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NASA's EmDrive actually works

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  • NASA's EmDrive actually works

    It is basically the equivalent of being on a sailboat with a fan blowing into the sail and having it actually work.

    It bounces microwaves around in a closed chamber and produces propulsion.

    http://www.nasaspaceflight.com/2015/...stic-em-drive/
    A group at NASA’s Johnson Space Center has successfully tested an electromagnetic (EM) propulsion drive in a vacuum – a major breakthrough for a multi-year international effort comprising several competing research teams. Thrust measurements of the EM Drive defy classical physics’ expectations that such a closed (microwave) cavity should be unusable for space propulsion because of the law of conservation of momentum.

    2015-04-19-005958-350x236.jpg


  • #2
    Any practical earthbound uses?
    That's what
    - She

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    • #3
      Originally posted by Bill the Cat View Post
      Any practical earthbound uses?
      I don't think so, the thrust build up would be very slow and I believe it has to be in a vacuum to work. But in space it is practically free propulsion and doesn't use any fuel so there is no limit to it's ultimate speed (except physics, which they are working on too with their warp drive)

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      • #4


        Mythbusters got there first...
        Last edited by Raphael; 05-01-2015, 12:59 AM. Reason: fixed embedding

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        • #5
          I'm still highly dubious that this thing actually works. If it does, great, we'll celebrate a new revolution in physcs with the invention of an inertialess drive. But before we get there, I want to see this reconfirmed.

          If for instance one side of the device got just slightly warmer than the other side this could lead to a thrust being detected, basically because the infrared heat emission of one side would have a higher net momentum than the other side. There's not much documentation here to establish if this has occurred, or not, except for some mentions of temperature probes.
          Last edited by Leonhard; 05-01-2015, 06:17 AM.

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          • #6
            Did some back of the envelope calculations. It depends a lot of emmisivity of the surface and the size of the device, but in order to get 50mN for a copper bodied device, with with a size of 1/10 square meters, you'd need a temperature difference between one side and the other of 800 degrees, making one side glow orange hot. So this isn't a possible mode of explanation for their result.

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            • #7
              Yeah, but it sure sounds suspiciously like a free lunch.

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              • #8
                Originally posted by Sparko View Post
                It is basically the equivalent of being on a sailboat with a fan blowing into the sail and having it actually work.

                It bounces microwaves around in a closed chamber and produces propulsion.

                http://www.nasaspaceflight.com/2015/...stic-em-drive/
                A group at NASA’s Johnson Space Center has successfully tested an electromagnetic (EM) propulsion drive in a vacuum – a major breakthrough for a multi-year international effort comprising several competing research teams. Thrust measurements of the EM Drive defy classical physics’ expectations that such a closed (microwave) cavity should be unusable for space propulsion because of the law of conservation of momentum.

                [ATTACH=CONFIG]6106[/ATTACH]
                Whatever skepticism you might have, this is real science, real experiments. They are looking for classical explanations, but so far it has met all objections and does appear to be producing thrust w/o propellant. They need to get a working model up to the space station that produces a newton or so of thrust in the lab (achievable with <3kw it appears), turn it on and see if it actually does anything.



                Jim
                He will reply, ‘Truly I tell you, whatever you did not do for one of the least of these, you did not do for me."

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                • #9
                  Originally posted by oxmixmudd View Post
                  Whatever skepticism you might have, this is real science, real experiments. They are looking for classical explanations, but so far it has met all objections and does appear to be producing thrust w/o propellant. They need to get a working model up to the space station that produces a newton or so of thrust in the lab (achievable with <3kw it appears), turn it on and see if it actually does anything.



                  Jim
                  And if it does work, it is evidence that we are living in the matrix or some cartoon video game world.

                  next up! Quantum tunneling wormholes created by painting tunnels on cliffs.

                  wile-e-coyote-tunnel.jpg

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                  • #10
                    Originally posted by Sparko View Post
                    And if it does work, it is evidence that we are living in the matrix or some cartoon video game world.
                    Or that our scientific understanding is ever so slightly less than we think.
                    Micah 6:8 He has told you, O man, what is good; and what does the LORD require of you but to do justice, and to love kindness, and to walk humbly with your God?

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                    • #11
                      In General Relativity, energy/momentum measured in a frame of reference is not generally transformable to another frame, if I understand correctly. The Bianchi identities might be better used rather than energy/momentum, but I am frankly unsure what is conserved in General Relativity that is a generalization of energy/momentum, particularly in an expanding universe.
                      The greater number of laws . . . , the more thieves . . . there will be. ---- Lao-Tzu

                      [T]he truth I’m after and the truth never harmed anyone. What harms us is to persist in self-deceit and ignorance -— Marcus Aurelius, Meditations

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                      • #12
                        Originally posted by Truthseeker View Post
                        In General Relativity, energy/momentum measured in a frame of reference is not generally transformable to another frame
                        The energy-momentum is a four-vector quite easily transformable between frames of reference, and fulfills its invariant under all such transformations.

                        The Bianchi identities might be better used rather than energy/momentum,
                        The Bianchi identity is just the curvature of spacetime, and since in Einstein's General Theory of relativity, this curvature is proportional of the density of energy-momentum, we can easily find one if we have the other. However, using only the Bianchi identity would only be good if we could know the curvature. Since its easier to measure mass and momentum, we use the latter.

                        but I am frankly unsure what is conserved in General Relativity that is a generalization of energy/momentum, particularly in an expanding universe.
                        Energy-momentum is conserved.

                        The EMDrive will either: Turn out not to work, which is most likekly or turn out to work, but not violate conservation of momentum... somehow its expelling something which isn't clear at the moment (I doubt this though).

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                        • #13
                          who knows? maybe it is pushing against the cosmic background microwave radiation or something equally as weird.

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                          • #14
                            Groovy.
                            Last edited by Duragizer; 05-02-2015, 04:48 PM.
                            "When the Western world accepted Christianity, Caesar conquered; and the received text of Western theology was edited by his lawyers…. The brief Galilean vision of humility flickered throughout the ages, uncertainly…. But the deeper idolatry, of the fashioning of God in the image of the Egyptian, Persian, and Roman imperial rulers, was retained. The Church gave unto God the attributes which belonged exclusively to Caesar."

                            — Alfred North Whitehead

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                            • #15
                              Originally posted by Sparko View Post
                              who knows? maybe it is pushing against the cosmic background microwave radiation or something equally as weird.
                              I'm open for most things, right now though I suspect that there's a subtle error in their setup which they haven't detected. My other bet was that it was somehow a photon rocket... if it emits microwaves more in one direction than another, that too would produce net thrust.

                              As for pushing against the CMB, that's not physically impossible, as there's something called photon-photon scattering. However that requires photons with extremely high energies (deep gamma ray photons). So while it could work in principle, it won't work with microwaves.
                              Last edited by Leonhard; 05-02-2015, 06:11 PM.

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