although, thats supposing that its due to a force of gravity at all...
]]>And darkmatter, for all intensive purposes, exists. It solves problems that we see with galaxy movements as well as problems within the Big Bang theory. If it didn't exist, we would have to throw all of Einstiens equations away. It has been indirectly detected in a number of ways.
However, in what form it exists, is still up to much debate.
To put it briefly, we have no knowledge, theoretically or otherwise, of the existance of particles with negative mass. Just a few physicists who got high and said, "You know, what if matter had negative mass?!?"
]]>No, antimatter has opposite electric charge. As far as I know, negative mass has not been confirmed anywhere in physics.
ah yeh, i was thinking of dark matter which as you say, hasnt been confirmed to exist
]]>Also, there is nothing to suggest that there are no particles that travel faster than the speed of light (tachyons). Relativity says if those particles exist, they cannot accelerate (slow down) to the speed of light.
Such particles must have negative mass to be compatible with relativistic equations. Not saying that it isn't possible, just that it makes no sense.
doesnt anti-matter, have negative mass?
]]>Also, there is nothing to suggest that there are no particles that travel faster than the speed of light (tachyons). Relativity says if those particles exist, they cannot accelerate (slow down) to the speed of light.
Such particles must have negative mass to be compatible with relativistic equations. Not saying that it isn't possible, just that it makes no sense.
]]>Yes, but you're assuming that light obeys the same laws of physics as everything else. According to the laws of physics, nothing can reach the speed of light, so light's broken that one already!
Someone correct me if I'm wrong, but I believe relativity implies that the speed of light is a barrier that cannot be crossed. Photons either travel at the speed of light, or their energy absorbed into matter. They have not broken the barrier.
Also, there is nothing to suggest that there are no particles that travel faster than the speed of light (tachyons). Relativity says if those particles exist, they cannot accelerate (slow down) to the speed of light.
]]>Doppler: If my hypothetical near-light-speed spacecraft sent an audio message back to earth, the signal would travel back to earth at the speed of light, but Earth would (eventually) hear my voice sounding v-e-r-y s-l-o-w, right?
well, im not so sure about the (eventually) part, but the being very elongated seems logical
but ofcourse, you could easily get around that, by just being stationary when sending data back or needing to receive it
]]>A theory I read in a book somewhere: Travelling just over the speed of light in space will lead to time slowing down in the shuttle itself. That would probably look and feel amazing - And probably scary...?
I think you mean just under. And this effect happens no matter what speed you are traveling. It just happens to a greater extent when you are traveling faster.
When you walk to your kitchen to get a sandwhich that is sitting on a table, you are moving in time slower than that sandwhich is. It isn't noticable, but it's happening.
]]>The other problem is that even with the high exhaust velocities, energy density is still an issue. You have to carry enough propellent and energy (nuclear is currently the best candidate; most long-range probes have been nuclear powered) to reach those high velocities.
This is why the energy balance is more interesting to me than the time dilation; it's what's holding us back in space.
]]>It doesn't seem like it should work, because usually momentum is mass x velocity, but then, it doesn't seem like anything to do with light should work really.
Well said. What we are looking at is a world we can't see, so it's only intuitive that everything is counter-intuitive.
I meant that the speed of sound is variable depending on who is observing it. If you are travelling away from the sound source, then the sound will be slower for you than for someone who is stationary.
Ah, ok. I thought you meant it was the source of the sound that was moving.
But the main point of the Doppler effect has nothing to do with velocity, but frequency instead. When you move away from the source, you will hear the sound at a lower pitch or see the light at a lower frequency.
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