APOD: Earth size Kepler 186f (2014 Apr 19)

[Ann]

When I made my model of the inner Solar system, I was struck by how small the inner planets were and how far they were from one another. But I was equally amazed at how close the Moon was to the Earth. The distance between the Earth and the Moon, by the way, is about one light-second.

The fact that NASA has sent people to the Moon does not prove that it will ever be possible to send people to other planets in our own Solar system, light-minutes or light-hours away, let alone to planets in other solar systems many light-years away.

Ann

[rj rl]

The fact that NASA has sent people to the Moon does not prove that it will ever be possible to send people to other planets in our own Solar system, light-minutes or light-hours away, let alone to planets in other solar systems many light-years away.

Ann

sadly, yes. A way to think about it from a mathematical point of view: convergent series start lively too Not only do they never reach infinity, but they can't even get close to almost any preset threshold.

[supamario]

The fact that NASA has sent people to the Moon does not prove that it will ever be possible to send people to other planets in our own Solar system, light-minutes or light-hours away, let alone to planets in other solar systems many light-years away.

Ann

sadly, yes. A way to think about it from a mathematical point of view: convergent series start lively too Not only do they never reach infinity, but they can't even get close to almost any preset threshold.

No, you are both thinking in linear terms. Light speed is not the way to travel. Its impractical. Folding space via wormhole is the solution. This also eliminates the Twin Paradox.

[geckzilla]

The fact that NASA has sent people to the Moon does not prove that it will ever be possible to send people to other planets in our own Solar system, light-minutes or light-hours away, let alone to planets in other solar systems many light-years away.

Ann

sadly, yes. A way to think about it from a mathematical point of view: convergent series start lively too Not only do they never reach infinity, but they can't even get close to almost any preset threshold.

No, you are both thinking in linear terms. Light speed is not the way to travel. Its impractical. Folding space via wormhole is the solution. This also eliminates the Twin Paradox.

I prefer magical solutions over practical ones too. Willing the house to clean itself hasn't worked out yet, though.

[supamario]

sadly, yes. A way to think about it from a mathematical point of view: convergent series start lively too Not only do they never reach infinity, but they can't even get close to almost any preset threshold.

No, you are both thinking in linear terms. Light speed is not the way to travel. Its impractical. Folding space via wormhole is the solution. This also eliminates the Twin Paradox.

I prefer magical solutions over practical ones too. Willing the house to clean itself hasn't worked out yet, though.

Maybe not in our lifetime, but today's magic is tomorrow's science - assuming we dont destroy ourselves beforehand.

[DavidLeodis]

geckzilla. Your "I prefer magical solutions over practical ones too. Willing the house to clean itself hasn't worked out yet, though" made me . I keep hoping that somewhere some friendly bacteria or whatever evolves that lives happily on house dust (which I believe is mostly shed skin)! For now though its still the vacuum cleaner!

[Chris Peterson]

Maybe not in our lifetime, but today's magic is tomorrow's science - assuming we dont destroy ourselves beforehand.

Not really. For the most part, today's science is also tomorrow's science. Once we know something about the laws of nature, we rarely find out that we are wrong, except perhaps in find details.

[Anthony Barreiro]

Maybe not in our lifetime, but today's magic is tomorrow's science - assuming we dont destroy ourselves beforehand.

Not really. For the most part, today's science is also tomorrow's science. Once we know something about the laws of nature, we rarely find out that we are wrong, except perhaps in [fine] details.

i'm not arguing for the possibilities of faster than light travel, wormhole shortcuts, or counter-entropic housecleaning. But I do think we need to recognize that even an entirely correct natural law can turn out to be incomplete. The textbook example is exactly Einsteinian relativity explaining facts that cannot be explained by Newtonian mechanics.

[Chris Peterson]

i'm not arguing for the possibilities of faster than light travel, wormhole shortcuts, or counter-entropic housecleaning. But I do think we need to recognize that even an entirely correct natural law can turn out to be incomplete. The textbook example is exactly Einsteinian relativity explaining facts that cannot be explained by Newtonian mechanics.

Exactly... which is what I was referring to by the details. Also, I'm really only considering ideas we've refined in the last century or so, as the scientific approach came into its full maturity. We simply don't see well supported scientific theories describing major ideas being replaced with radically different ones anymore. I think that's because in most areas of our scientific understanding of nature, we're homing in on accurate descriptions. Once you get to the right answer, it doesn't change, no matter how far in the future you go, no matter how advanced your science becomes.

[supamario]

i'm not arguing for the possibilities of faster than light travel, wormhole shortcuts, or counter-entropic housecleaning. But I do think we need to recognize that even an entirely correct natural law can turn out to be incomplete. The textbook example is exactly Einsteinian relativity explaining facts that cannot be explained by Newtonian mechanics.

Exactly... which is what I was referring to by the details. Also, I'm really only considering ideas we've refined in the last century or so, as the scientific approach came into its full maturity. We simply don't see well supported scientific theories describing major ideas being replaced with radically different ones anymore. I think that's because in most areas of our scientific understanding of nature, we're homing in on accurate descriptions. Once you get to the right answer, it doesn't change, no matter how far in the future you go, no matter how advanced your science becomes.

This is also linear thinking. Gravity is still poorly understood. The concept of teleportation is proven, but only in its infancy. Once the breakthroughs occur, and they will in time, it opens up a new branch of possibilities.

[Chris Peterson]

This is also linear thinking. Gravity is still poorly understood. The concept of teleportation is proven, but only in its infancy. Once the breakthroughs occur, and they will in time, it opens up a new branch of possibilities.

Gravity is well understood. And teleportation is a quantum effect, not applicable to much beyond single particles.

Gravity will become better understood, but that will not result in general relativity being invalidated. Quantum teleportation will become better understood, but that will not result in something like teleportation devices (and even if it did, the speed of light would still be a limit).

[supamario]

This is also linear thinking. Gravity is still poorly understood. The concept of teleportation is proven, but only in its infancy. Once the breakthroughs occur, and they will in time, it opens up a new branch of possibilities.

Gravity is well understood. And teleportation is a quantum effect, not applicable to much beyond single particles.

Gravity will become better understood, but that will not result in general relativity being invalidated. Quantum teleportation will become better understood, but that will not result in something like teleportation devices (and even if it did, the speed of light would still be a limit).

You are thinking in the present. Gravity is not sufficiently understood to manipulate it. Teleportation, at present, is only limited to particles. I envisage a future machine that can intensify gravity to bend space and continuously teleport itself to the deepest end of what it can bend. Sure, science fiction for now..

[Chris Peterson]

You are thinking in the present. Gravity is not sufficiently understood to manipulate it. Teleportation, at present, is only limited to particles. I envisage a future machine that can intensify gravity to bend space and continuously teleport itself to the deepest end of what it can bend. Sure, science fiction for now..

Methinks you confuse science fiction with reality.

We can certainly manipulate gravity. For instance, we can create gravitational waves. What do you mean by "manipulate"? Perhaps you are talking about some sort of artificial gravity, or gravity shielding? You're right, we can't do that. And there's a reason. Because it probably isn't physically possible. And your teleportation concept isn't grounded in reality at all.

We do understand these things quite well. Well enough to have a good idea about what is and is not possible.

[supamario]

You are thinking in the present. Gravity is not sufficiently understood to manipulate it. Teleportation, at present, is only limited to particles. I envisage a future machine that can intensify gravity to bend space and continuously teleport itself to the deepest end of what it can bend. Sure, science fiction for now..

Methinks you confuse science fiction with reality.

We can certainly manipulate gravity. For instance, we can create gravitational waves. What do you mean by "manipulate"? Perhaps you are talking about some sort of artificial gravity, or gravity shielding? You're right, we can't do that. And there's a reason. Because it probably isn't physically possible. And your teleportation concept isn't grounded in reality at all.

We do understand these things quite well. Well enough to have a good idea about what is and is not possible.

Yes, yes, of course.. Perhaps I best flee lest I be burned at the stake.

[Chris Peterson]

Yes, yes, of course.. Perhaps I best flee lest I be burned at the stake.

This forum does not employ such primitive means. Stray too far, and a moderator will send energy beams out of your monitor, reducing you to a pile of ash in your chair.

[supamario]

Yes, yes, of course.. Perhaps I best flee lest I be burned at the stake.

This forum does not employ such primitive means. Stray too far, and a moderator will send energy beams out of your monitor, reducing you to a pile of ash in your chair.

Yes, quite. Total fiction back in the day (computer?? energy beams??? utter nonsense), but today, not outside the realms of possibility - if it was so desired.

[BDanielMayfield]

Given enough time however, an advanced sentient race could theoretically completely colonize a Milky Way sized galaxy even with slow boat to China sub-light interstellar travel.

Let’s say that truly Earth-like, suitable for colonization planets are out there and that on average about 1/1,000 stars has one. Our Galaxy has at least 100 billion stars, so that would give us at least 100 million potential new homes! But on average, how far apart would these 1 out of a thousand stars be? That depends on stellar density:

Stellar density is the average number of stars within a unit volume. It is similar to the stellar mass density, which is the total solar masses (MSun) found within a unit volume. Typically, the volume used by astronomers to describe the stellar density is a cubic parsec (pc³).

In the solar neighborhood, this value can be determined from surveys of nearby stars, combined with estimates of the number of faint stars that may have been missed. The true stellar density near the Sun is estimated as 0.004 stars per cubic light year, or 0.14 stars pc^-3. When combined with estimates of the stellar masses, this yields a mass density estimate of 4 × 10^-24 g/cm3. The density estimate varies across space, with the density decreasing rapidly in the direction out of the galactic plane.

The figure 0.004 stars per cubit light year works out to 1 star per 250 cubic light years. (That really puts the emptyness of inter-stellar space into perspective, doesn’t it? But that’s beside the point.) To get a volume of local space containing 1,000 stars we’d need a volume of space 250,000 cubic light years large.

So, how far apart would the “Earths” be in this hypothetical galaxy? The sides of a cube 250,000 ly³ large is the cube root of 250,000, which is only about 63 light years. So if my math isn’t in error, (and please correct me if it is) the average distance between truly Earth-like, colonizable worlds would be about 63 light years (if there is one per 1,000 stars).

I’ll leave the thorny details of how to actually build a ship that could make up to 100 light year trips as a group exercise.

[Chris Peterson]

Given enough time however, an advanced sentient race could theoretically completely colonize a Milky Way sized galaxy even with slow boat to China sub-light interstellar travel.

Indeed. And it doesn't take much time at all. Which brings up the question of where everyone is.

[BDanielMayfield]

Yes. The good ol’ Fermi paradox!

See: http://en.wikipedia.org/wiki/Fermi_paradox

[Ann]

Things were better in Star Trek. Your vessel moved at warp speed, you came across planets all the time, the planets were basically all "class M planets" and you could beam down to them and walk around on them without even using a gas mask. (Even if, occasionally, you might have some problems beaming up again.)

Click to play embedded YouTube video.

Ann

[Beyond]

300,000 kilometers per second. It's not just a good idea -- it's the law.

And we have a vastly greater understanding of the law than we did in 1500.

But not as good as we will in the future! Now, where are those loopholes hidden?? There's always loopholes, ya know.

[Beyond]

Given enough time however, an advanced sentient race could theoretically completely colonize a Milky Way sized galaxy even with slow boat to China sub-light interstellar travel.

Indeed. And it doesn't take much time at all. Which brings up the question of where everyone is.

They've found the loopholes.

[geckzilla]

If anyone here is working on or knows of anyone working on feasible FTL or wormhole travel, we might have a discussion. Otherwise, it's just some kind of weird science faith that sci-fi will somehow eventually come true. Believe that if you want but don't try to tell the rest of us we are wrong for taking a look at the facts and saying it doesn't look very likely.

[supamario]

If anyone here is working on or knows of anyone working on feasible FTL or wormhole travel, we might have a discussion. Otherwise, it's just some kind of weird science faith that sci-fi will somehow eventually come true. Believe that if you want but don't try to tell the rest of us we are wrong for taking a look at the facts and saying it doesn't look very likely.

And Galileo shall remain imprisoned unless someone is working on a "space probe", what nonsense, to prove his utterly ridiculous notion of a heliocentric system.

[Nitpicker]

Given enough time however, an advanced sentient race could theoretically completely colonize a Milky Way sized galaxy even with slow boat to China sub-light interstellar travel.

Indeed. And it doesn't take much time at all. Which brings up the question of where everyone is.

For those who think artificial intelligence will one day become a reality, it is possible that the lack of visiting or invading extraterrestrial robots, is also a very relevant bit of evidence hinting that AI may be unlikely.