First Habitable Planet Confirmed.

You have it right, but your frame of reference is inverted.

They're the ones traveling at the speed of light, so they're the ones that get there in 20 years their time. Much longer passes here on earth.

This is obvious if you think about it conceptually. Let's say your version was true, and they got there in 20 years OUR time.

How would we even know? It's 20 light years away. The "event" of their landing would still have to travel back for us to know about it. So from our frame of reference, it still hasn't happened, and has to take 20 years + some amount. There is no universal clock.

That's how Stephen Hawking's time travel idea works. You basically put yourself in orbit about a black hole, traveling very fast in very high gravity, and your time slows down. The rest of the universe, relative to you, speed up. When you leave the black hole orbit, you have effectively "traveled into the future" because your clock progressed normally, and everything else sped up around you.

It's conceptually the same for a high-speed trip to another star.

Like all black men eat watermelon and chicken, and are incapable of getting a job, right?

Stereotypical racism is fun.

Humans naturally spread and conquer though, it's more a species flaw than race I think?

Fixed

All organic life forms naturally spread and conquer. There's no reason to separate by race or even assume it would be different for another species.

Hence Hawking's famous recent warning that we probably shouldn't go looking for extraterrestrials with open arms.

Subspace frequencies. Gosh Jaerik, haven't you watched Star Trek™? :D

Touche sir, although don't you think we're a bit worse than others?

I'm not so sure about this (going only by the posts here). A light year is a static measure of distance. A light year is the distance light travels in one earth year which is approximately 6 trillion miles.

It isn't a measurement of speed or time which can be distorted by traveling at high speeds.

If an object is traveling near the speed of light, at a 20 light year distance, it would take them a little over 20 years (earth time) to travel that distance.

Alternatively you can look at the problem this way.

light travels at approximately 186,282 miles per second.

A light year is approximately 5,878,625,373,183 miles.

Assuming close to the speed of light means something like 185,000 miles per second:

185,000(miles/s)*60(s/m)*60(m/h)24(h/d)365(d/y) = 5,834,160,000,000 miles per year. this number is pretty close to the distance in a light year. If you divide the distance in a light year by the speed of near light travel you get 1.0076 years. Multiply that by 20 and you get 20.152 years.

As far as I know these measurements of time in calculating light years and speed of light are based off the relative time passage as it passes on earth. So it would take a little over 20 earth years moving at near speed of light to travel 20 light years. Time relative to the people traveling at 185,000 miles per second would be shorter.

I'd lay that on the fact we can easily adjust to different environments, so there's practically no where we can't go and stay.

YEEEEEES

WE'RE ONE STEP CLOSER TO ENDER'S GAME

YEAAAAAAAAAAAAAAAAAA

Yeah, we might end up with this little conundrum on our hands...



I couldn't help myself.

/snicker

Not really.

Stop being a racist schmuck.

You're being confused by arguing backwards from earth's frame of reference.

There is no universal clock. "Earth time" isn't even real, because we're moving at a pretty decent clip through space, and so under the effects of relativity already!

Remember: light speed is constant to you, no matter how fast you're moving. Light has no mass. It doesn't undergo its own time dilation. A "light year" is a light year no matter who's measuring it... for light.

It completely changes when you're talking about a physical object moving at light speed. Remember, it doesn't work like my water gun example. In order to preserve the speed of light relative to you, the laws of physics have to "give." Your time has to slow, meaning to you, time for everyone else speeds up.

Humans adapt well on this planet. On the surface.

If you can assume humans can live in the temperature range of roughly -20 - 45 C, which is a very generous temperature range, and between 7 and 8 Kpa you limit yourself to an incredibly small range in which humans can survive, ignoring all other factors that may inhibit human life, toxic elements and presence necessary compounds to sustain human life, predators, disease etc etc.

I have a headache from reading this thread! I wish I could understand this lol

Those standards are set relative to the passage of time on earth. If we are talking about the standard of a light year, a light year is defined as the the distance light travels in one earth year, relative to that year as observed from earth.

I don't intimately understand relativity, but I understand relativity enough to get your point. My point is that all those measurements and definitions are taken as standards based on earth's relative passage of time. So taking those numbers would yield a 20 year travel of that spaceship to an earth observer, and less (because as speed increases, the passage of time decreases) for someone who traveled on the spaceship.

If you didn't take some standard any measurement of time would be meaningless. When we say it takes 8 minutes for light to travel from the outer sun to the earth we say that it takes 8 minutes relative to earth time, not time relative to the speed of light, or speed near light.

EDIT: the disagreement comes from where we are setting our standard. I think the passage of time in calculating the distance in a light year refers to the earth observer, and you think the passage of time refers to the observer on the near light spacecraft. Wiki isn't entirely unambiguous about this point, it doesn't mention where the observer is.

Ahhh...I suppose we were going in completely different directions. I was just thinking in terms of human colonization.

I suppose you're right. I just think humans, as adaptable as we are, would be lacking some of the dietary benefits, climate consistency, etc... that we overlook and take for granted in our every-day lives on Earth.

Maybe I'm being a little cynical, but I just always think of these scenarios as a possible astro-Roanoke Island. LOL!

Thats why its more feasible to study the science of bending space and time so the point of origin and the point of destination meet. Thinking of interstellar travel like its traveling on a globe is ridiculous at best. Moreover, it has been theorized that this is what wormholes do.

There's no pressure in a vacuum, it's not like driving a car in a wind tunnel. But yes it would take a phenomenal amount of energy to bring something with mass up to near light speeds.

Ummm, you do know that black holes and wormholes are two completely different phenomenon. Plus, black holes devours all light and slows time and space down all around it. Black holes and wormholes are not mutually inclusive.

A wormhole is hypothetical, as are black holes. We can observe where we assume black holes are, but we can't observe on directly and we've never sent a probe or a person into one.

Edit granted we've never actually observed a worm hole, having them allows for all kinds of equations that wouldn't be able to be solved previously become solvable.

It can't be, otherwise a "light year" would be different when looking in the direction that earth is traveling, and away. A "light year" is not relative to our movement.

There is no need to "calibrate" a light year. Light is light. It is its own standard, and indeed, the only one. Its speed is absolute no matter what speed and direction our measly, corporeal forms are traveling. It takes light 8 minutes to reach Earth whether our planet was standing still or moving, because the internal timer would be stretched in either case to make it end up the same.

You were closer when you said that "any measure of time is meaningless." It is! That was Einstein's whole point. Time is relative.

There isn't even an agreeable "if observed from earth" time. If while typing this, I slowly rolled my chair backwards from my desk relative to you, our clocks just shifted. We no longer agree on the time. The difference is so microscopic relative to the speed of light, the effect is immeasurable, but it's there.

What I posted earlier was correct Jaerik. The closer the travelers get to the speed of light, the shorter the trip becomes to them, due to lorenz contraction. To an observer in the outside frame (not in the spaceship) the ship takes slightly more than 20 years to reach the destination. To those in the near-light speed spaceship, the entire universe appears to become contracted in the direction of the movement, while the ship itself appears to still be moving at near-light speed. Thus, the trip is shorter than 20 years, much shorter at near-light speed.