Does time exist in space?

glen8 said:
I really don't get the whole light speed and time travel thing?

say you built a space ship which went 10 times the speed of light. You left earth on full throttle. You travelled at 10 times the speed of light for one week. You could be very far away from the earth, but you have aged a week, and so has everyone else on the earth.

You then travel back which again takes a week. You are two weeks older, but so is everyone else on the earth.

You have basically just travelled a very far distance and back again

where's time travel come into it? How can I travel a week into the future whilst staying put on the earth? (obviously im after the lotto results)
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Flubble said:
what's travelling at the speed of light got to do with ageing? surely moving at the speed of light for 1 earth year will age you by 1 year and age everyone else not moving by 1 year? :confused:
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Relativity. Basically, as you travel faster, time slows down. So if you were to hop on a ship doing nearly the speed of light (as travelling at, or faster than the speed of light is impossible for any object with mass), then after you had spent one week on the ship, the rest of the universe would have aged much more than one week.

http://en.wikipedia.org/wiki/Time_dilation#Relative_velocity_time_dilation
 
glen8 said:
time is a human concept, it's simply a measurement

we used the earth as a reference

so in answer to your question, let's say you jumped in a space ship and zoomed off to a distant planet 1,000,000,000,000 light years away

Time would exist, if you wanted it to. You would have to create the measurement based on the characteristics of the new planet you landed on. You could say a year would be the time the planet circled it's sun. The only issue is that planet could circle it's sun in the same amount of time our planet circled our sun 100 times.

so 100 years on earth, would be 1 year in your measurements. You could use a different reference, say the new planets moon. or you could use our existing measurements, but that would be silly if you were on the other side of the galaxy. It's like saying aliens use our measurement of time, which would be highly unlikely.

does that make sense?
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No.
 
For me the easiest way to understand relativity is to think of it as a number.

Say the combined total of speed and time can only be 100 (units don't matter).

If you are travelling very quickly, say at 90, then only 10 can be used for time.

However, on earth the speed might be low, say 5, so the time value will be 95, meaning time passes more quickly compared to the person travelling at 90.

That's a very simple way to look at it, and if I'm wrong I apologise, but for me it's much easier to understand if I use a number.
 
DAnDan said:
Relativity. Basically, as you travel faster, time slows down. So if you were to hop on a ship doing nearly the speed of light (as travelling at, or faster than the speed of light is impossible for any object with mass), then after you had spent one week on the ship, the rest of the universe would have aged much more than one week.

http://en.wikipedia.org/wiki/Time_dilation#Relative_velocity_time_dilation
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Gravitational time dilation is also interesting, like if you have a tall tower on earth with two clocks, one at the top and one at the bottom - the top one will be ticking slightly faster than the bottom one, because it's further away from the earth where the gravity is weaker. (they have this problem with GPS satellites, needing to be adjusted all the time)
 
Kronos said:
No.
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It makes complete sense. Earth only takes 24 hours to orbit the sun, but that's based on the physical properties of our earth and our sun. We define this as a day. Elsewhere, planets will take a different amount of time to orbit the sun (imagine you lived on Mars, for example), and therefore you'd define a day differently to on Earth.
 
dirtychinchilla said:
It makes complete sense. Earth only takes 24 hours to orbit the sun, but that's based on the physical properties of our earth and our sun. We define this as a day. Elsewhere, planets will take a different amount of time to orbit the sun (imagine you lived on Mars, for example), and therefore you'd define a day differently to on Earth.
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http://en.wikipedia.org/wiki/Earth's_orbit or a year ;)

http://www.polaris.iastate.edu/NorthStar/Unit3/unit3_sub1.htm a day
 
dirtychinchilla said:
It makes complete sense. Earth only takes 24 hours to orbit the sun, but that's based on the physical properties of our earth and our sun. We define this as a day. Elsewhere, planets will take a different amount of time to orbit the sun (imagine you lived on Mars, for example), and therefore you'd define a day differently to on Earth.
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What if you drop using days as a measurement of time, and used minutes, or seconds instead. What if you measured time by a metronome. If a process takes 100 ticks, it would take the same period of ticks, regardless of location / sped etc, as the ticking is a constant (like time). Ergo, I don't see how time can be experienced differently by the rotational speed of the planet you are on, as it is constant. If someone lived for 10,00,000 ticks on this planet, they would live for 10,000,000 ticks on a different planet, even if that planets spin on its rational axis was 4 x as quick?
 
snakefood said:
What if you drop using days as a measurement of time, and used minutes, or seconds instead. What if you measured time by a metronome. If a process takes 100 ticks, it would take the same period of ticks, regardless of location / sped etc, as the ticking is a constant (like time). Ergo, I don't see how time can be experienced differently by the rotational speed of the planet you are on, as it is constant. If someone lived for 10,00,000 ticks on this planet, they would live for 10,000,000 ticks on a different planet, even if that planets spin on its rational axis was 4 x as quick?
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Think about how the doppler effect works.

Now, using your metronome example, ticking at 1 hz:

If someone was moving alongside the metronome, the ticking would remain at 1hz, regardless of the speed, however, if the metronome moved past you, you would hear the ticking speed up as it approached, and slow down as it moved away.

Now that's on a low speed basis, so imagine how that would be amplified if moving at the speed of light...

It doesn't work in quite the same way, but might help you to visualise it.
 
If there was no time at all then nothing would ever change but people are right in saying that our second/minute/hour/day/month/year cycles would be meaningless anywhere except on Earth, you would use different cycles of time on other planets much like we have different time zones on Earth.
 
This is a good way of explaining relativity:

"Throwing a Ping-Pong ball down the aisle of a train.

As long as the speed and direction are constant, the Ping-Pong ball would behave exactly the same whether the train's creeping along at a snail's pace or barreling down the tracks. As long as the train isn't jerking around due to speed or directional changes, there's absolutely no difference inside the train car.

Outside the speeding train, however, it's a different story (or frame of reference).

To the individual aboard the speeding train -- let's say it's traveling at 100 miles per hour (161 kilometers per hour) -- the ball appears to move at regular speed. To the individual standing by the tracks, the ball (assuming he or she could see it) would appear to move with the speed of the train, plus the speed with which it was thrown."

If you observe the ball from outside the solar system, the ball is moving down the train, along the ground as the train is moving, it's also spinning in circles as the earth is rotating, and its also flying around the sun.

In other words, the ball that's observed just moving in a straight line on the train, is behaving very differently when observed from space.

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