# Faster than time

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#### Duke

• 38
##### Faster than time
« on: June 26, 2006, 07:45:46 AM »
Is it true that if you were going from Earth to space with the speed of light for several seconds and then go back on Earth you would see that several days have passed?
f you can't make it, fake it.

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#### Erasmus

• The Elder Ones
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##### Faster than time
« Reply #1 on: June 26, 2006, 08:35:35 AM »
Maybe.
Why did the chicken cross the Möbius strip?

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#### troubadour

• 551
##### Re: Faster than time
« Reply #2 on: June 26, 2006, 10:58:06 AM »
Quote from: "Duke"
Is it true that if you were going from Earth to space with the speed of light for several seconds and then go back on Earth you would see that several days have passed?

Yes. This is demostrated in the twins paradox. One twin stays on earth while the other travels in a spaceship that goes almost the speed of light. The space-travelling twin returns after a few years to find that his twin that stayed on earth is now older then him. Time slows as you near the speed of light. This also means to go faster then the speed of light, is to go back in time. As the ryhme goes:
There once was a lady in white,
Who could travel much faster then light.
She departed one day, in a relative way,
And arrived on the previous night.

Clocks that are onboard sattilites and the space shuttle have to be adjusted after they reach orbit also because they slow a bit as they launch into space because of the speeds involved. Ones that are not adjusted are noticably behind sister clocks when they return to earth.

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#### troubadour

• 551
##### Faster than time
« Reply #3 on: July 01, 2006, 12:53:19 PM »
what is even cooler is that if you could develop a probe, with very very very good optics, that could go beyond the speed of light. you could go let's say, 2100 light years away, turn around and look back, and see Caesar fighting the german barbarians on earth. The light from 2100 years ago is just reaching objects that are 2100 light years away.

#### James

• Flat Earther
• The Elder Ones
• 5613
##### Faster than time
« Reply #4 on: July 01, 2006, 01:05:12 PM »
Quote from: "troubadour"
what is even cooler is that if you could develop a probe, with very very very good optics, that could go beyond the speed of light. you could go let's say, 2100 light years away, turn around and look back, and see Caesar fighting the german barbarians on earth. The light from 2100 years ago is just reaching objects that are 2100 light years away.

optics rely on light. I don't see how you could "see" anything without light.
"For your own sake, as well as for that of our beloved country, be bold and firm against error and evil of every kind." - David Wardlaw Scott, Terra Firma 1901

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#### troubadour

• 551
##### Faster than time
« Reply #5 on: July 01, 2006, 01:11:38 PM »
I can explain this better. If you are in a car going 55mph due north, you have a velocity that is 55mph north. if you change your direction and go 50mph north and 5mph east, you are still going 55mph, but you are only going 50mph north and now, 5mph east.

Now we will come back to why I told you this. Common experience tells us that if we are in a car travelling 80 mph, then something that is travelling 100mph will only look as if travelling 20 mph to us. If we were moving 80mph in the opposite direction as we passed it, it would look as if travelling 180mph to us. We are all aware that light travels 300,000Km/s. What if we had a spaceship that could travel 250,000Km/s and we raced a light beam, what would we see? It turns out, no matter what, light always apppears to travel at 300,000km/s, even if we are moving at 299,999km/s, it would still appear to us to be racing off at 300,000km/s. It appears no slower, or faster. This has been confirmed time and time again in experiment and observation. Why? Einstein gave his reasoning for this in his theory of special relativity. Each observer has his own clock and yardstick. Each observer is just as correct as the other. The person that is stationary will measure light moving at 300,000km/s, and the person moving at 250,000km/s will also see the light as moving 300,000km/s relative to him because his yardstick will be different then the stationary observer because of his velocity. It turns out that the speed of light is one of the few constants in the universe that all can agree too. It is also the "speed-limit" of which we can travel though spacetime.

But wait, why does time slow for those that are moving faster through spacetime? Read again what I wrote at the beginning. Then look out the window at a parked car. Ignore the rotation and revolutions of the earth or sun and spinning of the galaxy, imagine it is perfectly still. It is moving through time at light speed, the maximum speed you can move through space is also the maximum you can move through time. Imagine that car goes and now moves 100kph down the road. It is now going 100kph through space, and 299,900kph through time. As you increase your velocity through space, you decrease your velocity through time. Exactly the same as if you were travelling at a constant speed in a car north, and you changed your velocity to the east a bit. you would not be travelling as fast to the north, and you would be travelling to the east more now, but you would still be going at the same velocity overall.

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#### troubadour

• 551
##### Faster than time
« Reply #6 on: July 01, 2006, 01:15:07 PM »
Quote from: "Dogplatter"
Quote from: "troubadour"
what is even cooler is that if you could develop a probe, with very very very good optics, that could go beyond the speed of light. you could go let's say, 2100 light years away, turn around and look back, and see Caesar fighting the german barbarians on earth. The light from 2100 years ago is just reaching objects that are 2100 light years away.

optics rely on light. I don't see how you could "see" anything without light.

nobody said anything about not having light.

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#### Knight

• 875
##### Faster than time
« Reply #7 on: July 01, 2006, 06:11:50 PM »
Quote from: "troubadour"
Yes. This is demostrated in the twins paradox. One twin stays on earth while the other travels in a spaceship that goes almost the speed of light. The space-travelling twin returns after a few years to find that his twin that stayed on earth is now older then him. Time slows as you near the speed of light. This also means to go faster then the speed of light, is to go back in time

I don't think it's demonstrated in the twins paradox, because we have no proof of the "twins paradox" ever having been carried out in experimentation.
ooyakasha!

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#### troubadour

• 551
##### Faster than time
« Reply #8 on: July 01, 2006, 06:35:44 PM »
Quote from: "Knight"
Quote from: "troubadour"
Yes. This is demostrated in the twins paradox. One twin stays on earth while the other travels in a spaceship that goes almost the speed of light. The space-travelling twin returns after a few years to find that his twin that stayed on earth is now older then him. Time slows as you near the speed of light. This also means to go faster then the speed of light, is to go back in time

I don't think it's demonstrated in the twins paradox, because we have no proof of the "twins paradox" ever having been carried out in experimentation.

yes we do. Cesium clocks have be syncronized and then one stays on earth while the other went into space on a rocket and then returned. We find that on the one that went into space, less time had passed, to the order of excatly as what Einstein predicted.

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#### Knight

• 875
##### Faster than time
« Reply #9 on: July 01, 2006, 06:58:31 PM »
Quote from: "troubadour"
yes we do. Cesium clocks have be syncronized and then one stays on earth while the other went into space on a rocket and then returned. We find that on the one that went into space, less time had passed, to the order of excatly as what Einstein predicted.

Yes, i'm aware that this has been tested--although I was under the impression that one was stationary (relative to earth) and the other was on a jet.  Anyway, this is the same idea as the "twin paradox"--only without the twins (unless you mean twin clocks) and without the "almost speed of light" spaceship.

Quote from: "troubadour"
One twin stays on earth while the other travels in a spaceship that goes almost the speed of light
ooyakasha!

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#### troubadour

• 551
##### Faster than time
« Reply #10 on: July 01, 2006, 09:02:41 PM »
Quote from: "Knight"
Quote from: "troubadour"
yes we do. Cesium clocks have be syncronized and then one stays on earth while the other went into space on a rocket and then returned. We find that on the one that went into space, less time had passed, to the order of excatly as what Einstein predicted.

Yes, i'm aware that this has been tested--although I was under the impression that one was stationary (relative to earth) and the other was on a jet.  Anyway, this is the same idea as the "twin paradox"--only without the twins (unless you mean twin clocks) and without the "almost speed of light" spaceship.

Quote from: "troubadour"
One twin stays on earth while the other travels in a spaceship that goes almost the speed of light

Then you would agree that if the velocity of the moving clock was further increased, time would pass slower and slower for it?

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#### Knight

• 875
##### Faster than time
« Reply #11 on: July 02, 2006, 11:01:08 AM »
Quote
Then you would agree that if the velocity of the moving clock was further increased, time would pass slower and slower for it?

Relative to earth, yes.  But consider a different situation where the two clocks are in black space (with no stars, planets, etc. visible).  As long as one of them is moving, each clock would be moving slower than the other one because they wouldn't know which one was moving and which one was stationary (or if both were moving).  This whole post was confusing, so correct me if I'm wrong.
ooyakasha!

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#### troubadour

• 551
##### Faster than time
« Reply #12 on: July 02, 2006, 11:41:54 AM »
Quote from: "Knight"
Quote
Then you would agree that if the velocity of the moving clock was further increased, time would pass slower and slower for it?

Relative to earth, yes.  But consider a different situation where the two clocks are in black space (with no stars, planets, etc. visible).  As long as one of them is moving, each clock would be moving slower than the other one because they wouldn't know which one was moving and which one was stationary (or if both were moving).  This whole post was confusing, so correct me if I'm wrong.

Relative to each other, the other one looks like it is moving. But relative to Spacetime, only one would be moving, and for this one time would pass slower. Both answers are correct.

People forget there is no absolute space, or absolute time, but there is absolute spacetime.

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#### DrQuak

• 256
##### Faster than time
« Reply #13 on: July 03, 2006, 05:39:20 AM »
Relativity is confusing, not this post. in fact many people have explained relativity about as well as it can be.

Unless you are doing University Physics or Astronomy do not try and think about relativity because you have no need for it.... i do University Physics and i try not to think about it ;-)

But yes they have increased the speed of a radioactive element to that of near the speed of light and it has decayed as predicted by Einstein. (ie it's decay rate was higher than it would have been if left still because it has experienced less time). The faster you got, the heavier things get too, as well as longer.

#### TheEngineer

• Planar Moderator
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• GPS does not require satellites.
##### Faster than time
« Reply #14 on: July 03, 2006, 11:07:10 AM »
Quote from: "DrQuak"

But yes they have increased the speed of a radioactive element to that of near the speed of light and it has decayed as predicted by Einstein. (ie it's decay rate was higher than it would have been if left still because it has experienced less time). The faster you got, the heavier things get too, as well as longer.

The experiment is normally carried out using muons - particles that are identical to electrons except they are about 200 times heavier - but last only about two millionths of a second- at which point they explode into electrons and neutrinos.
They get a muon going in an accelerator up to about 99.5% the speed of light.  At this speed, it's life is increased by a factor of ten.  This is due to the slowing of time for the muon.  As far as it can tell, it was only in the accelerator for 2 millionths of a second before it exploded, but in the rest frame of reference, it lasted 10 times as long.
I suggest that anyone who is interested in relativity, quantum mechanics or string theory read Brian Green's book The Elegant Universe.  It has great explanations for these things and they are presented in an understandable way.

"I haven't been wrong since 1961, when I thought I made a mistake."
-- Bob Hudson

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#### Erasmus

• The Elder Ones
• 4242
##### Faster than time
« Reply #15 on: July 03, 2006, 12:06:13 PM »
Quote from: "troubadour"
But relative to Spacetime, only one would be moving,

This seems to contradict your existing understanding of objects moving in spacetime, since you realize that all objects move at the speed of light, but merely in different directions.

Every observer defines his own spacetime coordinate system, with time as his proper time (the time on his clock).  No observer is preferred; there is no preferred coordinate system in spacetime.  Thus it's meaningless to say that one observer is moving "only along the time axis" and others are not.

Quote
People forget there is no absolute space, or absolute time, but there is absolute spacetime.

It's absolute only in the sense that the metric is absolute: the spacetime interval between two events is not dependent on the observer's motion.  It's not absolute in the sense that some world lines are "orthogonal to space" and others are not.
Why did the chicken cross the Möbius strip?

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#### Erasmus

• The Elder Ones
• 4242
##### Faster than time
« Reply #16 on: July 03, 2006, 12:12:24 PM »
Quote from: "DrQuak"
But yes they have increased the speed of a radioactive element to that of near the speed of light and it has decayed as predicted by Einstein. (ie it's decay rate was higher than it would have been if left still because it has experienced less time). The faster you got, the heavier things get too, as well as longer.

This seems.... mostly backwards.

If the element experienced less time, it should decay less.  If its half-life is, say, one minute, and it only experienced thirty seconds of proper time, then it would only have decayed to 1/sqrt(2) of its starting mass.  I.e., its recay rate is lower if it is in a moving reference frame, not higher.

As for length -- objects are shorter, not longer, in moving reference frames.
Why did the chicken cross the Möbius strip?

#### TheEngineer

• Planar Moderator
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• GPS does not require satellites.
##### Faster than time
« Reply #17 on: July 03, 2006, 12:16:12 PM »
Quote from: "Erasmus"
Quote from: "DrQuak"
But yes they have increased the speed of a radioactive element to that of near the speed of light and it has decayed as predicted by Einstein. (ie it's decay rate was higher than it would have been if left still because it has experienced less time). The faster you got, the heavier things get too, as well as longer.

This seems.... mostly backwards.

If the element experienced less time, it should decay less.  If its half-life is, say, one minute, and it only experienced thirty seconds of proper time, then it would only have decayed to 1/sqrt(2) of its starting mass.  I.e., its recay rate is lower if it is in a moving reference frame, not higher.

As for length -- objects are shorter, not longer, in moving reference frames.

I noticed this too, but I gave him the benefit of the doubt and assumed it was a typo.

"I haven't been wrong since 1961, when I thought I made a mistake."
-- Bob Hudson

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#### troubadour

• 551
##### Faster than time
« Reply #18 on: July 03, 2006, 12:35:48 PM »
Quote from: "Erasmus"
Quote from: "troubadour"
But relative to Spacetime, only one would be moving,

This seems to contradict your existing understanding of objects moving in spacetime, since you realize that all objects move at the speed of light, but merely in different directions.

Every observer defines his own spacetime coordinate system, with time as his proper time (the time on his clock).  No observer is preferred; there is no preferred coordinate system in spacetime.  Thus it's meaningless to say that one observer is moving "only along the time axis" and others are not.

Quote
People forget there is no absolute space, or absolute time, but there is absolute spacetime.

It's absolute only in the sense that the metric is absolute: the spacetime interval between two events is not dependent on the observer's motion.  It's not absolute in the sense that some world lines are "orthogonal to space" and others are not.

erasmus, we can debate about ways of measuring spacetime till the cows come home. it doesn't matter if you use our current time model or some other one, kilometers or miles, one coordinate system or the other, that's not the point of the post I made. I was simply stating that there is an absolute spacetime against which an object can be moving relative to even with no other points of reference. Of course with no other objects, one could not measure the change in time with the object's velocity, nor would it notice a difference in it's own time as it would not have anything else to be aging slower then, so maybe i have nulled my own example. but the idea of absolute spacetime remains the same.

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#### Erasmus

• The Elder Ones
• 4242
##### Faster than time
« Reply #19 on: July 03, 2006, 12:47:29 PM »
Quote from: "troubadour"
there is an absolute spacetime against which an object can be moving relative to even with no other points of reference.

Maybe I just don't know what you mean by this.

Mostly it's the "relative to spacetime, only one would be moving" bit that I disagree with.  Firstly, You don't really move through spacetime.  You occupy a line parametrized by a quantity called "proper time".  You're not "at one point" at some time and then "at some other point" later in time -- time is included in the geometry.  Secondly, to the extent that it's meaningful to talk about objects moving in spacetime -- i.e. you're talking about world lines -- there are no preferred world lines.
Why did the chicken cross the Möbius strip?

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#### DrQuak

• 256
##### Faster than time
« Reply #20 on: July 03, 2006, 04:50:02 PM »
i meant it would have experienced less time, therefore there would be a higher decay rate.... as in there are still more of them around to decay.

more counts per second that there would have been if it were experiencing everything normally....

#### TheEngineer

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• GPS does not require satellites.
##### Faster than time
« Reply #21 on: July 03, 2006, 11:24:18 PM »
Quote from: "DrQuak"
i meant it would have experienced less time, therefore there would be a higher decay rate.... as in there are still more of them around to decay.

more counts per second that there would have been if it were experiencing everything normally....

I'm going to stick with muons since the experiments have actually been done.

As stated before, a muon at rest will decay in 2 millionths of a second.  As an object speeds up, time slows down for it and, as Erasmus pointed out, it will become shorter.  To the muon in the accelerator, it is not moving, but the accelerator around it is.  Therefore, to it's internal clock, it is still at rest and after 2 millionths of a second, POP!  Now to the scientists, the muon is traveling at 99.5% the speed of light, and two hundred thoundths of a second passed before the muon popped into electrons and neutrinos.  At relativistic speeds, time slows down for the object in motion.

"I haven't been wrong since 1961, when I thought I made a mistake."
-- Bob Hudson

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#### Erasmus

• The Elder Ones
• 4242
##### Faster than time
« Reply #22 on: July 04, 2006, 12:48:16 AM »
Quote from: "DrQuak"
i meant it would have experienced less time, therefore there would be a higher decay rate.... as in there are still more of them around to decay.

That.... either doesn't make sense, or involves the simultaneous acceptance of two mutually exclusive concepts, or both, or something.

As far as the element is concerned, its decay rate is constant.  Now imagine the element carrying a clock with it.  It can measure this (constant) decay rate and will get whatever it's supposed to get.  Maybe in the first minute it loses half its mass.  We in the lab watch this thing move past very quickly, but we still see that in its minute the element loses half its mass.  However, its minute is longer than one of our minutes, so in one of our minutes the element loses less than half its mass.

Thus the decay rate of a moving sample is less than that of a sample at rest.
Why did the chicken cross the Möbius strip?

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#### DrQuak

• 256
##### Faster than time
« Reply #23 on: July 04, 2006, 05:39:27 AM »
sorry your right.... was quoting the wrong property.... this is what i get for going on forums after midnight.

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#### troubadour

• 551
##### Faster than time
« Reply #24 on: July 04, 2006, 06:49:53 AM »
Quote from: "Erasmus"
Quote from: "troubadour"
there is an absolute spacetime against which an object can be moving relative to even with no other points of reference.

Maybe I just don't know what you mean by this.

Mostly it's the "relative to spacetime, only one would be moving" bit that I disagree with.  Firstly, You don't really move through spacetime.  You occupy a line parametrized by a quantity called "proper time".  You're not "at one point" at some time and then "at some other point" later in time -- time is included in the geometry.  Secondly, to the extent that it's meaningful to talk about objects moving in spacetime -- i.e. you're talking about world lines -- there are no preferred world lines.

I've read a many book and never heard of "proper time".

#### TheEngineer

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##### Faster than time
« Reply #25 on: July 04, 2006, 09:37:10 AM »
Quote from: "troubadour"

I've read a many book and never heard of "proper time".

Proper time is time measured by the clock of an observer traveling through spacetime.

"I haven't been wrong since 1961, when I thought I made a mistake."
-- Bob Hudson