no object with rest mass can reach the speed of light, only approch it, and good answear has been given for that.
Another point that has lready been said: in the impossible event that an object could read the speed of light, the time of that object stops. Saying that, you can imagine that the universe would come to an end before the person (object) slows down and come back to see his family.

-----------------------------------------------------
Correct me if I am wrong.
http://ghazi.bousselmi.googlepages.com/présentation2
 
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  • #35
I never said the original should be killed.

Anyway, my point was not to illustrate a scenario where matter could be accelerated to the speed of light. It was rather an illustration of a manner where you could travel at the speed of light. It would merely be your information - not your physical substance. From a practical perspective, I don't see much of a difference. At least not a difference that my mom would be able to tell.
 
  • #36
It terms of physics, that's a primordial difference, what you are describing is a cloning machine that transfers information in the speed of light.
And this is not the same as saying that cloned object traveled at the speed of light.
I'm not discussion the feasability of this machine.
But the issue here was about "MATTER CANNOT travel at the speed of light".

-----------------------------------------------------
Correct me if I am wrong.
http://ghazi.bousselmi.googlepages.com/présentation2
 
  • #37
ok, ok... so, it's copying - and there's a primordial difference. I have a question then. How big of a difference is that? Is it significant - and how would you even measure that?

Also, someone said earlier that "you" can travel at the speed of light if you dove into the sun. Is that a correct assumption? If it is, then how would that happen? I assume you would burn to a crisp and then I guess turn into light?

So - following that logic... is there anyway hypothetical way that you could instantly be turned into light without burning or basically, without losing the information that makes up your physical formation? Because in that sense - wouldn't you be able to travel at the speed of light if you were then able to be reconstructed from that information at some other location?
 
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  • #38
Ascending One said:
ok, ok... so, it's copying - and there's a primordial difference. I have a question then. How big of a difference is that?
It's huge.

The difference between moving something and making a duplicate of something is ... well it's the difference between the pre-digital age and the digital age.
 
  • #39
It is a huge diffence. You're delving into a philosophical discussion of whether one's consciousness could be reconstructed with the perfect cloning machine. However, the atoms that make up your body would remain here, and therefore you would not be traveling at the speed of light.


I'm pretty sure if you dove into the sun you would still remain in the form of matter, not energy, and would therefore not reach the speed of light.
 
  • #40
What if the matter that made up your body was annihilated by antimatter? I believe that would be a way to instantly turn your matter into light - as gamma rays are emitted when that happens.
 
  • #41
Ascending One said:
What if the matter that made up your body was annihilated by antimatter? I believe that would be a way to instantly turn your matter into light - as gamma rays are emitted when that happens.
Sure. All of which would fly apart at c.
 
  • #42
Again, the issue was "MATTER can't travel at the speed of light", not turning matter into energy (by any exotic means suggested in the thread until now) that can travel at the speed of light, then hypoteticall reconstruct the matter or whatever.

This thread is deviating from its purpose.
Moderators, please close the thread.

-----------------------------------------------------
Correct me if I am wrong.
http://ghazi.bousselmi.googlepages.com/présentation2
 
  • #43
tabchouri - no disrespect - I don't think there's much purpose behind answering the question as literally as you're interpreting it. I think that in order to purposefully answer a question like that - it requires a bit of imagination. The answer to the question you're describing has a simple and quite definite answer. Who likes or wants that?
 
  • #44
Mentz114 said:
The light going close to the planet would be delayed compared with light that traveled from the same point to the receiver if the planet wasn't there. That's a clumsy sentence but I think about right. Experiments have been done to measure the delays caused by large bodies in the solar system.

But light speed is always measured the same by local observers. It does not make a lot of sense to talk about the speed of light somewhere/somewhen else because we cannot measure said speed.

Hello; Mentz
If I understand you then an observer on Earth say would see a different in when the light arrives depending on whether a planet had bent the light, but the light itself hasn't changes speed, it took a detour a longer path to get to earth.
I don't understand your comment that the speed of light from somewhere/somewhen else because we can't measured the speed of light. My understanding is that the speed of light has been measured pretty accurately using a rotating mirror.

Heather
 
  • #45
Heather,
but the light itself hasn't changed speed, it took a detour a longer path to get to earth.
Yes, I'm pretty sure that's what GR tells us.

The speed of light can indeed be measured at some location we have access to. But can we be sure that light traveling from one star to another is going at the same speed ? It's a whole different arena. It is a principle of special relativity that if we took our clocks and rulers to another galaxy and used them to measure the speed of light, we'd get the same answer as we got here.
 
  • #46
hi everybody!
okyae! from few days m wondering on a question, could anybody help me to understand it..
this is just a pure though experiment

if there was a Photonic camera( or let's say I travel in the speed of light) and is traveling in a speed of light, then how would it see two object on Earth one stationary and another moving car? i mean what is the relative velocity of the car and the man with respect to light...

i understand that no matter in what speed we travel , we see the speed of light be constant.

thankx
 
  • #47
eminent_youtom said:
hi everybody!
okyae! from few days m wondering on a question, could anybody help me to understand it..
this is just a pure though experiment

if there was a Photonic camera( or let's say I travel in the speed of light) and is traveling in a speed of light, then how would it see two object on Earth one stationary and another moving car? i mean what is the relative velocity of the car and the man with respect to light...

i understand that no matter in what speed we travel , we see the speed of light be constant.

thankx

Neither you nor your camera can travel at the speed of light. Even in principle, even in a thought experiment. Period.

Rephrase your question so that they are traveling near the speed of light.
 
  • #48
DaveC426913 said:
Neither you nor your camera can travel at the speed of light. Even in principle, even in a thought experiment. Period.

Rephrase your question so that they are traveling near the speed of light.

thanks Dave!
OK :redface: then how did Einstein do his thought experiment supposing, if I travel on the speed of light, will I be able to see the stationary ray of light ??


anyway.. let's edit my question..
if I travel on .99999999c and view on the surface of earth, where one car is moving with .2c velocity and another car is moving in the (both are moving away from light) .5c velocity ...

what is the speed of CAR1 and CAR 2 RELATIVE TO ME..

" I know that the relative velocity of light w.r.t both car is 'C' ".
thanks
 

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