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Why we are unlikely to ever leave the solar system.

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Re: Why we are unlikely to ever leave the solar system.

#141

Post by weavejester »

troels wrote: post #92
adrianN wrote: post #83

Earlier quoted context omitted.

No, you just require a sufficient pressure to overcome the repulsive forces between the particles to collapse them to a singularity. That's why people were afraid of the LHC.

Ah .. And normally (If that is a word which makes sense in this context), the mass of a giant object (Like a star) would be the way to create this pressure? But theoretically you could do it by other means?

You essentially need to cram a lot of mass into a very small space, which is equivalent to cramming a lot of energy into a very small space.

So, theoretically, you can get a bunch of very, very large lasers, focus them all upon a very small point, and if you pump enough energy into the system you wind up with a black hole.

Re: Why we are unlikely to ever leave the solar system.

#142

Post by ctdonath »

scott_s wrote: post #91
rosser wrote: post #47

Earlier quoted context omitted.

Not the GP, but, in short, because space is very, very big, and very, very empty. By way of extremely loose analogy, consider a large pea (1 cm in diameter) hanging by a string in the middle of a football stadium. Let's say that represents our solar system (minus the Oort cloud) and its environs. That's a slightly scaled-down version of Stross' analogy, where the diameter of the solar system (again, minus the Oort cl…

Yes. For more perspective, the average density of the universe is roughly 3-6 hydrogen atoms per cubic meter.

Gathering all the interstellar hydrogen in a swath of space 1x1m wide and 1 light year long (i.e. everything you can collect with a 1-meter scoop from here to ¼ the way to Alpha Centauri) yields 0.01 grams of hydrogen.

A sobering thought regarding the inevitable "interstellar ramjet" suggestion.

Re: Why we are unlikely to ever leave the solar system.

#143

Post by redthrowaway »

iwwr wrote: post #117
redthrowaway wrote: post #89

Earlier quoted context omitted.

>but that may be corrected in a few generations. Or not, as the case may be. That's why you send out many such probes. You would have to assume that most attempts would fail. You are, after all, attempting to transplant human life with no human oversight. Either way, it's merely prolonging the inevitable. The Sun has about 5 billion years of fuel left, which is coincidentally about the time the Milky Way will collide…

That scenario is impossible in an expanding universe. Regions of space eventually become disconnected from each other. There wouldn't be one computational entity overall, although there may be little dominant AIs inside these disconnected space bubbles.

It's a science fiction story written in 1956.

Re: Why we are unlikely to ever leave the solar system.

#144

Post by cpeterso »

michaelcampbell wrote: post #124
cletus wrote: post #6

That's a good, grounded assessment of the scale of the problem. I too believe that the human colonization of space, even near-space (ie within the orbit of the Moon) is a long way off. The energy costs are simply too high and resources too cheap on the Earth to make it viable (in spite of typical SF fodder of asteroid mining). This is a problem because with 6.5 billion people we're using up resources. Fast. Anyway, I…

I think a more realistic scenario, at least in the short/medium term (for relative values of "short" and "medium"), will be to limit human population to a sustainable level. It will be ugly, but I think in a few generations' time we'll see it happening, either by explicit means or evolutionary. I'm thinking pandemics brought on by overpopulation, and the evolution of diseases, not our evolution, although that too may…

I believe the UN's population models predict the world population will peak at ~9B in around 2050 and then fall. Most developed countries already have negative population growth (from birth rate below replacement levels, ignoring immigration).

Re: Why we are unlikely to ever leave the solar system.

#145

Post by pavel_lishin »

billswift wrote: post #101
guelo wrote: post #38

As impossible as the physics seems I think the social problems are bigger. Scientists are currently unable to convince people to act against the potential catastrophe of global warming. Humans are too stupid to organize a planet wide self preservation effort that requires any significant amount of resources. I think the more likely scenario for humanity over the next 10 thousand years is several cycles of civilizatio…

Humans are too smart to let a bunch of bureaucrats with their pseudo-scientific rationalizations destroy the economy in the pursuit of more power for the bureaucracies.

I like the ambiguity of your response.

Re: Why we are unlikely to ever leave the solar system.

#146

Post by cpeterso »

Detrus wrote: post #15
cletus wrote: post #6

That's a good, grounded assessment of the scale of the problem. I too believe that the human colonization of space, even near-space (ie within the orbit of the Moon) is a long way off. The energy costs are simply too high and resources too cheap on the Earth to make it viable (in spite of typical SF fodder of asteroid mining). This is a problem because with 6.5 billion people we're using up resources. Fast. Anyway, I…

Black holes spaceships are the ticket with our current understanding of physics. They can carry a large and heavy cargo in ship form or can push small planets slowly in a desired direction. The travel times for black hole ships are reasonable too, about six years to Proxima Centauri. It beats the other sci-fi concepts like fusion, Orion, anti matter and solar sails. Funny how solar sails seem like the easier option t…

If we can't travel faster than the speed of light (a reasonably safe assumption), maybe we can take intergalactic shortcuts like black holes. So it seems to me that Battlestar Galactica-style "jump" drives (or Borg transwarp conduits) are more likely than Star Trek-style warp drives.

Re: Why we are unlikely to ever leave the solar system.

#147

Post by drcube »

itg wrote: post #109
billswift wrote: post #101

Earlier quoted context omitted.

Humans are too smart to let a bunch of bureaucrats with their pseudo-scientific rationalizations destroy the economy in the pursuit of more power for the bureaucracies.

And this is exactly the type of short-sighted thinking that dooms us. The vast majority of scientists have come to a consensus yet you don't like it so label them bureaucrats with some sinister motive of destroying the economy behind it.

Just because we know there is a problem doesn't really mean anything. That's just the beginning. Ask yourself these questions:

How much does/will the problem cost us? IS there a solution? How much will the solution cost?

Then you do cost benefit analysis and decide the best course of action. THEN you try to talk everybody else into it.

I'm happy to concede global warming is happening and will only get worse. Hell, I was one of the first people I know to understand and accept that. I just haven't seen the follow up yet. It's always "Yep, got yourself a problem there", but no solution offered other than "buy a Prius".

Re: Why we are unlikely to ever leave the solar system.

#149

Post by adrianN »

nkassis wrote: post #132
adrianN wrote: post #86

Earlier quoted context omitted.

You wouldn't build one huge bomb, but instead use lots and lots of tiny bombs in an Orion-type spacecraft. That way you get a better utilisation of your energy.

Doesn't that make it even easier? But then again I think 400 megaton isn't enough. Last time I calculated it ( I probably made a ton of mistakes ;p) it was in the the 10s of thousands or something like that. Accelerating the space shuttle to 0.10c : (2,030 t * (0.10 c) (0.10*c))/210 PJ = 8700 (wolfram alpha) 2,030 mass of space shuttle in metric tons 210PJ the energy from tsar bomba. But then you have to add in the w…

You might be interested in Tsiolkovsky's rocket equation:

http://en.wikipedia.org/wiki/Rocket_equation

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