Quote from: ppnl on 05/01/2015 09:28 pmQuote from: bad_astra on 05/01/2015 09:13 pmQuote from: gospacex on 05/01/2015 03:16 pmIT IS NOT THE SAME!!!!!!Having reaction mass expelled *changes everything*! For one, now you need to include reaction mass' kinetic energy into energy balance.Constant acceleration reactionless drive of any type violates COE.Does a magsail?A magsail is neither constant acceleration nor reaction-less. It is true that it does not carry its reaction mass with it but it is reacting against an external medium. But then so does a car, airplane or boat.It is argued that the EM-drive is also reacting against an external medium, in its case the quantum vacuum.
Quote from: bad_astra on 05/01/2015 09:13 pmQuote from: gospacex on 05/01/2015 03:16 pmIT IS NOT THE SAME!!!!!!Having reaction mass expelled *changes everything*! For one, now you need to include reaction mass' kinetic energy into energy balance.Constant acceleration reactionless drive of any type violates COE.Does a magsail?A magsail is neither constant acceleration nor reaction-less. It is true that it does not carry its reaction mass with it but it is reacting against an external medium. But then so does a car, airplane or boat.
Quote from: gospacex on 05/01/2015 03:16 pmIT IS NOT THE SAME!!!!!!Having reaction mass expelled *changes everything*! For one, now you need to include reaction mass' kinetic energy into energy balance.Constant acceleration reactionless drive of any type violates COE.Does a magsail?
IT IS NOT THE SAME!!!!!!Having reaction mass expelled *changes everything*! For one, now you need to include reaction mass' kinetic energy into energy balance.Constant acceleration reactionless drive of any type violates COE.
...Those people do not know the struggling of a scientist to get just a little more funding in their lab where only 3 or 4 other colleagues work with them. Eagleworks has an old dying RF amp and they do not even have the bucks to replace it… Paul had to build the copper frustum at home, in his wife's dining room! Really people would be shocked if they knew that....
Commander Chris Hadfield just tweeted it to his 1.3 million followers.
Quote from: Art Harmon on 05/01/2015 07:25 pmSo let's assume the EM drive works as described and Alpha Centauri can be reached in approximately 130 earth years accounting for acceleration, cruising and deceleration. Can anyone calculate the approximate time dilation spent? (i.e. the theory of relativity that shows time slowing down relative to earth time and stops at light speed.) Obviously gravitational effects on time dilation would probably be impossible to factor in. If time were slowed down enough would it allow reaching Alpha Centauri in a generation or two? Assuming one didn't die of radiation poisoning, a spec of dust piercing a hole through them at that speed, or outright insanity. I get around a month difference.
So let's assume the EM drive works as described and Alpha Centauri can be reached in approximately 130 earth years accounting for acceleration, cruising and deceleration. Can anyone calculate the approximate time dilation spent? (i.e. the theory of relativity that shows time slowing down relative to earth time and stops at light speed.) Obviously gravitational effects on time dilation would probably be impossible to factor in. If time were slowed down enough would it allow reaching Alpha Centauri in a generation or two? Assuming one didn't die of radiation poisoning, a spec of dust piercing a hole through them at that speed, or outright insanity.
Quote from: Mulletron on 05/01/2015 09:39 pmQuote from: Art Harmon on 05/01/2015 07:25 pmSo let's assume the EM drive works as described and Alpha Centauri can be reached in approximately 130 earth years accounting for acceleration, cruising and deceleration. Can anyone calculate the approximate time dilation spent? (i.e. the theory of relativity that shows time slowing down relative to earth time and stops at light speed.) Obviously gravitational effects on time dilation would probably be impossible to factor in. If time were slowed down enough would it allow reaching Alpha Centauri in a generation or two? Assuming one didn't die of radiation poisoning, a spec of dust piercing a hole through them at that speed, or outright insanity. I get around a month difference.Yep, me too. v=0.067c at turnaround, t-tau = 36 days for 0.001 g's
Quote from: Prunesquallor on 05/02/2015 04:44 amQuote from: Mulletron on 05/01/2015 09:39 pmQuote from: Art Harmon on 05/01/2015 07:25 pmSo let's assume the EM drive works as described and Alpha Centauri can be reached in approximately 130 earth years accounting for acceleration, cruising and deceleration. Can anyone calculate the approximate time dilation spent? (i.e. the theory of relativity that shows time slowing down relative to earth time and stops at light speed.) Obviously gravitational effects on time dilation would probably be impossible to factor in. If time were slowed down enough would it allow reaching Alpha Centauri in a generation or two? Assuming one didn't die of radiation poisoning, a spec of dust piercing a hole through them at that speed, or outright insanity. I get around a month difference.Yep, me too. v=0.067c at turnaround, t-tau = 36 days for 0.001 g'sThat violates energy conservation. You're talking about way more kinetic energy than you put into it in the first place.
Quote from: Robotbeat on 05/02/2015 05:01 amQuote from: Prunesquallor on 05/02/2015 04:44 amQuote from: Mulletron on 05/01/2015 09:39 pmQuote from: Art Harmon on 05/01/2015 07:25 pmSo let's assume the EM drive works as described and Alpha Centauri can be reached in approximately 130 earth years accounting for acceleration, cruising and deceleration. Can anyone calculate the approximate time dilation spent? (i.e. the theory of relativity that shows time slowing down relative to earth time and stops at light speed.) Obviously gravitational effects on time dilation would probably be impossible to factor in. If time were slowed down enough would it allow reaching Alpha Centauri in a generation or two? Assuming one didn't die of radiation poisoning, a spec of dust piercing a hole through them at that speed, or outright insanity. I get around a month difference.Yep, me too. v=0.067c at turnaround, t-tau = 36 days for 0.001 g'sThat violates energy conservation. You're talking about way more kinetic energy than you put into it in the first place.The OP qualified his question "So let's assume the EM Drive works as described..." My response was based on that qualification.
So I wanted to ask...The wave inside the resonant cavity is a standing wave, and it can exert force on the cavity itself. And in regards to its motion, that standing wave can be construed as a soliton. Ordinarily, a soliton on its own (outside of a resonant cavity) is said to be a "delicate balance of linear and nonlinear effects which counter dispersion" - but here we have a resonant cavity to counter the dispersion, with the consequence that cavity has force interaction with the trapped wave.Is it possible that the power feed to the asymmetric cavity can somehow force the soliton to move, and thus make the cavity move with it? And thus your apparatus is then "surfing the wave"? (ie. surfing the soliton)
I have to think that this is only necessary in order to preserve the validity of the current understanding of such things.
In any case, whatever effect one can conjecture, the challenge is not only to prove the existence of the effect but just as important, to demonstrate conservation of momentum for a cavity accelerated under such an effect
actually no. It was outside critics that insisted they need to see how it performed in a vacuum chamber.
Quote from: Rodal on 05/02/2015 02:00 pmIn any case, whatever effect one can conjecture, the challenge is not only to prove the existence of the effect but just as important, to demonstrate conservation of momentum for a cavity accelerated under such an effect Alright, so the standing wave loses energy in an amount that offsets the kinetic energy gain associated with acceleration - and this is supposed to satisfy conservation of energy. And conservation of momentum is satisfied by using energy-mass equivalency?I was just wondering what the mechanism is by which pumping up the standing wave then creates a net force on the cavity.Here's a debunking by Greg Egan, showing why you can't have net force just because the cavity happens to be asymmetric:http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Simple.html
Quote from: sanman on 05/02/2015 03:22 pmQuote from: Rodal on 05/02/2015 02:00 pmIn any case, whatever effect one can conjecture, the challenge is not only to prove the existence of the effect but just as important, to demonstrate conservation of momentum for a cavity accelerated under such an effect Alright, so the standing wave loses energy in an amount that offsets the kinetic energy gain associated with acceleration - and this is supposed to satisfy conservation of energy. And conservation of momentum is satisfied by using energy-mass equivalency?I was just wondering what the mechanism is by which pumping up the standing wave then creates a net force on the cavity.Here's a debunking by Greg Egan, showing why you can't have net force just because the cavity happens to be asymmetric:http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Simple.htmlGreg Egan is just showing the standing wave solution to Maxwell's equation for a truncated cone for mode shapes that have constant field in the transverse, azimuthal direction. The solutions shown by Egan are known since the 1930's. That Maxwell's equations and special relativity satisfy conservation of momentum is known in general, for any problem, for any geometrical shape. Thus, Egan is just "debunking" attempts (as done by Roger Shawyer for example or by Prof. Yang in China) trying to justify EM Drive space propulsion just using Maxwell's equations and special relativity. Egan's paper does not and cannot debunk Dr. White's conjecture for example, or Prof. Woodward's conjecture. Dr. White's conjecture can be objected on the grounds that it implies a mutable and degradable quantum vacuum, for example, but not solely on the grounds discussed by Egan.
...And the computer simulations ...are based on Maxwell's Equations which literally don't allow something like the EM-drive as they conserve both momentum and energy perfectly. .....