tag:blogger.com,1999:blog-4637778157419388168.post2382778000598121830..comments2024-03-21T09:01:08.175-07:00Comments on Physics with an edge: MiHsC & emdrive: a new approach.Mike McCullochhttp://www.blogger.com/profile/00985573443686082382noreply@blogger.comBlogger27125tag:blogger.com,1999:blog-4637778157419388168.post-24552202095740730012015-06-21T00:59:57.298-07:002015-06-21T00:59:57.298-07:00You're right: an average is not a good physica...You're right: an average is not a good physical parameter. I'll have to think it over. Thanks for the comments.Mike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-47562883538680699722015-06-20T14:28:54.287-07:002015-06-20T14:28:54.287-07:00Yes, I agree with that - but on the other hand, in...Yes, I agree with that - but on the other hand, inertia is only present/effective while acceleration is occurring, so MiHsC is only significant during that time. Once the photon has bounced and is travelling along the cavity, surely it's no longer affected by Unruh waves?Anonymoushttps://www.blogger.com/profile/08088810298471205858noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-13253606447436544702015-06-20T14:09:40.091-07:002015-06-20T14:09:40.091-07:00I'm considering your point, but in fact I see ...I'm considering your point, but in fact I see it the other way. The average over a single end-end pass is not arbitrary and is well defined. What would be arbitrary is calculating the acceleration during the reflection process itself. What is that time? How could you ever decide what it is? So I regard what I've done as less arbitrary..Mike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-43438295950726773612015-06-20T12:47:35.814-07:002015-06-20T12:47:35.814-07:00Hi Mike,
Surely the Unruh waves are emitted only ...Hi Mike, <br />Surely the Unruh waves are emitted only during the acceleration period? It then doesn't make sense to average the acceleration over an arbitrary length of time.Anonymoushttps://www.blogger.com/profile/08088810298471205858noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-69799323102826664102015-06-20T09:56:02.223-07:002015-06-20T09:56:02.223-07:00Good point. This is the average acceleration over ...Good point. This is the average acceleration over time..so that is an assumption.Mike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-23549373595419132822015-06-20T08:30:14.934-07:002015-06-20T08:30:14.934-07:00Hi Mike, sorry to keep going back on this topic! I...Hi Mike, sorry to keep going back on this topic! I'm unsure why the time component of the acceleration is (l/c). This suggests the photon accelerates along the length of the cavity, but I thought it the acceleration would be effectively instantaneous because the photon just bounces off the metal.Anonymoushttps://www.blogger.com/profile/08088810298471205858noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-49116629845083771172015-06-18T13:15:00.287-07:002015-06-18T13:15:00.287-07:00Why should it matter that it resonate at a particu...Why should it matter that it resonate at a particular frequency? Is it just to have enough photons bouncing back and forth to transfer momentum from the shift in inertial mass? If so, wouldn't it just be the amount of photons in the cavity? Is it somehow the resonation that makes the cone opaque to Unruh radiation, forcing more to fit inside the larger end?Shawn McKenziehttps://www.blogger.com/profile/05616086087522659191noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-82521740302041883032015-06-18T10:42:40.400-07:002015-06-18T10:42:40.400-07:00Photon acceleration, if we can imagine such a thin...Photon acceleration, if we can imagine such a thing, is a=dv/dt. So imagine a photon in the cavity going at speed c rightwards then bouncing back from the end to go at speed c leftward. Then a=dv/dt=2c/(l/c)=2c^2/l. The wavelength of Unruh radiation is lambda=8c^2/a=8c^2/(2c^2/l)=4l.Mike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-13261974437932171362015-06-18T10:02:09.184-07:002015-06-18T10:02:09.184-07:00Hi Mike,
Why is the Unruh wavelength dependent on ...Hi Mike,<br />Why is the Unruh wavelength dependent on the cavity length? Isn't it dependent on the magnitude of the acceleration, which in the case of bouncing photons simply proportional to C?Anonymoushttps://www.blogger.com/profile/08088810298471205858noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-21111904463836461712015-06-18T05:49:58.478-07:002015-06-18T05:49:58.478-07:00There are two wavelengths here that are probably r...There are two wavelengths here that are probably related. The wavelength of the EM radiation, which needs to resonate in the cavity. Then the wavelength of the Unruh waves produced by the back and forth photon accelerations, that MiHsC assumes causes their inertia. The Unruh wavelength is 4*l, where l is cavity length.<br /><br />The baffles should hopefully not interfere with the end-end wave propagation but should disallow lateral waves, so their spacing should be a non-multiple of the wavelength. Yes, concentric rings might do it, dependson their spacing.<br /><br />The curve of the end plates should be concentric, so curved the same way, so the side view looks like a slice out of an annulus. This is so that l is the same for all end-to-end photons & so the Unruh waves are more focused on one wavelength (4l) which can then be tuned to the size of the wide end.Mike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-86103686670956489102015-06-18T04:40:46.460-07:002015-06-18T04:40:46.460-07:00What is the relationship between the axial length ...What is the relationship between the axial length of the cavity (l) and the wavelength? The data in your post "MiHsC vs EmDrive data: 3d" doesn't show a clear relationship between the two, e.g. a cavity length that is a multiple of some fraction of the wavelength. I was wondering if there would be a way to calculate the optimal cavity for a given wavelength.<br /><br />As for baffles, are you suggesting something like concentric rings protruding from the surface of the small end?<br /><br />Also, would a hemispherical arrangement of end-reflectors (Concave wide end, planar small end) also work? https://en.wikipedia.org/wiki/File:Optical-cavity1.pngAnonymoushttps://www.blogger.com/profile/01747040562985657137noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-58141673456569401822015-06-18T04:36:24.037-07:002015-06-18T04:36:24.037-07:00This comment has been removed by the author.Anonymoushttps://www.blogger.com/profile/01747040562985657137noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-41458123995750391362015-06-18T02:17:47.187-07:002015-06-18T02:17:47.187-07:00MiHsC implies the following: The ideal is not a sh...MiHsC implies the following: The ideal is not a sharp cone, as my simplified 1-d equation implied (because there's no end-end bouncing). The ideal is the usual truncated cone with two flat (or ideally curved facing) surfaces. If using flat surfaces the width of the big end (wb) should be longer than the axial length of the cavity (l) so that the Unruh waves set up by the photons bouncing between the ends (some taking a diagonal route longer than l) 'fit' at the wide end, but not at the narrow. I can give a formula for wb=fn(l,ws) It could be set up with baffles at the short end to further break up waves there. It could be set up 'short' so that l~ws (width of the small end) instead, so the Unruh wavelengths fit better at the short end and deliberately de-harmonise the wider width, then there may be a smaller reverse thrust, but this is likely to be difficult to achieve (note: this is all approximate since I don't have a full 3-d model).Mike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-23598928662265115892015-06-17T06:15:30.759-07:002015-06-17T06:15:30.759-07:00So, what would be the optimal cavity shape and dim...So, what would be the optimal cavity shape and dimensions, according to your interpretation?Anonymoushttps://www.blogger.com/profile/01747040562985657137noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-27495496540544895542015-06-08T03:38:52.745-07:002015-06-08T03:38:52.745-07:00Thanks Martin. I've followed them on hackaday....Thanks Martin. I've followed them on hackaday..Mike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-2265357608939840552015-06-07T02:10:54.881-07:002015-06-07T02:10:54.881-07:00Hi Mike,
There's a project on hackaday.io tha...Hi Mike,<br /><br />There's a project on hackaday.io that attempts to build a smaller version of the emdrive (https://hackaday.io/project/5596-em-drive). They should be doing test runs next this week.Anonymoushttps://www.blogger.com/profile/12086925473124132817noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-63125314934821110552015-06-02T04:35:23.884-07:002015-06-02T04:35:23.884-07:00Eirinn: Yes, I do mean the Unruh frequency. The Un...Eirinn: Yes, I do mean the Unruh frequency. The Unruh wavelengths are not dependent on the microwave frequency (I'm assuming that the acceleration that produces the Unruh radiation comes from the photons bouncing back and forth in the cavity), but it seems resonant microwaves are crucial to the effect so their wavelength should be tuned to the cavity. The Unruh waves are similar to the size of the box, and this falls out of the maths, so any sized box will do, so long as the microwaves resonate.Mike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-4177142441366940892015-06-02T00:14:58.813-07:002015-06-02T00:14:58.813-07:00Hi Mike, when you say that MiHsC is very sensitive...Hi Mike, when you say that MiHsC is very sensitive to the frequency, you are talking about the Unruh waves rather than the microwaves, correct? From your paper it appears that Unruh wavelengths are not dependent on the microwave wavelength. In that case, we can't tune the Unruh freqencies to the box, but rather there is an optimimum size for the big and small diameters.Anonymoushttps://www.blogger.com/profile/08088810298471205858noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-41344606749354246292015-06-01T23:05:47.624-07:002015-06-01T23:05:47.624-07:00Mike, you might want to take a look at 'Notsos...Mike, you might want to take a look at 'Notsosureofit's' latest effort - a chart that seems to be a bit of a breakthrough. Has to do with accelerating photons. Rodal and others seem to think this is critical.Anonymoushttps://www.blogger.com/profile/06388738042629653874noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-33893691955503524552015-06-01T14:24:52.980-07:002015-06-01T14:24:52.980-07:00The Brady report shows these cases where a lower Q...The Brady report shows these cases where a lower Q produced a higher force. The force more than doubled with the Q at 40% of the high value:<br /><br />page 18<br />Table 2. Tapered Cavity Testing: Summary of Results<br /><br />Mode Frequency(MHz) , Q Input Power (W) Peak Thrust (μN) Number of Test Runs<br />TM211 1932.6 7,320 16.9 116.0 5<br />TM211 1936.7 18,100 16.7 54.1 2<br /><br />Same mode, (practically) same frequency and power :<br /><br />Notice that at a Q only 2/5 of the higher one (7320 instead of 18100) resulted in greater than twice as high a thrust force (116 instead of 54).<br /><br />This experiment is important, as it shows that it is unwarranted to assume that there is monotonic one-to-one functional relationship for measured<br />http://forum.nasaspaceflight.com/index.php?topic=37642.msg1382932#msg1382932Anonymoushttps://www.blogger.com/profile/11867935317921430944noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-30651101748937985422015-06-01T14:19:33.222-07:002015-06-01T14:19:33.222-07:00Thank you for your comments. Indeed, the effect of...Thank you for your comments. Indeed, the effect of MiHsC should be very sensitive to the frequency. If the Unruh waves are too long they won't fit anywhere along the cavity so: less or no thrust, and for example if they fit better at the narrow end there'll be a reverse thrust, as has been seen. I discuss this a little bit here:<br /><br />http://physicsfromtheedge.blogspot.co.uk/2015/03/one-wave-approximation-of-mihsc.htmlMike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-59616809981552153962015-06-01T13:53:36.981-07:002015-06-01T13:53:36.981-07:00I'm sure you have seen the conversation on NAS...I'm sure you have seen the conversation on NASA's blog site but little or no thrust is made when the RF input into the cavity is at peak Q but a little off and it looks like it's a lower frequency.Anonymoushttps://www.blogger.com/profile/11867935317921430944noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-28217271788330458042015-06-01T11:51:57.119-07:002015-06-01T11:51:57.119-07:00Hm. I'm already tending away from this solid-s...Hm. I'm already tending away from this solid-state view because the acceleration of the cavity is unlikely to be large enough to create Unruh waves short enough to interact with the cavity. The schematic is still useful as a visualisation, but for photons.Mike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-4266559951363628832015-06-01T02:04:52.438-07:002015-06-01T02:04:52.438-07:00Eirinn: very good point. Before answering it I nee...Eirinn: very good point. Before answering it I need to work out the full derivation, which I'm struggling through now..Mike McCullochhttps://www.blogger.com/profile/00985573443686082382noreply@blogger.comtag:blogger.com,1999:blog-4637778157419388168.post-65023252733871333812015-06-01T00:01:18.419-07:002015-06-01T00:01:18.419-07:00Hi Mike,
If the photons are simply a source of v...Hi Mike, <br /><br />If the photons are simply a source of vibration, then would we also see an effect from vibrating a metal cavity with sound waves? Anonymoushttps://www.blogger.com/profile/08088810298471205858noreply@blogger.com