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Appearence of traveling at superluminal velocity

Mon 8 Jul, 2013 03:28 am
Hello I have a question. From my understanding if I were to travel at 99.99%+ of the speed of light time would slow down for me right? If my perception of time slows down then would my perception of the speed in which I am traveling at push in excess of the speed of light?
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Type: Question • Score: 12 • Views: 5,019 • Replies: 40
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laughoutlood

1
Mon 8 Jul, 2013 03:32 am
@mrpjspencer,
I'm massively inclined to wonder why you think your perception would be slower?
mrpjspencer

1
Mon 8 Jul, 2013 03:37 am
@laughoutlood,
Well from what I understand the closer you get to the speed of light, you the observer time slows down. So stationary objects outside the craft would appear to be moving faster relative to you.
rosborne979

2
Mon 8 Jul, 2013 03:42 am
@mrpjspencer,
No, because distances are also stretched or compressed such that your perception of everything stays the same. That's why the theory is called "relativity".
Ragman

2
Mon 8 Jul, 2013 04:11 am
@mrpjspencer,
0 Replies

mrpjspencer

1
Mon 8 Jul, 2013 04:37 am
@rosborne979,
I don't get that, why would distance stretch? Surely if you've 10 miles to travel from A to B it will always be 10 miles.
rosborne979

2
Mon 8 Jul, 2013 04:49 am
@mrpjspencer,
Part of Special Relativity states that not only does Time become distorted, but also Distance. But it's the distance as measured from the relative standpoint of the traveler, not the observer.
Ragman

1
Mon 8 Jul, 2013 08:51 am
@rosborne979,
And, speaking of relatives ... so, Mr Big Shot...how come you never call? You live so far away?
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maxdancona

1
Mon 8 Jul, 2013 09:27 am
@mrpjspencer,
No. Your understanding is incorrect. The idea of relativity is that speed has to be measured relative to something. If you are in a spaceship, you can say you are stopped no matter how fast I say you are moving.

Your perception if you were to travel at 99.99% of the speed of light (according to me) is no different than you perception if you were stopped (according to me).
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oralloy

1
Mon 8 Jul, 2013 04:01 pm
@mrpjspencer,
mrpjspencer wrote:
I don't get that, why would distance stretch? Surely if you've 10 miles to travel from A to B it will always be 10 miles.

Distance changes (in this case it would compress) because the speed of light cannot be exceeded.

If time slowed down for you to the extent that you could cross the galaxy in the space of a second, if the galaxy remained its normal size you would be going vastly faster than the speed of light.

However, when time slows down for you, distance also shrinks. And in my above example, from your perspective the galaxy would compress to a size where it would take a second to cross from one side to the other at light speed.
maxdancona

1
Mon 8 Jul, 2013 04:18 pm
@oralloy,
Completely wrong Oralloy,

In relativity, time never slows down for you. Time can slow down for other people, but it will never slow down for you.

That's one of the keys of relativity.

oralloy

1
Mon 8 Jul, 2013 07:52 pm
@maxdancona,
maxdancona wrote:
Completely wrong Oralloy,

In relativity, time never slows down for you. Time can slow down for other people, but it will never slow down for you.

That's one of the keys of relativity.

No. If you approach the speed of light, the passage of time will be different for you than it will be for those who are not traveling at that speed.

You could travel the length of the galaxy and experience the passage of only a single second, while people not traveling with you would experience the passage of 100,000 years.
maxdancona

1
Mon 8 Jul, 2013 08:45 pm
@oralloy,
But Oralloy, you are approaching the speed of light, as am I, from someone's perspective.

You are missing the "relative" part of the relativity. Relativity means that different observers have different perspectives (and measure different speeds and times and distances). The key is that every perspective is equally valid, so it is just as correct to say that you are going at 99% of the speed of light as it is to say that you aren't moving, or to say that you are moving at any speed.

Do you sense time slowing down for you?
farmerman

1
Mon 8 Jul, 2013 08:57 pm
@maxdancona,
travelling at light speed you keep tuning in older radio programs.
farmerman

1
Mon 8 Jul, 2013 08:57 pm
@maxdancona,
travelling at light speed you keep tuning in older radio programs.
0 Replies

Fil Albuquerque

1
Mon 8 Jul, 2013 09:22 pm
@farmerman,
how do you know ?
0 Replies

oralloy

1
Mon 8 Jul, 2013 11:28 pm
@maxdancona,
maxdancona wrote:
But Oralloy, you are approaching the speed of light, as am I, from someone's perspective.

You are missing the "relative" part of the relativity. Relativity means that different observers have different perspectives (and measure different speeds and times and distances). The key is that every perspective is equally valid, so it is just as correct to say that you are going at 99% of the speed of light as it is to say that you aren't moving, or to say that you are moving at any speed.

Only perspectives that do not change their inertial frame of reference are equal to each other. Once a perspective starts accelerating, it is no longer equal to a perspective that remains in its original inertial frame of reference.

But it wouldn't invalidate my reply to mrpjspencer even if it were true that all perspectives were equal. When two perspectives are equal to each other, contraction of distance still prevents the speed of light from being exceeded.

maxdancona wrote:
Do you sense time slowing down for you?

No. But it is unlikely that I have accelerated from my inertial frame of reference.

And if I have so accelerated, then the entire universe has accelerated right along with me. And in that case, time slowed down for the rest of the universe too and there is no noticeable change from my perspective.
maxdancona

1
Tue 9 Jul, 2013 04:54 am
@oralloy,
Oralloy, there is no absolute frame of refernce. You are confusing the word "inertial" with the term "absolute". It doesn't work that way. In one frame of reference, right now, you are moving at 99% of the speed of light. In another frame of reference, right now, you are not moving. They are both equally valid.

Your use of the "inertial frame of reference" complicates the picture because it brings in acceleration/deceleration. But it doesn't change the fact that each perspective is equally valid.

In the case you suggest one person observes that you started at rest and then accelerated to "near light speed". However, don't forget, that there will be another frame of reference where an observer would observe that you started at "near light speed" and then decelerated to zero.

Even considering acceleration (and inertial frames) it is still equally valid to say you are, right now, moving at 99% of the speed of light-- and that you are moving at 0% of the speed of light. Right now, both of these are valid (in equally valid frames of reference).

While you are accelerating, you will experience the acceleration. However accelerating from rest, or decelerating from a fast speed to rest, are indistinguishable (since they are two ways of experiencing the same phenomenon from different points of view).

Once you stop accelerating, there are still multiple frames of equally valid frames of reference-- in one of them you are going 99% of the speed of light, and the other you are motionless.
dalehileman

0
Tue 9 Jul, 2013 11:34 am
@mrpjspencer,
Quote:
Well from what I understand the closer you get to the speed of light, you the observer time slows down. So stationary objects outside the craft would appear to be moving faster relative to you.
Not sure Mrp what you mean by "moving faster," whether you're referring to the speed at which they appear to be passing or the speed at which their clocks seem to be going

It's a relative matter as others have probably already pointed out. You will feel entirely normal, while "stationary"objects passing by at nearly c will appear squeezed up together (in the direction of motion) though all their clocks have stopped.

However, let us suppose before you began your trip that all the "stationary" clocks in the Universe had been synchronized so that now you can read them as you pass by. If you're not familiar with the principles of Relativity, you might disbelieve your instruments: Judging by the mount of energy you had expended in reaching that speed and the disproportional advance in these readings, you might conclude you're (they're) traveling at a speed many times c
maxdancona

1
Tue 9 Jul, 2013 11:55 am
Let's make this simple.

Speed is relative. This means that for a value to have any meaning, you must specify (or imply) a frame of reference. That is you must say that you are moving at 100,000 miles/hour relative to something.

There are two ways to do this... one is to assume that you are the frame of reference (this means that you are stationary) or the Earth is the frame of reference (which for any discussion about velocities near the speed of light is the same thing).

The second is to specify what your frame of reference is. You can do this by saying something like "you are travelling at near the speed of light relative to Alpha Century". If you are not talking about an Earth frame of reference (which is generally implied), than that second phrase is mandatory or what you are saying makes absolutely no sense.

A lot of posts in this thread don't make much sense because they imply that there is some "absolute truth", a frame of reference in which you can say "I am going near the speed of light".

The truth is that in any space ship, going any speed relative to the Earth (or any other frame of reference), an observer inside that space ship will correctly say that they are motionless.

Saying that time slows down for you when you are "moving at near light speed" makes no sense at all, because if you are the observer, you are actually motionless in your frame of reference no matter who thinks you are moving at near light speed.

You may observe other things moving relative to you, but you will observe nothing due to your own speed because actually you aren't moving.

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