-
#780 by meberbs on 21 Sep, 2016 13:53
-
The particle accelerator comments are just completely confusing cause and effect. Accelerators are designed to use charged particles, because we need some way to push on them while they are in a vacuum tube. The best way to do this is via electric and magnetic forces, but that doesn't work on neutral particles. As a result we inject (still slow moving) ions into the accelerator to begin with.
...
The 20-30% c limit I used, just comes from the fact that in accelerators and in nature, detectable atoms exceeding this range seem to be fully ionized bare nuclei. Mostly protons and alpha particles in nature and up to gold and lead nuclei in accelerators.
...
We are moving to 90% of C from billion light years distant galaxies. So, a speed higher than 30% of C is not a problem if it is relatively to a distant body. If it is a problem, it is locally.
Particles in accelerators on earth are also submitted to an important proper acceleration, so it may the important proper acceleration that causes the ionization.
We can not assert that an interplanetary ship in our galaxy would be limited to 30% of C. We have no evidence for that in standard physics.
Saying this means that atoms in space would randomly ionize themselves just because they are moving fast relative to something else is just bad logic. According to everything we know, the only way we would be limited in speed relative to anything (local or distant) is by collisions with slower moving particles. (Assuming we continue having means to accelerate) Space is pretty empty, so > 90% c should be fine. -
#781 by Flyby on 21 Sep, 2016 14:04
-
....... and at least one video has to be embargoed until after a paper appears in December.....
The public entering that...euhmm... specific presentation... had to sign an NDA then?
-
#782 by Star One on 21 Sep, 2016 15:16
-
....... and at least one video has to be embargoed until after a paper appears in December.....
The public entering that...euhmm... specific presentation... had to sign an NDA then?
So called second generation EM drive. -
#783 by Gilbertdrive on 21 Sep, 2016 15:28
-
The particle accelerator comments are just completely confusing cause and effect. Accelerators are designed to use charged particles, because we need some way to push on them while they are in a vacuum tube. The best way to do this is via electric and magnetic forces, but that doesn't work on neutral particles. As a result we inject (still slow moving) ions into the accelerator to begin with.
...
The 20-30% c limit I used, just comes from the fact that in accelerators and in nature, detectable atoms exceeding this range seem to be fully ionized bare nuclei. Mostly protons and alpha particles in nature and up to gold and lead nuclei in accelerators.
...
We are moving to 90% of C from billion light years distant galaxies. So, a speed higher than 30% of C is not a problem if it is relatively to a distant body. If it is a problem, it is locally.
Particles in accelerators on earth are also submitted to an important proper acceleration, so it may the important proper acceleration that causes the ionization.
We can not assert that an interplanetary ship in our galaxy would be limited to 30% of C. We have no evidence for that in standard physics.
Saying this means that atoms in space would randomly ionize themselves just because they are moving fast relative to something else is just bad logic. According to everything we know, the only way we would be limited in speed relative to anything (local or distant) is by collisions with slower moving particles. (Assuming we continue having means to accelerate) Space is pretty empty, so > 90% c should be fine.
I agree. 90% of C is fine... but a micrometeorite of 1g would be enough to destroy the ship.
-
#784 by Flyby on 21 Sep, 2016 15:29
-
Nah, I think HMXHMX was referring to the presentation of Paul March, scheduled to be published in December.......... and at least one video has to be embargoed until after a paper appears in December.....
The public entering that...euhmm... specific presentation... had to sign an NDA then?
So called second generation EM drive. -
#785 by Star One on 21 Sep, 2016 15:33
-
Nah, I think HMXHMX was referring to the presentation of Paul March, scheduled to be published in December.......... and at least one video has to be embargoed until after a paper appears in December.....
The public entering that...euhmm... specific presentation... had to sign an NDA then?
So called second generation EM drive.
Out of interest has a so called second generation EM drive ever been shown in public? -
#786 by Gilbertdrive on 21 Sep, 2016 15:37
-
Doesn't Shawyer himself believe the EM drive maxs out somewhere around 30% of C & that it is not capable of truly relativistic speeds? That it doesn't possess infinite acceleration.
Shawyer assumes at least 0.67C.
http://www.sciencedirect.com/science/article/pii/S0094576515002726?np=y
Anyway, this subject send us back to the problem of Kinetic Energy.
1 :If the Emdrive gives constant thrust for constant acceleration, it acts as a free energy device, and violates CoE
2 : If the emdrive does not violate CoE, the Emdrive needs to give a thrust that decrease when the Kinetic Energy increases in a "still to define" referential. This referential for Kinetic Energy needs new physics. For example interaction of the drive with distant masses, with the Hubble horizon, with an aether, etc. There are many ideas that can give us potential referentials for Kinetic Energy, but they all need new physics.
Shawyer indicates that the thrust decreases when his ill defined Kinetic energy increases, but he does not take it into account in his peer-reviewed paper.
The relativist Kinetic Energy of a 10 ton spaceship at 0,67C in an earth referential would be
(10000*(299792458)^2)/sqrt((1-((299792458*0,67)^2)/(299792458^2))))-(10000*(299792458)^2)= 3.1191599e+20 joules.
The Energy provided to the emdrive by the 200kwe nuclear Power plant during the 10 years of operation would be :
200000*3600*24*365,25*10=6.311*10^13 Joules
If Shawyer had taken into account an earth referential for Kinetic Energy, the speed would have only been (I use classic kinetic Energy since we are far from relativist effect and I am lazy)
sqrt(2*6,311*10^13/10000)= 112347 m/s
A little more than 112 km/s IT makes only 0.00037C.
It is not the same order of magnitude !
Of course, I do not pretend that Earth referential has something special, it is just for giving an idea of how much there is not only a problem of pushing against nothing, but also a problem of Energy.
It would be great if the Emdrive was a way of using gravity of other masses. Directed correctly, it would steal kinetic energy to other corpses, as probes do with the flybys. In this way, no need for the ship to provide the Energy. -
#787 by HMXHMX on 21 Sep, 2016 15:43
-
....... and at least one video has to be embargoed until after a paper appears in December.....
The public entering that...euhmm... specific presentation... had to sign an NDA then?
No "public" here, only academics who observe normal embargoe ethical rules. So no NDA. -
#788 by Bob012345 on 21 Sep, 2016 17:12
-
The problem with Shawyer is that, rather than giving no explanation, he gives a mathematically false explanation. As he is not a theoretical scientist, but an Engineer, since he found a formula that provides him the amount of thrust that he had mesured, he seems happy. I think many skeptics would feel more confortable if Shawyer was giving his results as an experimental result, with no false solution.
If no one really knows how the EmDrive really works then how can it be asserted that any solution is 'false'?
If the math is incorrect.
Shawyer would have been better off just publishing the data.
Please point me to a post or page where the math is shown to be incorrect. I've seen that charge used often but it's not always as black and white as it sounds. Sometimes it's the logical or scientific argument that's in dispute rather than actual math. Thanks. -
#789 by Chrochne on 21 Sep, 2016 17:43
-
Alright ladies and gentlemen,
SSI posted first message. It is short, but according to them we should expect A LOT more information to come. As you can see they also posted two links to the articles that sound quite positive for the future of EmDrive.
http://ssi.org/ssi-woodward-propulsion-conference/
-
#790 by tchernik on 21 Sep, 2016 17:57
-
Alright ladies and gentlemen,
SSI posted first message. It is short, but according to them we should expect A LOT more information to come. As you can see they also posted two links to the articles that sound quite positive for the future of EmDrive.
http://ssi.org/ssi-woodward-propulsion-conference/
Funny how the next generation of enabling efforts similar to the Breakthrough Propulsion Project are so pragmatic in their approaches, instead of gathering just theoretical possibilities.
Heidi Fearn, James Woodward, Paul March, Martin Tajmar, Dr. Rodal et al are bringing most of them experimental results. I imagine that's the very reason this conference exists. Results that need discussion.
I wouldn't have believed such a thing a few years back. Let's remember we are talking about experiments looking for measurable and usable forces and effects, the least of them revolutionary in its implications.
But there it is. -
#791 by giulioprisco on 21 Sep, 2016 18:00
-
Alright ladies and gentlemen,
SSI posted first message. It is short, but according to them we should expect A LOT more information to come. As you can see they also posted two links to the articles that sound quite positive for the future of EmDrive.
http://ssi.org/ssi-woodward-propulsion-conference/
I wrote the second article, based mostly on info gathered here. "Positive" in the sense that I hope EmDrive works, in which case I would be very interested in theoretical explanations of how it works, sure. I would also love to see the faces of the smug militant skeptics when they are forced to admit that EmDrive works. But of course we must wait for solid experimental data and sensible theoretical explanations. -
#792 by Bob012345 on 21 Sep, 2016 18:38
-
Doesn't Shawyer himself believe the EM drive maxs out somewhere around 30% of C & that it is not capable of truly relativistic speeds? That it doesn't possess infinite acceleration.
Shawyer assumes at least 0.67C.
http://www.sciencedirect.com/science/article/pii/S0094576515002726?np=y
Anyway, this subject send us back to the problem of Kinetic Energy.
1 :If the Emdrive gives constant thrust for constant acceleration, it acts as a free energy device, and violates CoE
2 : If the emdrive does not violate CoE, the Emdrive needs to give a thrust that decrease when the Kinetic Energy increases in a "still to define" referential. This referential for Kinetic Energy needs new physics. For example interaction of the drive with distant masses, with the Hubble horizon, with an aether, etc. There are many ideas that can give us potential referentials for Kinetic Energy, but they all need new physics.
Shawyer indicates that the thrust decreases when his ill defined Kinetic energy increases, but he does not take it into account in his peer-reviewed paper.
The relativist Kinetic Energy of a 10 ton spaceship at 0,67C in an earth referential would be
(10000*(299792458)^2)/sqrt((1-((299792458*0,67)^2)/(299792458^2))))-(10000*(299792458)^2)= 3.1191599e+20 joules.
The Energy provided to the emdrive by the 200kwe nuclear Power plant during the 10 years of operation would be :
200000*3600*24*365,25*10=6.311*10^13 Joules
If Shawyer had taken into account an earth referential for Kinetic Energy, the speed would have only been (I use classic kinetic Energy since we are far from relativist effect and I am lazy)
sqrt(2*6,311*10^13/10000)= 112347 m/s
A little more than 112 km/s IT makes only 0.00037C.
It is not the same order of magnitude !
Of course, I do not pretend that Earth referential has something special, it is just for giving an idea of how much there is not only a problem of pushing against nothing, but also a problem of Energy.
It would be great if the Emdrive was a way of using gravity of other masses. Directed correctly, it would steal kinetic energy to other corpses, as probes do with the flybys. In this way, no need for the ship to provide the Energy.
As best I understand, Shawyer says conservation of energy limits the acceleration but once you achieve a certain allowed acceleration, you can go till relativity limits the speed or your onboard energy source quits. In the case of his interstellar probe design, the probe accelerates at 0.1g or less and gets to 0.67c as it crosses the Centauri system in about ten years mission time. It did not seem 0.67c was the limiting velocity of the probe wrt earth frame. It would keep going till the nuclear reactor winds down and or the well known relativistic effect that a constant acceleration in the probe frame would gradually diminish wrt earth frame due to relativistic dynamics which would apply to any source of acceleration.
Regarding the kinetic energy conundrum mentioned, I find the use of the Work Energy Theorem helps. In any observer frame, a constant force provides a constant acceleration (non relativistically for now but the theorem works relativistically too). The force integrated over the distance is always equal to the kinetic energy change and that works for any observer. There are two powers to consider. One, the power creating the force onboard the ship or probe, and then the mechanical power required by the work energy theorem. It is the second, the mechanical power integrated over time that equates to the kinetic energy change, not the input power to create the constant force. That's how Shawyer and Fetta compute things I believe. The two powers are independent. There is only an energy conundrum when one tries to equate the onboard input electrical power integrated over time to the kinetic energy change. The only case where this works is for pure photon rockets or beamed propulsion in which the total input energy is always greater than the change in kinetic energy. As a pure photonic rocket starting from rest in some frame approaches c, the input energy approaches the kinetic energy. A stretch of photon recycling over part of the trip would also lead to a false energy conundrum.
Both Shawyer and the Cannae Deep Space Probe designs exhibit this apparent kinetic energy conundrum and both are false problems in my view. I know many will disagree and that's fine. I've personally been on both sides of this issue. I wrote several emails to Shawyer myself pointing out his 'error'. Thankfully, he graciously ignored my emails. Now, I think Shawyer and Fetta are correct. -
#793 by Tellmeagain on 21 Sep, 2016 18:46
-
Funny how the next generation of enabling efforts similar to the Breakthrough Propulsion Project are so pragmatic in their approaches, instead of gathering just theoretical possibilities.
Heidi Fearn, James Woodward, Paul March, Martin Tajmar, Dr. Rodal et al are bringing most of them experimental results. I imagine that's the very reason this conference exists. Results that need discussion.
I wouldn't have believed such a thing a few years back. Let's remember we are talking about experiments looking for measurable and usable forces and effects, the least of them revolutionary in its implications.
But there it is.
It is a pity that only optimists are invited. A meeting with only optimists is good at creating unrealistic positive atmosphere people see recently. I also think the theoretic works are premature before the effect is established. -
#794 by Star One on 21 Sep, 2016 18:46
-
How does the exchange work between here so to speak and distant objects beyond the cosmological horizon? Why is it always with objects beyond the cosmological horizon in the universe? As isn't the cosmological horizon the maximum distance you can retrieve information from. Are we saying it works because it is beyond the informational limits.
-
#795 by Chrochne on 21 Sep, 2016 19:14
-
Funny how the next generation of enabling efforts similar to the Breakthrough Propulsion Project are so pragmatic in their approaches, instead of gathering just theoretical possibilities.
Heidi Fearn, James Woodward, Paul March, Martin Tajmar, Dr. Rodal et al are bringing most of them experimental results. I imagine that's the very reason this conference exists. Results that need discussion.
I wouldn't have believed such a thing a few years back. Let's remember we are talking about experiments looking for measurable and usable forces and effects, the least of them revolutionary in its implications.
But there it is.
It is a pity that only optimists are invited. A meeting with only optimists is good at creating unrealistic positive atmosphere people see recently. I also think the theoretic works are premature before the effect is established.
You are of course right. But I think it is also driven by the fact that those people very likely reached the information we did not yet see. Of course after each time of excitement comes the hard part of realizing the truth and it is not always so shiny.
But on other hand an army of people were and still are waiting for news on EmDrive for more than one year. So I guess it is natural to be excited now.
Edit: I just realized - I would not exactly call them all optimists. Dr. Rodal is quite pessimist on the issue and I dare to say he is in the camp of critics of the EmDrive. It was only just recently that he is more optimistic on the issue. I really wonder why :-). -
#796 by Star One on 21 Sep, 2016 19:33
-
Funny how the next generation of enabling efforts similar to the Breakthrough Propulsion Project are so pragmatic in their approaches, instead of gathering just theoretical possibilities.
Heidi Fearn, James Woodward, Paul March, Martin Tajmar, Dr. Rodal et al are bringing most of them experimental results. I imagine that's the very reason this conference exists. Results that need discussion.
I wouldn't have believed such a thing a few years back. Let's remember we are talking about experiments looking for measurable and usable forces and effects, the least of them revolutionary in its implications.
But there it is.
It is a pity that only optimists are invited. A meeting with only optimists is good at creating unrealistic positive atmosphere people see recently. I also think the theoretic works are premature before the effect is established.
You are of course right. But I think it is also driven by the fact that those people very likely reached the information we did not yet see. Of course after each time of excitement comes the hard part of realizing the truth and it is not always so shiny.
But on other hand an army of people were and still are waiting for news on EmDrive for more than one year. So I guess it is natural to be excited now.
Edit: I just realized - I would not exactly call them all optimists. Dr. Rodal is quite pessimist on the issue and I dare to say he is in the camp of critics of the EmDrive. It was only just recently that he is more optimistic on the issue. I really wonder why :-).
Only one thing could account for his change of mind and that is experimental results. -
#797 by Gilbertdrive on 21 Sep, 2016 19:34
-
As best I understand, Shawyer says conservation of energy limits the acceleration but once you achieve a certain allowed acceleration, you can go till relativity limits the speed or your onboard energy source quits. In the case of his interstellar probe design, the probe accelerates at 0.1g or less and gets to 0.67c as it crosses the Centauri system in about ten years mission time. It did not seem 0.67c was the limiting velocity of the probe wrt earth frame. It would keep going till the nuclear reactor winds down and or the well known relativistic effect that a constant acceleration in the probe frame would gradually diminish wrt earth frame due to relativistic dynamics which would apply to any source of acceleration.
Regarding the kinetic energy conundrum mentioned, I find the use of the Work Energy Theorem helps. In any observer frame, a constant force provides a constant acceleration (non relativistically for now but the theorem works relativistically too). The force integrated over the distance is always equal to the kinetic energy change and that works for any observer. There are two powers to consider. One, the power creating the force onboard the ship or probe, and then the mechanical power required by the work energy theorem. It is the second, the mechanical power integrated over time that equates to the kinetic energy change, not the input power to create the constant force. That's how Shawyer and Fetta compute things I believe. The two powers are independent. There is only an energy conundrum when one tries to equate the onboard input electrical power integrated over time to the kinetic energy change. The only case where this works is for pure photon rockets or beamed propulsion in which the total input energy is always greater than the change in kinetic energy. As a pure photonic rocket starting from rest in some frame approaches c, the input energy approaches the kinetic energy. A stretch of photon recycling over part of the trip would also lead to a false energy conundrum.
Both Shawyer and the Cannae Deep Space Probe designs exhibit this apparent kinetic energy conundrum and both are false problems in my view. I know many will disagree and that's fine. I've personally been on both sides of this issue. I wrote several emails to Shawyer myself pointing out his 'error'. Thankfully, he graciously ignored my emails. Now, I think Shawyer and Fetta are correct.
I agree about the fact that 0.67C is not a limit. That is why I have written "at least" My position is that there is no speed limit other than C, no speed that break apart everything.
Do you realize that if you assume constant acceleration for constant electric power, and no energy stolen to something else (kinetic energy stolen to distant masses, or energy stolen to the quantum vacuum, or any other mechanism to take energy to something external to the ship) you get a free energy device ?
You can use your spaceship going to Alpha century and coming back, it arrives more Kinetic Energy that it has spent of eletrical power ?
Just to be sure that it is clear about that.
Also, it can become a terrible weapon. The 10 tons spaceship coming back on earth at 0.67C would have more energy than several millions of Hiroshima bombs.
-
#798 by Tellmeagain on 21 Sep, 2016 19:38
-
You are of course right. But I think it is also driven by the fact that those people very likely reached the information we did not yet see. Of course after each time of excitement comes the hard part of realizing the truth and it is not always so shiny.
But on other hand an army of people were and still are waiting for news on EmDrive for more than one year. So I guess it is natural to be excited now.
Edit: I just realized - I would not exactly call them all optimists. Dr. Rodal is quite pessimist on the issue and I dare to say he is in the camp of critics of the EmDrive. It was only just recently that he is more optimistic on the issue. I really wonder why :-).
I can only speculate that he did not spot problems (or was told so by others) from Paul March's December paper. -
#799 by tchernik on 21 Sep, 2016 20:27
-
Funny how the next generation of enabling efforts similar to the Breakthrough Propulsion Project are so pragmatic in their approaches, instead of gathering just theoretical possibilities.
Heidi Fearn, James Woodward, Paul March, Martin Tajmar, Dr. Rodal et al are bringing most of them experimental results. I imagine that's the very reason this conference exists. Results that need discussion.
I wouldn't have believed such a thing a few years back. Let's remember we are talking about experiments looking for measurable and usable forces and effects, the least of them revolutionary in its implications.
But there it is.
It is a pity that only optimists are invited. A meeting with only optimists is good at creating unrealistic positive atmosphere people see recently. I also think the theoretic works are premature before the effect is established.
They can be optimistic about their data, but I'm not sure they are optimistic about each other's data and theories. Let's remember not all of their theories can be right, and that in the worst case, probably none of them are.
Probably they are trying the waters and looking for feedback (criticism or cross-pollinating ideas) from people in similar situations and that are about to release something somewhat controversial upon the world.
Because this must reach the wide world eventually, where not everybody is friendly or even, willing to entertain the idea that these phenomena even exist.
