Author Topic: space travel  (Read 892 times)

The Good Reverend Roger

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Re: space travel
« Reply #15 on: July 19, 2012, 03:35:41 pm »
The Universe inflated past the speed of light when it had just been created.

And just what's THAT all about, Mr Secular Humanist?

Oh, I'm pretty sure that God does exist and he's playing tricks on us.  :lulz:

More like CHEATING.
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Nepos twiddletonis

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Re: space travel
« Reply #16 on: July 19, 2012, 03:37:44 pm »
While thats fair you also have time dilation as a problem. It would bungle the calculations more. Maybe no i dont know but a lot of weird crap will have to be taken care of.
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Nepos twiddletonis

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Re: space travel
« Reply #17 on: July 19, 2012, 03:40:20 pm »
Lol rog- gods using a game genie
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Golden Applesauce

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Re: space travel
« Reply #18 on: July 20, 2012, 01:41:22 am »
Also, they say you can't travel at the speed of light, but I say that's bullshit if you cheat. Just find an object that's moving toward you at half the speed of light, and you travel toward that object at the other half of the speed of light.

Most celestial objects don't travel at relativistic speeds. This star system, for example, travels approximately 1 AU in orbit around the galaxy per week. Now, that's pretty fucking fast by our standards. But not even a decent fraction of the speed of light, since 1 AU is 8 light minutes. Celestial motion isn't going to help much with interstellar travel. If anything it's going to fuck things up. For example, we see Alpha Centauri from where it was 4 years ago. Imagine heading to a star system 100 light years away. You'd miss it completely unless you were constantly adjusting. You're completely fucked if you're going past the speed of light. It would be like getting lost down an endless array of side streets.

More evidence that physicists are just angry that they never got invited to all the cool parties, and they're getting us all back by declaring all of Humanity's hopes and dreams "impossible."

Hey, I didn't say impossible, just really fucking difficult.

Also, if you want to cheat with light speed, you have to make the space around you move faster that light. We don't know if that's possible but it can't be ruled out yet. The Universe inflated past the speed of light when it had just been created.

The universe is still inflating at over the speed of light, if you count the parts of the universe that are far enough away. Hubble's Law states that the observed velocity at which an object moves away from you due to universe expansion is proportional to the distance between you and it. The space outside the Hubble Volume is expanding at FTL speeds.
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Nepos twiddletonis

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Re: space travel
« Reply #19 on: July 20, 2012, 01:49:27 am »
Yep. Game genie.
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Golden Applesauce

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Re: space travel
« Reply #20 on: July 20, 2012, 01:55:37 am »
Also, they say you can't travel at the speed of light, but I say that's bullshit if you cheat. Just find an object that's moving toward you at half the speed of light, and you travel toward that object at the other half of the speed of light.

Once you find the object traveling towards you at .5c, you're already traveling towards it at .5c by symmetry.
The result is that you're traveling at .5c, relative to that object - no speed limits broken.

You can travel faster than the local speed of light if you go somewhere where light travels slower (like underwater - light travels at .75c there). c is just the speed at which light travels under ideal conditions (a perfect vacuum); actual light will go slower if there's matter and electric fields everywhere. See Cherenkov radiation for what happens when you do.
« Last Edit: July 20, 2012, 02:04:11 am by Golden Applesauce »
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Golden Applesauce

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Re: space travel
« Reply #21 on: July 20, 2012, 02:08:56 am »
I KNOW NOTHING ABOUT PHYSICS AND RELATIVITY. This question will probably sound incredibly ignorant to someone who does, but I'm asking it anyway.

SO... Say you want to travel from Earth to Alpha Centauri (or wherever). It's hard to do that because it's "so far away" etc., and we can't travel "fast enough" to get there within anything approaching even a major epoch of Human history.

That is a simplistic explanation, of course, because it isn't like Earth is some stationary object -- it's hurtling through space at fuck knows how many miles per hour, and so is your destination.

So my question is:
If a spacecraft in Earth's orbit, it is still hurtling through space at roughly the same speed as the Earth due to the fact that it shares Earth's interstellar momentum (like throwing a baseball out of a moving car's window, minus wind resistance). Isn't that momentum already carrying an ungodly amount of kinetic energy, and can't we somehow "brake" the spacecraft's speed relative to Earth, causing it to speed away toward some other Destination in space which is hurtling toward it at the same speed Earth is hurtling away?

State how this question misses a bunch of obvious and elementary science in three sentences or more.

It sounds like you're trying to describe the gravitional slingshot maneuver, which works but would only convert your relative velocity towards Earth into a velocity of the same speed but away from Earth; you don't get any bonus points for being co-moving with it.

But basically what TGRR said - if you have X kinetic energy, it takes X energy to "brake" and another X to accelerate to the same speed in the opposite direction. The only advantage of the gravitational slingshot is that you get that 2X energy out of a planet or something that can spare a few megajoules.
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