Do YOU believe in space aliens?

[Moonliner]

Originally Posted by surfinmuse

My thought is that a species (or planet, etc.) advanced enough for space travel of this magnitude to visit us, won't actually bother doing so. To loosely paraphrase a line from the new War of the Worlds movie, it's like a non-relationship between us humans and maggots: they do their thing, we do ours, we don't feel compelled to learn their language and communicate with them on their level.

My thought is that any alien visiting earth would be the interstellar equivalent of an Anthropologist. Grad students doing field studies and the like. As such they would certainly not hover over the white house and toot their horn. They would set up blinds and study us in our natural environment perhaps snatching a few specimens from deserted country roads or on Friday nights when they’ve had a bit too much space-juice turning the robo-surgeon loose to carve their initials on some local bovine livestock. As long as we don't have anything they need (like dilithium or Ben and Jerries) we should be left in peace to eventually blow ourselves up.

[Morrigoon]

Well, shoot. I can't find the link my friend once showed me about the time-space deal.

[Ghoulish Delight]

There's no supposedly about it. Time dilation (the slowing down of time for an object traveling at speed relative to an object at rest) is a central, and experimentally confirmed, component of Einstein's theory of relativity. It's what gives rise to the famed twim paradox.

It does pose some interesting issues. For example, let's assume that we satisfy ourselves with near-light speed travel. An astronaut could conceivably at those speeds reach another solar system 10 lightyears away (there are several that distance and closer). The good news: At those speeds, from the frame of reference of said astronaut, the distance will actually shrink (which is another way of expressing time dialation, I'm really still talking about the same effect), so it should take less than 10 years. The bad news...if it takes 8 years from the astronaut's perspective (16 total for the round trip), when he comes back, it will have been the full 20 years (okay, slightly longer if he's just under the speed of light).

As the distance increases, so does the gap. So there's a built in advantage and a built in disadvantage. The advantage is that the distances would be slightly more reachable than they'd appear from our perspective, allowing an astronaut to cross them in a fraction of the time that the measured distance might indicate. The disadvantage is that by the time the astronaut gets back, time on earth will have passed him by. He may have aged a couple years, while full generations have gone by at home.

[Tref]

Originally Posted by Moonliner

My thought is that any alien visiting earth would be the interstellar equivalent of an Anthropologist. Grad students doing field studies and the like. As such they would certainly not hover over the white house and toot their horn. They would set up blinds and study us in our natural environment perhaps snatching a few specimens from deserted country roads or on Friday nights when they’ve had a bit too much space-juice turning the robo-surgeon loose to carve their initials on some local bovine livestock. As long as we don't have anything they need (like dilithium or Ben and Jerries) we should be left in peace to eventually blow ourselves up.

Originally Posted by Goulish Delight

There's no supposedly about it. Time dilation (the slowing down of time for an object traveling at speed relative to an object at rest) is a central, and experimentally confirmed, component of Einstein's theory of relativity. It's what gives rise to the famed twim paradox.

It does pose some interesting issues. For example, let's assume that we satisfy ourselves with near-light speed travel. An astronaut could conceivably at those speeds reach another solar system 10 lightyears away (there are several that distance and closer). The good news: At those speeds, from the frame of reference of said astronaut, the distance will actually shrink (which is another way of expressing time dialation, I'm really still talking about the same effect), so it should take less than 10 years. The bad news...if it takes 8 years from the astronaut's perspective (16 total for the round trip), when he comes back, it will have been the full 20 years (okay, slightly longer if he's just under the speed of light).

As the distance increases, so does the gap. So there's a built in advantage and a built in disadvantage. The advantage is that the distances would be slightly more reachable than they'd appear from our perspective, allowing an astronaut to cross them in a fraction of the time that the measured distance might indicate. The disadvantage is that by the time the astronaut gets back, time on earth will have passed him by. He may have aged a couple years, while full generations have gone by at home.

Uh huh. My thoughts exactly. But here is the thing -- IT'S NEVER GOING TO HAPPEN!

[Ghoulish Delight]

For anyone who missed it the first time around, Einstein's Special Theory of Relativity 101

[scaeagles]

Originally Posted by innerSpaceman

the ability to travel from one inhabited planet to another is impossible only to those with hubris to think we now know it all.

I always thought hubris was possessed by those who think man has the capacity to know it all. But that's beside the point.

The laws of physics, as we understand them, change all the time, as do most of the things we think we know about the makeup of the universe. I am not a physicist or a scientist, so I really know very little about such things beyond the traditional and widely accepted theories. Einstein was wrong on more than one occassion.

[Ghoulish Delight]

By the way, credit where credit is due. It was not Einstein, but in fact Albert Michelson and E.W. Morley who, in the 1880s, discovered that light travels at the same speed, independent of the observer's frame of reference, the launching point for Einstein's Theory of Relativity.

My above example of the astronaut can't be fully explained by the basics of the Special Theory of Relativity, because the Special Theory assumes no acceleration (it also assumes that either observer in the system has the "right" to consider themselves at rest). The actual mechanics are greatly complicated by acceleration and require the far more complex General Theory of Relativity.

And if you're looking for real experimental confirmation of time dilation, look up the "Muon Experiment".

[innerSpaceman]

Originally Posted by Ghoulish Delight

And if you're looking for real experimental confirmation of time dilation, look up the "Muon Experiment".

Uh-oh, it sounds like the experiments where mad scientists cackle over the results, going "Muo ho heehee ho!"