[math-fun] EM propulsion drive
A photon rocket would produce momentum p by consuming energy E=p*c. That's a very poor E/p ratio (since c is large). Meanwhile, old fashioned chemical rockets and ion drives emitting mass m at speed v, supply momentum p=m*v, at energy cost E=m*v^2/2. Here the E/p ratio is v/2. That is far superior to the photon drive. Like 30000 times better. But the photon rocket would have the advantage that no mass would be consumed (if the energy supply was free, e.g. came from solar power). Even that advantage might be small because you could save mass by making v large (e.g. using small particle accelerator as ion rocket) still tremendously outperforming the photon rocket on E/p ratio, while only consuming small mass. And also since your solar panel would provide more "thrust" than your photon rocket that it powered. So... I conclude the photon rocket idea is bullshit.
On 5/19/2015 5:31 PM, Warren D Smith wrote:
A photon rocket would produce momentum p by consuming energy E=p*c. That's a very poor E/p ratio (since c is large).
Meanwhile, old fashioned chemical rockets and ion drives emitting mass m at speed v, supply momentum p=m*v, at energy cost E=m*v^2/2. Here the E/p ratio is v/2. That is far superior to the photon drive. Like 30000 times better.
Of course that's because you're not counting the mc^2 energy you're losing. Which is reasonable if you have no way to convert it to kinetic energy.
But the photon rocket would have the advantage that no mass would be consumed (if the energy supply was free, e.g. came from solar power). Even that advantage might be small because you could save mass by making v large (e.g. using small particle accelerator as ion rocket) still tremendously outperforming the photon rocket on E/p ratio, while only consuming small mass. And also since your solar panel would provide more "thrust" than your photon rocket that it powered.
Hence the solar sail idea. Brent
So... I conclude the photon rocket idea is bullshit.
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I don't get the sense that they are talking about a traditional photon drive--they are using the "quantum vacuum". In theory, put enough energy into the vacuum and you can produce a virtual pair of oppositely charged particles. With enough hand waving, you can separate the (now "real") particles and then accelerate both out the exhaust and send the rocket forward. Sounds similar to Hawking radiation at the event horizon of a black hole. --R -----Original Message----- From: math-fun [mailto:math-fun-bounces@mailman.xmission.com] On Behalf Of Warren D Smith Sent: Tuesday, May 19, 2015 8:31 PM To: math-fun@mailman.xmission.com Subject: [math-fun] EM propulsion drive A photon rocket would produce momentum p by consuming energy E=p*c. That's a very poor E/p ratio (since c is large). Meanwhile, old fashioned chemical rockets and ion drives emitting mass m at speed v, supply momentum p=m*v, at energy cost E=m*v^2/2. Here the E/p ratio is v/2. That is far superior to the photon drive. Like 30000 times better. But the photon rocket would have the advantage that no mass would be consumed (if the energy supply was free, e.g. came from solar power). Even that advantage might be small because you could save mass by making v large (e.g. using small particle accelerator as ion rocket) still tremendously outperforming the photon rocket on E/p ratio, while only consuming small mass. And also since your solar panel would provide more "thrust" than your photon rocket that it powered. So... I conclude the photon rocket idea is bullshit. _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
On Tue, May 19, 2015 at 8:44 PM, Richard E. Howard <rich@richardehoward.com> wrote:
I don't get the sense that they are talking about a traditional photon drive--they are using the "quantum vacuum".
They're talking about stuff they pulled out of their rear ends. There's no such thing as the "quantum vacuum virtual plasma". http://blogs.discovermagazine.com/outthere/2014/08/06/nasa-validate-imposibl... -- Mike Stay - metaweta@gmail.com http://www.cs.auckland.ac.nz/~mike http://reperiendi.wordpress.com
NASA's Eagleworks lab spent $50,000 to evaluate the supposed drive. http://nasawatch.com/archives/2014/06/jscs-warp-drive.html On Tue, May 19, 2015 at 9:16 PM, Mike Stay <metaweta@gmail.com> wrote:
On Tue, May 19, 2015 at 8:44 PM, Richard E. Howard <rich@richardehoward.com> wrote:
I don't get the sense that they are talking about a traditional photon drive--they are using the "quantum vacuum".
They're talking about stuff they pulled out of their rear ends. There's no such thing as the "quantum vacuum virtual plasma".
http://blogs.discovermagazine.com/outthere/2014/08/06/nasa-validate-imposibl... -- Mike Stay - metaweta@gmail.com http://www.cs.auckland.ac.nz/~mike http://reperiendi.wordpress.com
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On Wed, May 20, 2015 at 8:11 AM, Jeff Caldwell <jeffrey.d.caldwell@gmail.com> wrote:
NASA's Eagleworks lab spent $50,000 to evaluate the supposed drive.
Sure; their job is to evaluate wild claims in the hope that one of them pans out. This one claims to violate the principle of conservation of momentum; given the energy scales they're talking about, particle colliders would have seen such a violation almost immediately. There's absolutely no evidence for such a violation beyond their one very suspicious experiment. -- Mike Stay - metaweta@gmail.com http://www.cs.auckland.ac.nz/~mike http://reperiendi.wordpress.com
I apologize for not being clear. A $50,000 test of such an extraordinary claim is practically meaningless unless the results are blindingly obvious. On Wed, May 20, 2015 at 12:58 PM, Mike Stay <metaweta@gmail.com> wrote:
On Wed, May 20, 2015 at 8:11 AM, Jeff Caldwell <jeffrey.d.caldwell@gmail.com> wrote:
NASA's Eagleworks lab spent $50,000 to evaluate the supposed drive.
Sure; their job is to evaluate wild claims in the hope that one of them pans out.
This one claims to violate the principle of conservation of momentum; given the energy scales they're talking about, particle colliders would have seen such a violation almost immediately. There's absolutely no evidence for such a violation beyond their one very suspicious experiment. -- Mike Stay - metaweta@gmail.com http://www.cs.auckland.ac.nz/~mike http://reperiendi.wordpress.com
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You'd better wave your hands an awful lot here, since you're violating conservation of energy. Andy On Tue, May 19, 2015 at 11:44 PM, Richard E. Howard <rich@richardehoward.com> wrote:
I don't get the sense that they are talking about a traditional photon drive--they are using the "quantum vacuum".
In theory, put enough energy into the vacuum and you can produce a virtual pair of oppositely charged particles. With enough hand waving, you can separate the (now "real") particles and then accelerate both out the exhaust and send the rocket forward. Sounds similar to Hawking radiation at the event horizon of a black hole.
--R
-----Original Message----- From: math-fun [mailto:math-fun-bounces@mailman.xmission.com] On Behalf Of Warren D Smith Sent: Tuesday, May 19, 2015 8:31 PM To: math-fun@mailman.xmission.com Subject: [math-fun] EM propulsion drive
A photon rocket would produce momentum p by consuming energy E=p*c. That's a very poor E/p ratio (since c is large).
Meanwhile, old fashioned chemical rockets and ion drives emitting mass m at speed v, supply momentum p=m*v, at energy cost E=m*v^2/2. Here the E/p ratio is v/2. That is far superior to the photon drive. Like 30000 times better.
But the photon rocket would have the advantage that no mass would be consumed (if the energy supply was free, e.g. came from solar power). Even that advantage might be small because you could save mass by making v large (e.g. using small particle accelerator as ion rocket) still tremendously outperforming the photon rocket on E/p ratio, while only consuming small mass. And also since your solar panel would provide more "thrust" than your photon rocket that it powered.
So... I conclude the photon rocket idea is bullshit.
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participants (6)
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Andy Latto -
Jeff Caldwell -
meekerdb -
Mike Stay -
Richard E. Howard -
Warren D Smith