His_Most_Royal_Highass_Donkey
12/31/10 01:36 PM
108.122.100.113
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To anyone that knows a lot about physics.
Relativity science and the speed of light.
Time is affected by speed so I have a question about that. The North Star is about 4 light years away from us. Now if a friend of mine got onto a theatrical ship that traveled at the speed of light and traveled to the North Star and back to whom would it seem like the trip took 8 years? Since here on earth we measured light relative to are speed of time I would say that it should be by my perspective that the trip took 8 years but my friend would have said that the trip took a lot less time. I don't know how long because I have no clue what the formula is.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
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Cray
12/31/10 09:21 PM
97.100.133.59
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Quote:
To anyone that knows a lot about physics.
Relativity science and the speed of light.
Time is affected by speed so I have a question about that. The North Star is about 4 light years away
Well, Polaris is 430 light-years away, but sticking to your 4-light year example...
Quote:
from us. Now if a friend of mine got onto a theatrical ship that traveled at the speed of light and traveled to the North Star and back to whom would it seem like the trip took 8 years? Since here on earth we measured light relative to are speed of time I would say that it should be by my perspective that the trip took 8 years but my friend would have said that the trip took a lot less time. I don't know how long because I have no clue what the formula is.
It would seem like 8 years to observers on Earth IF the ship made the 8-light year trip at 100% light speed. If the ship traveled at 50% of light-speed, then it would appear to take 16 years to observers on Earth. If the ship traveled at 10% of light-speed, then it would appear to take 80 years to observers on Earth. etc.
To the perspective of folks on the ship, the time passed does seem less. The equation isn't awful if you can handle some algebra, but it's not linear. The real "time dilation" effects don't kick in until you're traveling at a large percentage of light speed. It goes like this:
Te = T / square root of (1 - [v^2 / c^2])
Te is the time perceived on Earth
T is the time perceived elsewhere (easiest to set this at 1 year)
v is the speed of the ship (easiest to set this as a decimal fraction of light speed: 0 to .999999999)
c is the speed of light (easiest to set this 1, i.e., 100% of light-speed)
So to use that equation, you'd start out by squaring the velocity of the ship. If it's traveling at 50% of light-speed, then that's 0.5 x 0.5 = 0.25.
Then you'd divide that value by the square of light-speed, which is conveniently 1 if you're using v as a fraction of light speed. So, [0.5 x 0.5] / [1 x 1] = 0.25. (This is a lot easier than handling things in terms of mph or meters per second, which use much larger numbers. The results would be the same, though.)
Next, per the equation, subtract that number from 1. (1 - [0.5 x 0.5] / [1 x 1]) = 0.75.
Take the square root: square root (.75) = 0.867.
Finally, divide the shipboard time (easiest to say 1 year, 1 day, 1 whatever) by that number: 1 / 0.867 = 1.15.
So the time that passes on Earth is 1.155 times as long as on the ship at 50% of light-speed. In other words, the 16 years passing on Earth as a ship make a 8 light year round trip at 50% of light speed is 16 / 1.155 = 13.9 years on the ship.
If the ship moves at 90% of light-speed, the trip appears to take (8 / 0.9) = 8.89 years from Earth's perspective. However, from the ship's perspective, time passes noticeably more slowly. Te = 1 / sqrt(1 - [0.9^2 / 1^2]) = 2.29, so Earth time is 2.29 times as long as ship time. The 8.89 years on Earth only seems like (8.89 / 2.29) = 3.84 years to the ship's crew.
The effects become much more dramatic as you get closer and closer to light-speed:
http://en.wikipedia.org/wiki/File:Time_dilation.svg
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
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His_Most_Royal_Highass_Donkey
01/01/11 02:29 AM
68.26.145.145
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I stand corrected on the distance of Polaris. From a child I was told that the north star was the closest star and that it was 4 light years away.
I am in the proses of writing a scifi story and I want to have things some what scientifically correct. What I needed the info for was a ship is flying through a solar system close to the speed of light to prevent form being detected.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Cray
01/01/11 02:37 AM
97.100.133.59
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Quote:
I stand corrected on the distance of Polaris. From a child I was told that the north star was the closest star and that it was 4 light years away.
That's partly correct. The closest star is 4 light years away (4.3, if you're nitpicky), but it's in the constellation "the Southern Cross," and is known as Alpha Centauri (aka Rigel Kentaurus in BT).
http://en.wikipedia.org/wiki/Alpha_centauri
Quote:
I am in the proses of writing a scifi story and I want to have things some what scientifically correct. What I needed the info for was a ship is flying through a solar system close to the speed of light to prevent form being detected.
For that subject a good novel to pick up is "The Killing Star" by Charles R. Pellegrino and George Zebrowski. It's a hard science look at a near-light speed pass through our solar system by genocidal aliens. The science is excellent, the descriptions solid, and the book is terminally depressing. I only read it once because its discussion of a near-light speed attack on Earth was unnervingly convincing and depressing.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
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Frabby
01/01/11 05:43 AM
87.164.172.147
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Quote:
The closest star is 4 light years away (4.3, if you're nitpicky), but it's in the constellation "the Southern Cross," and is known as Alpha Centauri (aka Rigel Kentaurus in BT).
It's also known as Proxima Centauri (the closest Centauri star, whereas Alpha denotes the visually brightest - in this case they're the same). And I'm told it's actually a trinary star system.
</nitpick>
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Cray
01/01/11 11:08 AM
97.100.133.59
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Quote:
Quote:
The closest star is 4 light years away (4.3, if you're nitpicky), but it's in the constellation "the Southern Cross," and is known as Alpha Centauri (aka Rigel Kentaurus in BT).
It's also known as Proxima Centauri (the closest Centauri star, whereas Alpha denotes the visually brightest - in this case they're the same). And I'm told it's actually a trinary star system.
</nitpick>
Yes, Proxima Centauri, aka Alpha Centauri-C, is the third stellar component of the Alpha Centauri system (probably, astronomers are arguing about how bound it is to the gravity of Alpha Centauri-A and -B). However, as part of the Alpha Centauri system (specifically, Alpha Centauri-C), it was easier just to call it Alpha Centauri and cover all the contingencies in debates like this. 
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
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