Racecar on a Train

[jonesy]

for the purposes of a 40 second or 16 year test, how much drift between my space station and alpha centauri are we talking about? Is it adding 5 feet, 5 miles, 5 light years? For the purposes of a short term test, true motionlessness and non-significant drift are good enough.

That's not quite what I was talking about, but the universe is expanding at the speed of 74.2 kilometers/second/megaparsec (this is from 2009).

What is the ratio of time slow down to fraction of light speed?

Roughly, at .7c you are adding months to the time that the observer experiences versus what the traveller does during a few years of travel time. At .9c you are adding years. And after .999c it starts getting crazy.

 

[Bullgrit]

Roughly, at .7c you are adding months to the time that the observer experiences versus what the traveller does during a few years of travel time. At .9c you are adding years. And after .999c it starts getting crazy.

So it does get to the point that from the Traveler's point of view, he traveled a lightyear distance in less than a year of time? Maybe even to the point of instantaneous?

Starman: I laughed out loud at your xp awards above. I get the reference.

Bullgrit

 

[jonesy]

So it does get to the point that from the Traveler's point of view, he traveled a lightyear distance in less than a year of time? Maybe even to the point of instantaneous?

That close to 1c the distance you can travel increases almost at the same ratio as the difference in time experienced by the observer.

In other words, I have no idea how to calculate what you're asking.

 

[Janx]

That close to 1c the distance you can travel increases almost at the same ratio as the difference in time experienced by the observer.

In other words, I have no idea how to calculate what you're asking.

is it sufficient to say, that the super faster you go, the slower time goes in the spacecraft (clock and passenger).

Thus, the faster you get there, you will spend even less of your life on the trip

 

[Starman]

For those curious about time dilation, Wikipedia has a good page on it. I won't repost any of the formulas here in an effort to keep readership from declining further.

 

[Bullgrit]

Time dilation can arise from:

1. the relative velocity of motion between two observers

Wait a minute. Wait a minute. The relative velocity between the two observers? So if Traveler A is traveling at .5c "east" and Traveler B is traveling at .5c "west"... they will see each others time differently from each other *and* from how stationary Observer sees their time? Even though they are going the same speed, but in opposite directions. Will each see the other's clock stopped because their relative velocity is 1.0c?

I find these discussions on this kind of subject absolutely fascinating.

I just bought The Universe in a Nutshell, but I'm waiting to read it on my vacation in 2 weeks.

Bullgrit

 

[Relique du Madde]

Of course, if the racecar is a DeLorean then of course the situation changes completely.

The strange thing about DeLoreans is that you can never speed past 89 mph without accidently finding yourself at your destination extremely late or extremely early compared to the time it would take to arrive at the location in a Veyron.

 

[Pbartender]

Wait a minute. Wait a minute. The relative velocity between the two observers? So if Traveler A is traveling at .5c "east" and Traveler B is traveling at .5c "west"... they will see each others time differently from each other *and* from how stationary Observer sees their time?

Yes.

Even though they are going the same speed, but in opposite directions. Will each see the other's clock stopped because their relative velocity is 1.0c?

No, because they have mass, their relative velocity is not 1.0c, but (using GSHamster's equation above) 0.8c.

In the interest of saving people's sanity, spoilered mathematics:

[sblock]velocity = (u + v) / (1 + (uv/c²))

velocity = (0.5c + 0.5c) / (1 + ((0.5c * 0.5c)/c²))

velocity = 1.0c / (1 + (0.25c²/c²))

velocity = 1.0c / 1.25

velocity = 0.8c[/sblock]