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Old 2012-10-23, 19:17   #45
chalsall
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Originally Posted by xilman View Post
Better would be to use the solar collectors to power lasers which are then used to propel the probe's sail. Coherent radiation is a much better way of transferring energy and momentum than incoherent sunlight, even after allowing for inefficiency in the laser generation.

As everyone doubtless now realises, people have been doing very serious thinking about a mission to nearby stars for several decades. I've been following their activity in some detail for over 30 years. Most of the obvious solutions using near-future technology have probably been investigated by now.
You have all, of course, read "The Mote in God's Eye" by Niven and Pournelle.
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Old 2012-10-23, 20:13   #46
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Originally Posted by chalsall View Post
You have all, of course, read "The Mote in God's Eye" by Niven and Pournelle.
Yep. Certainly laser cannon/light sail figured in that scenario, among many other technologies. Of course, there was also a means of FTL travel involving some kind of "jump points" associated with stars.

Lasers and sails also figured in the "Man-Kzin Wars" spinoffs from Niven's opus. In that series, the Kzin aliens originally show up in Sol system by way of some gravitational drive which allowed them to reach ~0.8 light speed. Then some even more bizarre aliens stop by a human colony and sell them an FTL drive. I always thought that was sort of a deus ex machina dodge on Niven's part, but then any FTL from whatever source relies on unknown-to-us technology.
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Old 2012-10-23, 20:25   #47
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Some artefacts are still usable after tens of kiloyears. They invariably have at most one moving part (hammer and anvil, for example) and have not had any significant amount of use since manufacture. I own one, a dual-edged flint hand-axe and scraper, which still works just fine. I doubt it has otherwise been used in the last 5000 years. To be fair the primitive nature of the tools which still exist is a measure of the technological level of their creators but, even so, tens of millennia is way beyond what current engineers would expect to be possible for something capable of sending data a parsec or more.
I wouldn't consider things like hammer and anvil or an axe as "moving parts" in the same sense as moving parts in a satellite or space probe: Within a probe there are things like motors, antennae or panels to be deployed, cameras with color-filters to be switched, and so on - in other words, the machine parts are changing it's position to each other, need lubrication and so on.
On the other hand, with a hammer or an axe, no part of the tool is changing its position relative to other parts of the tool, no lubrication is needed, and nothing can get stuck. OK, an axe can get blunt when used, i.e. hit against a tree or such, but still no parts get "stuck".
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Old 2012-10-23, 22:27   #48
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Guinness World Records 2013 has this to say:

fastest spacecraft speed yet achieved: Helios 2 at 157,077 MPH
Time to get to Proxima Centuari at that speed: 18,000 years

though in the numbers section of the book it says:

newest number: 0 invented back in 4th century B.C. but complex numbers on wikipedia came into things in the 1500's so I don't see how they got to this, they also list some very basic records.

Last fiddled with by science_man_88 on 2012-10-23 at 22:28
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Old 2012-10-23, 22:34   #49
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Of course, there was also a means of FTL travel involving some kind of "jump points" associated with stars.
Humans are so impatient.

Faster than Light (FTL) travel is technically possible The problem is getting from STL to FTL -- it would take infinite energy to do so.

klander... Are you familiar with the with writings of Ron Hubbard. Particularly "Ender's Game"?
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Old 2012-10-23, 22:41   #50
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Are you familiar with the with writings of Ron Hubbard. Particularly "Ender's Game"
Not really. I don't remember if I've read any of his works, but it was very long ago if at all. Am I missing something?
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Old 2012-10-23, 22:49   #51
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Not really. I don't remember if I've read any of his works, but it was very long ago if at all. Am I missing something?
Not really. And sorry, I was setting you up as the straight man.

Scientology manifested out of Hubbard's work.

I don't really know if Hubbard realized what would be done with his work.

Much like I don't know if Jesus knew what would be done with his work....
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Old 2012-10-24, 00:03   #52
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No problem. I know who Hubbard was. One does have to wonder how anyone who posthumously becomes a cult figure might feel about it.

I think Hubbard may have been someone whose works baffled or bored me when I was a very young teen. Of course, this was true (baffled) of my first encounter with Vonnegut's work: "Sirens of Titan". It was only later that I came to appreciate his messages and style. I may give Hubbard another chance someday just to see how his stuff hits me now.
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Old 2012-10-24, 00:11   #53
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Quote:
Originally Posted by chalsall View Post
Humans are so impatient.

Faster than Light (FTL) travel is technically possible The problem is getting from STL to FTL -- it would take infinite energy to do so.

klander... Are you familiar with the with writings of Ron Hubbard. Particularly "Ender's Game"?
Ender's Game was Orson Scott Card.
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Old 2012-10-24, 00:37   #54
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Quote:
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Ender's Game was Orson Scott Card.
Sorry. You are correct. Hubbard was believed to be Card's lover.
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Old 2012-10-24, 01:01   #55
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Quote:
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The point is: If we set up a mission, we (or our grand-grand-grand³...grandchildren) want data, even if it lasts 40 kiloyears or so...
It is probably worth pointing out that sending a probe now (or in 15 years) won't be worthwhile if it takes 40ka+ before any useful return on investement is expected. This is simply because in, say, 50 or 100 years some new technology will be available that will shorten the transit time to ~20ka and make the first probe a useless piece of space junk. This applies to the new 20ka probe also, as a newer technology will come around in an additional 50 to 100 years after that to reduce the travel time to 10ka, etc. It is not until you reach a point where the anticipated advance in technology is less than the anticipated travel time that it becomes viable to actually send a probe.

I suddenly got Déjà vu.
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