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Posted by: SCARFACE71795
If we know all this -blam!- about space.
Remind me why we aren't fully exploring space
Because it's costly and has no sure economic benefits. Rockets are expensive, and our rocket building technology hasn't improved much since the 60's; actually, as it happens, many of the base models of rockets still in use today were designed in the 1950's and 60's, such as the Russian Soyuz rocket.
The problem is, you need something with a very high thrust-to-weight ratio to get a craft into orbital and superorbitar trajectories, and it must continue to work even in the upper atmosphere. This requires rocketry under our current technology, and that's expensive.
And yeah, the main thing is, not much immediately visible economic benefit. They fund as much space research as they see profitable.
Can someone confirm/deny/explain this:
If one source sends light in one direction, and another source sends light from the opposite direction, if you were observing from within the first light, would the incoming light from the opposite end appear to be moving at lightspeed x 2?
It probably makes no sense, but theoretically, would it work?
You can't really "observe" from the first light, since time wouldn't pass for a light-speed reference frame relative to the rest of the universe at all.
In any case, regardless of what normal reference frame you're observing from, the observed velocity of the light in any localized situation is going to be c (as long as the light is propogating through a vacuum; some media can slow light waves down).
Let's look at another situation, ditching the idea of things moving "at c". Suppose in a given reference frame, two objects are moving at a very high fraction of c, and let's call their speed v. Then, in the reference frame of one of the colliding objects, the other object will be headed its way at a speed greater than v, but lower than c.
Velocities according to relativity are not directly additive.
P.S. This isn't an info thread, this is people trying to find out if Slipspace would cause time distortion/travel like FTL within this universe or if because of its seperate universe nature would have no such distortion effects. And believe it or not, most of it is. Yes, physics are annoying and complex.
It's actually not. I've explained time and time again that, if SR holds in real space, the actual distortion effects on the craft itself are irrelevant in the causality-breaking argument. If all you know is that at t=0, the craft is at Earth, and at t=1 in Earth's reference frame the craft is at Alpha Centauri, then it is possible to find a reference frame (pretty easy to do in this case, just take v=.99c and you're probably good) such that the craft arrived at Alpha Centauri prior to taking off from Earth. What the craft may or may not have done in the interim is 100% completely irrelevant. It doesn't matter if the craft itself suffers from spacetime distortion or not because what the craft experiences in irrelevant in the argument, and the only thing I'm taking into account is what Earth's reference frame sees and what some reference frame with a high relative speed to that frame sees.
We might as well not go on continuing this argument though, since we have completely irreconcileable zero points. I'm trusting the assumption of modern physics that SR holds in local space as long as you don't take extreme gravitational effects into account (at which point GR must be considered), and you're assuming it just plain doesn't.
Which is why I'm still concluding that the Haloverse effectively ditches modern physics, like most sci-fi universes.
[Edited on 12.09.2010 12:03 PM PST]