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Thread: We are not alone . . .

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    Senior Member Rook's Avatar
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    Default We are not alone . . .

    Earth-size planets 'number 17 billion'

    Astronomers say that one in six stars hosts an Earth-sized planet in a close orbit - suggesting a total of 17 billion such planets in our galaxy.

    The result comes from an analysis of planet candidates gathered by Nasa's Kepler space observatory.
    17,000,000,000 Earth-sized planets . . . a fair few must have the right combination of factors which allow for life

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    Quote Originally Posted by Rook View Post
    17,000,000,000 Earth-sized planets . . . a fair few must have the right combination of factors which allow for life
    Indeed, and you should bear in mind that 17 billion is probably going to be a conservative estimate. And this is just in our own galaxy - there are another trillion or so galaxies in the small part of the Universe we are able to observe.

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    Super Moderator eatmywords's Avatar
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    Enough with the star-gazing, let's get to one these places! I want to see us go beyond our own solar system in my lifetime, and I want the pictures to prove it.
    Faced with certain disaster, defiance is the only answer.

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    Quote Originally Posted by eatmywords View Post
    Enough with the star-gazing, let's get to one these places! I want to see us go beyond our own solar system in my lifetime, and I want the pictures to prove it.
    Or perhaps they will get to us eatmy,. They could give you the ride you want, and send you back with the pictures.
    Last edited by Mack; 01-19-2013 at 08:08 PM.

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    Quote Originally Posted by eatmywords View Post
    Enough with the star-gazing, let's get to one these places! I want to see us go beyond our own solar system in my lifetime, and I want the pictures to prove it.
    I can't agree more, but I can't see it happening in the next century of so. With current chemical rocket technology, it would take 40,000 years to get to Alpha Centauri. Ion pulse drives or solar sails might shave the travel time down to a few centuries, but it is still too long. Of course, there is always the possibility that new technology - perhaps based on nuclear fusion - might become available. Here's hoping!

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    Senior Member Rook's Avatar
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    Personally, I just can't see inter-stellar travel ever being feasible - certainly not the sci-fi "FTL" drives which get you to the next solar system in a matter of hours. I know the "look-how-far-we've-progressed-in 100-years" argument, which implies that we'll have previously unimaginable tech in 100 years, but I think it's by no means a certainty. I think the best we'll manage, is a super fast engine which will get there in a dozen or so generations

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    Super Moderator eatmywords's Avatar
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    I think science needs to focus on light, on how it can travel such vast distances in short spaces of time. But what do I know.

    I did see a science programme on how they have managed to slow down light to the speed of a bicycle - by passing it through absolute zero hydrogen. Now, I'm sure that's all well and good, but do we really need light travelling at the speed of a bicycle?
    Faced with certain disaster, defiance is the only answer.

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    Senior Member Rook's Avatar
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    Quote Originally Posted by eatmywords View Post
    I think science needs to focus on light, on how it can travel such vast distances in short spaces of time. But what do I know.
    That's partly why I have my doubts about "FTL" drives. We know the reasons we can never travel at the speed of light (we have mass), and I can not see how we can ever overcome such a fundamental fact. We'd have to overcome some pretty powerful fundamental forces to become massless . . . Worm holes are a trick, and would be great if they worked, but again, I'm doubtful they'll be practical

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    Quote Originally Posted by Rook View Post
    That's partly why I have my doubts about "FTL" drives. We know the reasons we can never travel at the speed of light (we have mass), and I can not see how we can ever overcome such a fundamental fact. We'd have to overcome some pretty powerful fundamental forces to become massless . . . Worm holes are a trick, and would be great if they worked, but again, I'm doubtful they'll be practical
    Even massless particles are limited to the speed of light. To go faster than the speed of light, your mass, length and the time you elapse would have to become a complex number ... i.e. including square roots of minus one! Clearly a non-starter.

    Having said this, special relativity does come to our aid regarding slower than light travel. For instance, travelling at 99% of the speed of light to the nearest star Alpha Centauri it would take over 4.3 years according to a stationary observer watching you. However, because of time dilation, the time elapsed for an occupant of the spacecraft would only be 7 months. Travel at 99.9% of the speed of light and this goes down to 70 days. Neat huh? The only problem as far as the physics is concerned is finding an energy source which could accelerate you to such a speed.

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    Senior Member Rook's Avatar
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    Quote Originally Posted by Northumbrian View Post
    Having said this, special relativity does come to our aid regarding slower than light travel. For instance, travelling at 99% of the speed of light to the nearest star Alpha Centauri it would take over 4.3 years according to a stationary observer watching you. However, because of time dilation, the time elapsed for an occupant of the spacecraft would only be 7 months. Travel at 99.9% of the speed of light and this goes down to 70 days. Neat huh? The only problem as far as the physics is concerned is finding an energy source which could accelerate you to such a speed.
    In practical terms, even traveling at 99% the speed of light, it would take you longer than that to reach Alpha Centauri - the human body can not tolerate accelerating that rapidly. I remember reading somewhere that it'd take years of steady acceleration to reach the speed of light, and then the same steady deceleration to slow down before we reach our target. So even if we could reach 99% speed of light in 60 seconds, our fragile bodies wouldn't survive such acceleration
    Last edited by Rook; 01-21-2013 at 01:00 PM.

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