fastest and slowest you can travel through time

[levi]

I have not completely finished reading up on relativity but one thing I did discover is that 2 people can pass through time at different rates. My question is what is the biggest difference 2 objects can travel through time? Or in other words what is the slowest and fastest objects can travel through time? I assume the fastest is light but what is the slowest thing in time. Would the slowest thing also be the heaviest since light weighs the least? would light also be the hottest while the slowest thing be the coldest? Would light be lightest color while the slowest thing be darkest color? I am not the smartest person so try to keep your answer simple, thanks

 

[rjh01]

The slowest you can move though time would be if you regarded yourself at rest and were far from gravity. The fastest would be travelling close to the speed of light or at the edge of the event horizon of a huge black hole, when you would see the last stars burn out before you get to old age.

 

[Soapy Sam]

Is that not precisely backwards?
Surely at c you don't travel through time at all?

 

[beelzebub]

IANAP !
This is my understanding of things...

It depends on whether you are talking about special or general relativity. The 'twins-paradox' exists only in a special, inertial-frames situation with no acceleration (The two frames approach and pass by with no possibility of a return to compare notes - that would involve accelerations that would then make the frames non-inertial.

From your point of view, the apparent time passing in another inertial frame could vary from infinite (the frame is approaching you at the speed of light) all the way to zero (the frame is receding from you at the speed of light).
The other frame would, of course, see exactly the same apparent time passing in your frame (from their frames point of view).

This is not a paradox, as the two frames are purely inertial. It is acceleration that makes one frame unique to another - hence if you accelerated to very close to the speed of light, then deccelerated back down to zero speed (all relative to another inertial frame, the Earth, say) then you would have aged less than your stay-at-home twin.
If you could accelerate to the speed of light, even for a microsecond by your reckoning, then all of eternity would have passed by back home.

 

[marplots]

Levi,

Time is always measured at one second per second. It's the frame of reference that varies.

You might try an analogy (imperfect) with length. From a distance, your house looks no bigger than my thumb. But up close, it's bigger than an elephant. My perspective changes, length doesn't. In the frame of your house, it's big. In the frame of me-at-some-distance, I measure it as small.

See if you can get past the idea that there is some universal, standard time to compare with that will tell you time is moving faster or slower.

 

[DallasDad]

I'm not sure I understand the question. My first response was "one second per second" for both fastest and slowest. Other than subjectively, in what context does time pass at a different rate? Surely it's a function of what constant you want to hold in all but relativistic situations?

 

[Ziggurat]

I have not completely finished reading up on relativity but one thing I did discover is that 2 people can pass through time at different rates. My question is what is the biggest difference 2 objects can travel through time? Or in other words what is the slowest and fastest objects can travel through time?

There is no exact answer because this is actually not a well-formed question, though the reasons are not obvious to a beginner at relativity. So let me reformulate it into a related question which DOES have an exact answer.

Question: what is the shortest and longest time interval between two events?

Answer: The longest time interval between two events is the proper time for a straight line between them in space-time (which would correspond to the trajectory of a non-accelerating object). If the trajectory becomes curved, the time interval decreases, and the lower limit is zero for light-like trajectories.

Notice that this is sort of the reverse of Euclidean geometry, where straight lines are the shortest and curved lines are longer. Also, specifying two events is necessary to make the question meaningful. If you can grasp why, you've got a pretty good hold on special relativity.

 

[Crossbow]

I have not completely finished reading up on relativity but one thing I did discover is that 2 people can pass through time at different rates. My question is what is the biggest difference 2 objects can travel through time? Or in other words what is the slowest and fastest objects can travel through time? I assume the fastest is light but what is the slowest thing in time. Would the slowest thing also be the heaviest since light weighs the least? would light also be the hottest while the slowest thing be the coldest? Would light be lightest color while the slowest thing be darkest color? I am not the smartest person so try to keep your answer simple, thanks

Hello!

Sorry if I sound a bit negative, but I think that you need to study a bit more in order to ask better questions because I can develop several different responses to your questions since they are rather unlcear questions.

However, I would like to address the first point in your post that I underlined because it is a very good point to address.

You are quite correct in stating that different objects can pass through time at different rates.

Suppose for example that you had three perfectly accurate clocks that were in perfect synchoniztion. And one clock was sitting absolutely still that was not any affected by gravity in any way. In that case, that when that clock measured one second, it really would be one second. One hour, really would be one hour. One day, really would be one day. And so on.

Now then suppose, one of the clocks was moving just a bit below the speed of light, and it was not under the influence of gravity. As for that clock, one second would still be one second, one hour would still be one hour, one day would still be one day, and so on.

However, when time of the travelling clock is then compared to that of the stationary clock, then you would see that much more time had elapsed on the stationary clock than on the moving clock. But in both cases, the clock accurately recorded the time.

That is why it is called "Relativity" because the rate of time passage is relative to the speed at which the object is travelling.

By the same token, if the third clock was placed just outside of the event horizon of a black hole but not moving, then just like the travelling clock one second would still be one second, one hour would still be one hour, one day would still be one day, and so on.

But when the gravity clock is compared with the stationary clock, then one would see that much more time had elapsed with the stationary clock than with the gravity clock.

I know that is terribly simplistic, but it has been verified through actual experiments over many years and I hope it helps!

 

[AvalonXQ]

Consider the following:

"Person A and Person B are both sitting stationary in space. Suddenly Person B instantaneously accelerates to Velocity V and moves directly away from Person A. Person B later instantaneously accelerates again to approach Person A at Velocity V, and decelerates to Velocity 0 to again sit stationary next to her. When they check their watches, Person B shows 1 min to have elapsed, while Person A shows T mins to have elapsed."

For any value of T>1, there is a sublight value for V that makes the statement true according to relativity.

In other words, any relative rate of time is possible if unlimited accelerations and velocities (within the bounds of relativity) are allowed.

 

[Crossbow]

Consider the following:

"Person A and Person B are both sitting stationary in space. Suddenly Person B instantaneously accelerates to Velocity V and moves directly away from Person A. Person B later instantaneously accelerates again to approach Person A at Velocity V, and decelerates to Velocity 0 to again sit stationary next to her. When they check their watches, Person B shows 1 min to have elapsed, while Person A shows T mins to have elapsed."

For any value of T>1, there is a sublight value for V that makes the statement true according to relativity.

In other words, any relative rate of time is possible if unlimited accelerations and velocities (within the bounds of relativity) are allowed.

Ummmm, ...

If anyone wants to learn about Relativity (or physics in general), then I suggest that they ignore the above posting since there are so many things wrong with it.

 

[beelzebub]

Consider the following:

"Person A and Person B are both sitting stationary in space. Suddenly Person B instantaneously accelerates to Velocity V and moves directly away from Person A. Person B later instantaneously accelerates again to approach Person A at Velocity V, and decelerates to Velocity 0 to again sit stationary next to her. When they check their watches, Person B shows 1 min to have elapsed, while Person A shows T mins to have elapsed."

For any value of T>1, there is a sublight value for V that makes the statement true according to relativity.

In other words, any relative rate of time is possible if unlimited accelerations and velocities (within the bounds of relativity) are allowed.

Hi AvalonXQ,
First, A and B are not sitting "stationary in space", but rather, they are stationary with respect to their inertial frames of reference - there is no universal space reference frame (that went out along with the aether).
Second, it isn't usually helpful to invoke un-physical phenomena or actions when discussing physical events (ie instantaneous acceleration).

To answer the original question, just pay a quick visit to Wikipedia - there, less than a third way down the page is the equation you want

It is worth noting that this equation applies symetrically to both frames (so long as they remain inertial, of course).

 

[Metullus]

I thought you had to be sitting in a street car in Vienna...

 

[AvalonXQ]

If anyone wants to learn about Relativity (or physics in general), then I suggest that they ignore the above posting since there are so many things wrong with it.

I have a very good understanding of relativity -- or at least I believe I do. So if what I've said is wrong, it would be useful for you to explain why.

To address beelzebub's points -- perhaps "sitting in space stationary relative to each other" would have been clearer.

And "instantaneous acceleration" is a common simplification in special relativity. As has been mentioned with respect to the Twin Paradox, if the notion offends you, replace Person B with Persons B and C who never accelerate but are passing in opposite directions and synchronize their watches when they intersect.

The point is that, since the only limit to the time dilation experienced in the Twin Paradox is the speed of the leaving twin, any ratio of experienced time is possible if you permit sufficient sublight velocity and sufficient acceleration.

 

[Crossbow]

I have a very good understanding of relativity -- or at least I believe I do. So if what I've said is wrong, it would be useful for you to explain why.

To address beelzebub's points -- perhaps "sitting in space stationary relative to each other" would have been clearer.

And "instantaneous acceleration" is a common simplification in special relativity. As has been mentioned with respect to the Twin Paradox, if the notion offends you, replace Person B with Persons B and C who never accelerate but are passing in opposite directions and synchronize their watches when they intersect.

The point is that, since the only limit to the time dilation experienced in the Twin Paradox is the speed of the leaving twin, any ratio of experienced time is possible if you permit sufficient sublight velocity and sufficient acceleration.

Well, I have a fairly good understanding of Relativity as well, so here goes ...

First of all, I have never heard that term "instantaneous acceleration" used in Special Relativity, or anywhere else. While it true that acceleration can be quite rapid, it is never instanteous.

Therefore, a term like that should not be used.

Second of all, I do not like that idea of synchronizing watches as the travellers intersect. Such a thing is not terribly practical at relativistic speeds.

Therefore, that idea should be dropped.

Third of all, that idea that "any ratio of experienced time is possible" is quite incorrect. Because both General Relativity and Special Relativity state that time dilation does occur, and in some cases the amount of time dilation can be considerable, however it is time dilation all the same.

Therefore, a term like "any ratio of experienced time is possible" should be dropped because an uninformed individual (such as the person who started this thread) could be misled into thinking that one can use Relativity to travel backwards in time.

Fourth of all, acceleration really does not have anything to do with Special Relativity. Instead, what is important is the speed of the object in relation to the speed of light.

Therefore, references to acceleration should be dropped.

 

[beelzebub]

The Wikipedia page I previously linked to covers both Special and General Relativity solutions to time dilation - Unaccelerated frames, accelerated frames and gravitational frames.

 

[AvalonXQ]

"Rapid acceleration" would work as well as "instantaneous" and be more factually correct (although, similar to terms like "perfectly elastic" and "frictionless", the term is commonly used in the classroom to simplify these sort of thought problems).

As for your other considerations, you don't want to use synchronizations at relativistic velocities or accelerations at all? How do you propose explaining the twin paradox, then?

Finally, I actually said that any T>1 had a corresponding sublight V -- thus making it clear that I was not talking about negative or even fractional ratios. No time travel in my example; just a note that however different you want Person A and Person B to be, you can do it with sufficient velocity.

Next time you don't like an example, consider posting a revision that addresses your issues rather than making a blatant post that makes it sound like I said something in error (rather than using terms/simplifications you prefer to avoid).

 

[Crossbow]

"Rapid acceleration" would work as well as "instantaneous" and be more factually correct (although, similar to terms like "perfectly elastic" and "frictionless", the term is commonly used in the classroom to simplify these sort of thought problems).

As for your other considerations, you don't want to use synchronizations at relativistic velocities or accelerations at all? How do you propose explaining the twin paradox, then?

Finally, I actually said that any T>1 had a corresponding sublight V -- thus making it clear that I was not talking about negative or even fractional ratios. No time travel in my example; just a note that however different you want Person A and Person B to be, you can do it with sufficient velocity.

Next time you don't like an example, consider posting a revision that addresses your issues rather than making a blatant post that makes it sound like I said something in error (rather than using terms/simplifications you prefer to avoid).

Thanks for clarifying things somewhat, but I still think that you miss an important point which is that the poster who started this thread needed some good basic data. And if one is dealing with a person who is already rather familiar with Relativity, then such a person can parse out your statements and fill in the varous gaps; however, your statement was not well suited for describing time dilation to someone is not already familiar with Relativity.

As for what you suggest that I do in the future well I have news for you, I already did do it.

In fact, the post right before yours (#8) does address the issues I raised but I suppose that even someone with your keen eye for details missed it.

 

[AvalonXQ]

Suppose for example that you had three perfectly accurate clocks that were in perfect synchoniztion. And one clock was sitting absolutely still that was not any affected by gravity in any way. In that case, that when that clock measured one second, it really would be one second. One hour, really would be one hour. One day, really would be one day. And so on.

Now then suppose, one of the clocks was moving just a bit below the speed of light, and it was not under the influence of gravity. As for that clock, one second would still be one second, one hour would still be one hour, one day would still be one day, and so on.

However, when time of the travelling clock is then compared to that of the stationary clock, then you would see that much more time had elapsed on the stationary clock than on the moving clock. But in both cases, the clock accurately recorded the time.

That is why it is called "Relativity" because the rate of time passage is relative to the speed at which the object is travelling.

By the same token, if the third clock was placed just outside of the event horizon of a black hole but not moving, then just like the travelling clock one second would still be one second, one hour would still be one hour, one day would still be one day, and so on.

But when the gravity clock is compared with the stationary clock, then one would see that much more time had elapsed with the stationary clock than with the gravity clock.

If anyone wants to learn about Relativity (or physics in general), then I suggest that they ignore the above posting since there are so many things wrong with it.

Thanks.

 

[Complexity]

As I understand it, everything moves through spacetime at the same rate.

If something moves through the space aspect of spacetime more quickly, it moves through time more slowly.

(I know the words are confusing, because they all seem to involve a motion with respect to time.)

Thus, a photon, which moves at the ultimate limit c, does not experience time and does not age.

The closer that the speed of something in space approaches c, the more slowly it experiences time.

Paraphrasing and confusing, I'm sure.

 

[Crossbow]

If anyone wants to learn about Relativity (or physics in general), then I suggest that they ignore the above posting since there are so many things wrong with it.

Thanks.

So what is wrong with that post you quoted?

 

[AvalonXQ]

So what is wrong with that post you quoted?

First of all, I have never heard that term "perfectly accurate" used in Special Relativity, or anywhere else. While it true that clocks can be quite accurate, they are never perfect.

Therefore, a term like that should not be used.

Second of all, I do not like that idea of comparing the time of a clock within an event horizon with a clock experiencing no gravitational forces. Such a thing is not terribly practical with relativistic masses.

Therefore, that idea should be dropped.

Third of all, the idea of a "traveling clock" and a "stationary clock" is quite incorrect. There is no absolute reference frame, and the two clocks are in fact indistinguishable by the basic principles of Special Relativity.
Therefore, terms like "traveling clock" and "stationary clock" should be dropped because an uninformed individual (such as the person who started this thread) could be misled into thinking that one can use Relativity to preference one inertial reference frame over another.

Fourth of all, gravity really does not have anything to do with Special Relativity. Instead, what is important is the speed of the object in relation to the speed of light.

Therefore, references to gravity should be dropped.

 

[Crossbow]

First of all, I have never heard that term "perfectly accurate" used in Special Relativity, or anywhere else. While it true that clocks can be quite accurate, they are never perfect.

Therefore, a term like that should not be used.

Second of all, I do not like that idea of comparing the time of a clock within an event horizon with a clock experiencing no gravitational forces. Such a thing is not terribly practical with relativistic masses.

Therefore, that idea should be dropped.

Third of all, the idea of a "traveling clock" and a "stationary clock" is quite incorrect. There is no absolute reference frame, and the two clocks are in fact indistinguishable by the basic principles of Special Relativity.
Therefore, terms like "traveling clock" and "stationary clock" should be dropped because an uninformed individual (such as the person who started this thread) could be misled into thinking that one can use Relativity to preference one inertial reference frame over another.

Fourth of all, gravity really does not have anything to do with Special Relativity. Instead, what is important is the speed of the object in relation to the speed of light.

Therefore, references to gravity should be dropped.

'AvalonXQ' you do not know what you are talking about, and I expect that you never be able to understand what it is that you are talking about, therefore I will no longer try to explain this issue to you.

 

[Ziggurat]

Crossbow and AvalonXQ:

Your pissing match is getting annoying. I can tell that you both have reasonable familiarity with relativity, but also that neither of you actually works in the field. If you don't like the way that someone else framed a problem (and that really is the basis for your mutual objections), then find a way to do so without accusing the other person of being an idiot. Because the stupidest things either of you has said here hasn't been about relativity.

 

[AvalonXQ]

Crossbow and AvalonXQ:

Your pissing match is getting annoying. I can tell that you both have reasonable familiarity with relativity, but also that neither of you actually works in the field. If you don't like the way that someone else framed a problem (and that really is the basis for your mutual objections), then find a way to do so without accusing the other person of being an idiot. Because the stupidest things either of you has said here hasn't been about relativity.

Thank you for stating the obvious; I entirely agree. In fact all I did was use Crossbow's pedantry on his own post -- which he didn't have the presence of mind to realize.

If we're done with the pointless bickering, maybe the OP will return to clarify whether the explanations have sufficed for the questions raised.

 

[AvalonXQ]

'AvalonXQ' you do not know what you are talking about, and I expect that you never be able to understand what it is that you are talking about, therefore I will no longer try to explain this issue to you.

I still think that you miss an important point which is that the poster who started this thread needed some good basic data. And if one is dealing with a person who is already rather familiar with Relativity, then such a person can parse out your statements and fill in the varous gaps; however, your statement was not well suited for describing time dilation to someone is not already familiar with Relativity.

 

[Crossbow]

Crossbow and AvalonXQ:

Your pissing match is getting annoying. I can tell that you both have reasonable familiarity with relativity, but also that neither of you actually works in the field. If you don't like the way that someone else framed a problem (and that really is the basis for your mutual objections), then find a way to do so without accusing the other person of being an idiot. Because the stupidest things either of you has said here hasn't been about relativity.

Thanks much 'Ziggurat'! You are quite correct.

I will make evey effort to follow your advice in the future.