quote:
traveling near or at the speed of light is not a possibility. as you approach the speed of light, your mass increases, necessitating more and more energy to accelerate you further. at the speed of light, your theoretical mass is infinity and impossible to accelerate. even at speeds near the speed of light that might induce time dilation, the amount of energy needed is impractical and beyond our current technology.

I think I understand this because of the equation, but what about it being done in the vacuum of space, where a ship would not be slowed down and any speed attained would be maintained and added to (using something like a pulse jet)? I don't believe I've heard this limitation discussed in Through the Wormhole, and I gotta tell you, I'm a little disappointed in Morgan for withholding this potential roadblock from me.

This post was edited on 2/11/14 at 5:20 pm

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Posted by Spaulding Smails

Milano’s Bar

Member since Jun 2012

18805 posts

Posted on 2/11/14 at 5:44 pm to link

I'll post some when I get back home shortly

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Posted by link

Member since Feb 2009

19944 posts

Posted on 2/11/14 at 6:09 pm to Chucktown_Badger

quote:
I think I understand this because of the equation

it's not the e=mc2 equation. there's one that relates mass with the speed of light and velocity.

quote:
but what about it being done in the vacuum of space, where a ship would not be slowed down and any speed attained would be maintained and added to

yes, that's the scenario. just budging that speed up from .9 to .99 to .999 the speed of light takes monumental amounts of energy.

that limitation is one of the most basic principles of special relativity. think of all the money spent on the large hadron collider, and they use it to accelerate particles near the speed of light. just tiny particles of microscopic mass can't accelerate to the speed of light, let alone you in a spaceship.

my understanding is that time travel to the past is impossible, but traveling at/near the speed of light would basically equal future time travel. your time would pass very slowly, and earth's time would remain the same. 90 percent the speed of light is a magic number that doubles mass and halves time. if you got into your impossible rocketship and traveled 0.9 the speed of light for 10 years and returned, 20 years would have passed on earth. the faster you go, the more time slows down for you. so if you could travel at some high percentage of the speed of light, you could return in minutes while 100s of years have passed.

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Posted by TigerstuckinMS

Member since Nov 2005

33687 posts

Posted on 2/11/14 at 6:11 pm to Chucktown_Badger

quote:
traveling near or at the speed of light is not a possibility. as you approach the speed of light, your mass increases, necessitating more and more energy to accelerate you further. at the speed of light, your theoretical mass is infinity and impossible to accelerate. even at speeds near the speed of light that might induce time dilation, the amount of energy needed is impractical and beyond our current technology.

I think I understand this because of the equation, but what about it being done in the vacuum of space, where a ship would not be slowed down and any speed attained would be maintained and added to (using something like a pulse jet)? I don't believe I've heard this limitation discussed in Through the Wormhole, and I gotta tell you, I'm a little disappointed in Morgan for withholding this potential roadblock from me.

We'll conveniently ignore things like light that don't have mass for this discussion. It's going to be mathy enough.

E=m*c^2 is for a typical massy object at rest. A more general form includes another factor and is written E=y*m*c^2. y is the Lorentz factor and is equal to (1-v^2/c^2)^(1/2) where v is the objects velocity and c is still the speed of light. If you look at that Lorentz factor, and set v=0 (at rest), it reduces to 1, giving E=m*c^2. For low values of v seen by mere mortals, the Lorentz factor remains very close to 1, and the energy of the object essentially remains m*c^2. However, as v approaches c, the Lorentz factor becomes absolutely huge and because E=y*m*c^2, E becomes huge meaning that it takes exponentially more energy to make tiny increases in velocity near the speed of light. In fact, as v approaches c, the Lorentz factor approaches infinity, meaning that not only does the energy required grow very fast, but it takes an infinite amount of energy to accelerate that last tiny bit to reach the speed of light. The result is that thou shalt not travel at the speed of light.

It has nothing to do with what your ship is made of, what's pushing it, how it's being pushed, where it's being pushed. All that matters when trying to decide if you can reach light speed in simple relativity is one question: "Got mass?" If yes, the Lorentz factor means that even if your mass is tiny, the Lorentz factor drives E to infinity at velocities of c. So sorry.

A side effect of this is to look at how massive particle accelerators are. The LHC at CERN is tens of miles in diameter and that whole thing is built just to hurl tiny protons with almost no mass (compared to your average human) at each other. They're traveling very close to the speed of light, but they're not quite there. The Lorentz factor plays in and the machine has to be huge because even as tiny as protons are, it takes enormous amounts of energy to get them moving near c.

This post was edited on 2/11/14 at 6:29 pm

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