Are time and light at the same speed?

[adafus]

TL;DR

I guess it's probably a silly question but i was wondering about it in quite some time now, if you go (hypothetically) faster than the speed of light, time itself will not exist for you. Doesn't that means that the light is moving in the same speed as the time itself? That could be the reason of the constant of the light too, or am i thinking too high?

I'm probably am wrong in this but i guess you guys could light me in this one

 

[PeroK]

Summary:: I guess it's probably a silly question but i was wondering about it in quite some time now, if you go (hypothetically) faster than the speed of light, time itself will not exist for you. Doesn't that means that the light is moving in the same speed as the time itself? That could be the reason of the constant of the light too, or am i thinking too high?

I probably am wrong in this but i guess you guys could light me in this one

It doesn't make much sense to talk about the speed of time. Speed is generally the rate of distance/time. What would "the speed of time" even mean?

 

[adafus]

It doesn't make much sense to talk about the speed of time. Speed is generally the rate of distance/time. What would "the speed of time" even mean?

Well it could measure the speed of the expansion in the universe i guess, like if the time is a dimension and the universe itself is what creates the others dimensions of space, it could as well in it be the same speed as it moves, something like that.

 

[adafus]

Correct me if I'm wrong please

 

[PeroK]

Well it could measure the speed of the expansion in the universe i guess,

The expansion of the universe is measured in speed/distance as in $70km/s$ per Mega parsec. Or thereabouts.

 

[adafus]

The expansion of the universe is measured in speed/distance as in $70km/s$ per Mega parsec. Or thereabouts.

I see... then it doesn't go in the way i thought, i will think more about it

 

[adafus]

The expansion of the universe is measured in speed/distance as in $70km/s$ per Mega parsec. Or thereabouts.

I know this can be dumb but, when light is travelling, this $70km/s$ remain the same? Or the speed of the expansion of the universe is a constant as well?

 

[adafus]

I'm talking about turning the light itself as the reference frame

 

[Ibix]

I'm talking about turning the light itself as the reference frame

That makes no sense. Even trying to interpret it as a question about the rest frame of light makes no sense, since light can never be at rest and cannot have a rest frame.

 

[PeroK]

I know this can be dumb but, when light is travelling, this $70km/s$ remain the same? Or the speed of the expansion of the universe is a constant as well?

Light travels through vacuum locally at the speed $c$: that means as measured by a local observer. If a light signal travels through an expanding universe then the light is always moving locally at $c$, but the total time to get from point A to point B depends on the expansion of the space between A and B.

The universe expansion is not constant. At the moment it is thought to be accelerating, which means that the expansion rate is increasing.

 

[adafus]

That makes no sense. Even trying to interpret it as a question about the rest frame of light makes no sense, since light can never be at rest and cannot have a rest frame.

Well in my head it was different, i thought about if we put the light as reference frame the speed of the universe expansion would go up or something like that, guess I'm wrong then, still fun to wonder about.

 

[adafus]

Light travels through vacuum locally at the speed $c$: that means as measured by a local observer. If a light signal travels through an expanding universe then the light is always moving locally at $c$, but the total time to get from point A to point B depends on the expansion of the space between A and B.

The universe expansion is not constant. At the moment it is thought to be accelerating, which means that the expansion rate is increasing.

Yeah i studied that, and how the time slow down to make the light travel at the same time even with the space itself bending, but i just don't quite understand why just photons can make this, why photons itself need to travel at such speed and why is time bending within it, so i just thought that maybe the question was is not the light that needs to travel at the smallest distance, but time itself, or something like that

 

[adafus]

I don't know how much English mistakes i made so far, so, apologies

 

[PeroK]

Yeah i studied that, and how the time slow down to make the light travel at the same time even with the space itself bending, but i just don't quite understand why just photons can make this, why photons itself need to travel at such speed and why is time bending within it, so i just thought that maybe the question was is not the light that needs to travel at the smallest distance, but time itself, or something like that

I think you are confusing gravity with universe expansion. Modern cosmology is built on General Relativity, which is well understood in terms of the paths of light through spacetime.

That the local speed of light is always $c$ is a postulate of relativity. It can't be proved or explained, as such, but it can be confirmed by observation.

 

[adafus]

I think you are confusing gravity with universe expansion.

oh no, i guess I'm just confusing myself because I'm not good at giving examples, i understand well the diference between gravity and universe expansion (I'm a bit ashamed of myself for looking like i don't), the thing is that i am trying to make correlation about this two things, like , ''why when space bends the examples we use are about how the light is traveling and not about how TIME is travelling'' and ''The universe expanded and keeps accelerating, but it start expanding at the same time as the time itself, so is time accelerating?'', And if the time is accelerating, how could we know? Because we are traveling within it.
Guess this is where I'm trying to get.

 

[A.T.]

Summary:: I guess it's probably a silly question but i was wondering about it in quite some time now, if you go (hypothetically) faster than the speed of light, time itself will not exist for you. Doesn't that means that the light is moving in the same speed as the time itself? That could be the reason of the constant of the light too, or am i thinking too high?

There is a geometrical interpretation of Relativity similar to what you describe:

https://diagonalargument.com/2019/09/15/epstein-relativity-diagrams/

In this interpretation, everything (not just light) advances at the same rate in space-propertime. Only the direction with respect to the space and propertime axes is different. So if you are at rest in space, then you are advancing at the same rate thought propertime, as light is advancing through space.

 

[adafus]

There is a geometrical interpretation of Relativity similar to what you describe:

https://diagonalargument.com/2019/09/15/epstein-relativity-diagrams/

In this interpretation, everything (not just light) advances at the same rate in space-propertime. Only the direction with respect to the space and propertime axes is different. So if you are at rest in space, then you are advancing at the same rate thought propertime, as light is advancing through space.

Thanks, i will take a look, but is kinda strange, why we just see the rest in space and not in time? Am i getting into a misconception about thinking that time is a dimension as well?

 

[PeroK]

oh no, i guess I'm just confusing myself because I'm not good at giving examples, i understand well the diference between gravity and universe expansion (I'm a bit ashamed of myself for looking like i don't), the thing is that i am trying to make correlation abut this two things, like , ''why when space bends the examples we use are about how the light is traveling and not about why TIME is travelling'' and ''The universe expanded and keeps accelerating, but it start expanding at the same time as the time itself, so is time accelerating?'', And if the time is accelerating, how could we know? Because we are traveling within it.
Guess this is where I'm trying to get.

Imagine drawing two spacetime axes ($x$ and $t$, say). You can plot the worldline of a particle or light ray and it makes sense to talk about the motion of the particle or light ray.

But, it makes no sense to talk about time moving. Your coordinate axes provide a reference frame in which motion may be described.

Spacetime curvature (including the concept of an expanding universe) is described by the notion of a distance (metric) between any two points in spacetime.

 

[adafus]

''How can you be moving if you are at rest in a chair? You are moving through time. '' This is what Einstein said, this makes me think even more that time and light move at the same speed, but i just don't have proof yet i guess

 

[weirdoguy]

this makes me think even more that time and light move at the same speed

You've already been told that this does not make any sense. Why are you repeating it?

 

[PeroK]

''How can you be moving if you are at rest in a chair? You are moving through time. ''

You're also spinning with the surface of the Earth, orbiting the Sun and orbitting the galactic centre. Your watch is always ticking, that's true.

 

[adafus]

You've already been told that this does not make any sense. Why are you repeating it?

I don't think that just by don't understanding completely makes me wrong, maybe i just can't proof it yet, I'm looking at it in new ways, i will not surrender about it yet

 

[A.T.]

Am i getting into a misconception about thinking that time is a dimension as well?

In relativity you have two different time quantities:
- coordinate time, measured by a clock at rest in the used reference frame
- proper time, measured by a clock moving with each object

 

[weirdoguy]

I don't think that just by don't understanding completely makes me wrong

It makes you wrong because statement "time and light move at the same speed" makes no sense to begin with. Time is not a "thing" that moves anywhere. So there is no "speed of time".

 

[adafus]

In relativity you have two different time quantities:
- coordinate time, measured by a clock at rest in the used reference frame
- proper time, measured by a clock moving with each object

View attachment 272651
View attachment 272652

Is it the same time dilation that is learned in school right?

 

[adafus]

Light is not a "thing" that moves anywhere. So there is no "speed of time".

Is not a thing but yet it exist as a property, and so does time

 

[weirdoguy]

Is not a thing but yet it exist as a property, and so does time

Sorry, I corrected my post. I meant "Time is not a "thing" that moves anywhere. So there is no "speed of time"." Light is a thing, it's electromagnetic wave and it definitely moves.

 

[PeroK]

Is not a thing but yet it exist as a property, and so does time

Light is electromagnetic radiation; and time is not electromagnetic radiation!

 

[A.T.]

Is it the same time dilation that is learned in school right?

Yes, it's the same formula, just visualized geometrically.

In the usual Minkowski diagram you have the coordinate time on the vertical axis, and no direct visualization of proper time.

 

[adafus]

Sorry, I corrected my post. I meant "Time is not a "thing" that moves anywhere. So there is no "speed of time"."

don't change my response, is not a thing but is a propriety, gravity not exist as well but doesn't mean that we can't measure, i just saying that maybe we're looking at time and light as almost the same thing when we need to measure it