Subject:
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Re: Some great Space info and dicussion
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Newsgroups:
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lugnet.space
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Date:
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Tue, 21 Jan 2003 09:56:02 GMT
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Viewed:
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967 times
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Ahh, but that assumes you have the technology. His theory is that you
> will get blasted to oblivion before you get the technology. There's • also
> the time factor. You don't have all that blasted much time to react to
> something approaching at relativistic speeds (remember, if it's
> approaching at 90% the speed of light, you only have 10% of the time it
> takes for the object to reach you). Another part of his idea was that
> perhaps SETI isn't such a good idea: "Hey fellas, we're a nascent
> technological civilization, come blast us to oblivion before we learn
> anything dangerous."
Unless acceleration is almost instantaneous, the waste energy of
whatever accelerates the rock to light speed will reach you long before
the rock does.
Assuming that the rock's rest mass is 1000 tonnes, accelerating it to
90% of light speed would require 2.0647*10^23 joules of energy. This is
an energy release 4.9324*10^7 times the 50 megaton Tsar Bomba, the
largest nuclear weapon ever detonated by humans.
Don't tell me that an energy release of this magnitude would not be
noticed by the opposing side. If you're going to generate that much
energy, you might as well directly apply it to the target to avoid
wasteful expenditure of resources. Note that the figures above only
display the energy required to accelerate the rock to 90% light speed.
Due to inefficiencies, a power source capable of generating within the
necessary time much more energy than is required to accelerate the rock,
meaning several orders of magnitude, would be required.
Let's not even get into the necessary capabilities of the heat
dissipation system.
On the other hand, knocking rocks into a planet is a much simpler
proposition. One only has to reduce the kinetic energy of a rock
orbiting the target to less than that of the rock's gravitational
binding energy.
If you need to kill a planet, sending into the target's gravity well a
rock of huge mass will require much less technological capabilities than
accelerating a rock to relativistic velocities.
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Message has 2 Replies:
 | | Re: Some great Space info and dicussion
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| (...) Holy Moly! You sure know your physics! :) I would add though, that if the attacker in this scenario were concerned with "expenditure of resources" then they would be very unwise to ever consider killing a planet known to harbor life. Let's for (...) (21 years ago, 21-Jan-03, to lugnet.space)
| | | Re: Some great Space info and dicussion
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| (...) That too requires the target civilization to recognize it (the energy wastage) for what it is. If there *is* wastage to detect in the direction of the target--again, not something we can be sure of, necessarily; it may be that one has to be, (...) (21 years ago, 22-Jan-03, to lugnet.space)
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Message is in Reply To:
| | Re: Some great Space info and dicussion
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| (...) Ahh, but that assumes you have the technology. His theory is that you will get blasted to oblivion before you get the technology. There's also the time factor. You don't have all that blasted much time to react to something approaching at (...) (21 years ago, 16-Jan-03, to lugnet.space)
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