B MEGA Drive: Jim Woodward's Propulsion System, Real or Fiction?

[Randy Subers]

TL;DR Summary

Is MEGA drive realistic?

Is Jim Woodward's MEGA drive (https://www.nasa.gov/directorates/s...for_In_Space_Propulsion_Interstellar_Mission/) likely to be for real? It seems to violate conservation of momentum. If it does how does it get away with it?

 

[PeterDonis]

Is Jim Woodward's MAGA drive (https://www.nasa.gov/directorates/s...for_In_Space_Propulsion_Interstellar_Mission/) likely to be for real?

Although the NASA page you link to claims this work is based on peer-reviewed science, there are no links to actual peer-reviewed papers in it. So there is no real basis for discussion there.

The Wikipedia page for James Woodward does have some links to papers:

https://en.wikipedia.org/wiki/James_F._Woodward

The first one (ref. 2 in the article, the 1990 paper) appears to be claiming that the effect on which the MEGA drive is based is either the same as, or similar to, the Nordtvedt effect. Unfortunately, there are very tight experimental limits on that effect, as shown in the references in this article:

https://en.wikipedia.org/wiki/Nordtvedt_effect

I have only skimmed the papers so far, but my general sense is that claims are made about GR which are based on misconceptions and are not actually correct theoretically.

That said, it is perfectly possible that experimental effects exist for which we don't have a good theoretical understanding; that has happened many times in the history of physics. However, looking through the long PDF linked from the NASA article (which is not a peer-reviewed paper, it's a report to NASA from the grant recipient), it seems to me that the effects observed so far are tiny and quite possibly due to experimental error. A real demonstration would have to involve a clear production of an easily measurable force under conditions where there is no possible source of that force based on present-day understanding (no rocket, no laser beam, no wind, etc.). It's not clear if or when NASA will be trying to make such a demonstration for this proposal.

It seems to violate conservation of momentum.

Momentum can be stored in fields, and the basic hypothesis on which this proposal is based appears to be that there is some kind of scalar field associated with gravity (the general term for such theories of gravity is "scalar-tensor theories"), which could serve as a source of momentum (just as electromagnetic fields can store momentum and impart it to charged particles). That's not to say that that hypothesis is true, just that it is not necessarily open to such a simple objection.

 

[bob012345]

Momentum can be stored in fields

Do you mean different than the momentum of light $p = E/c$ ? Thanks.

 

[PeterDonis]

Do you mean different than the momentum of light $p = E/c$ ? Thanks.

That's one example of momentum stored in fields (the EM field, in this case), but not the only possible example. Any field can store momentum.

 

[bob012345]

That's one example of momentum stored in fields (the EM field, in this case), but not the only possible example. Any field can store momentum

As far as you know will the structure always be the same as for EM fields where the momentum is energy over speed of propagation of the field? If so and the speed of propagation of some other than EM field is $c$, it seems to me that it would be no more efficient than a photon rocket?

 

[PeterDonis]

As far as you know will the structure always be the same as for EM fields where the momentum is energy over speed of propagation of the field?

This is true for any massless field. I believe the scalar field proposed in scalar-tensor theories of gravity is massless.

If so and the speed of propagation of some other than EM field is $c$, it seems to me that it would be no more efficient than a photon rocket?

The field proposed in scalar-tensor theories of gravity is not "some other EM field". The EM field is a vector field, not a scalar field.

As for "efficiency", the proposed mechanism (if it is even valid) is not a rocket and you cannot assume that the "efficiency" will work the same as a rocket.

 

[bob012345]

What I wrote was not some other EM field but some other than EM field by which I meant not an EM field. I don't have much familiarity with field momentum beyond the EM field which is why I related it to that. Sorry for any confusion.

 

[bob012345]

Summary:: Is MEGA drive realistic?

Is Jim Woodward's MEGA drive (https://www.nasa.gov/directorates/s...for_In_Space_Propulsion_Interstellar_Mission/) likely to be for real? It seems to violate conservation of momentum. If it does how does it get away with it?

There are a lot of people associated with this project and there is a multi-year history of papers, conferences and articles. In the end it all boils down to accurate data that can be replicated. Woodward discusses the latest experiments and changes to the design and experimental procedure here;

https://www.intechopen.com/online-first/keeping-the-dream-alive-is-propellant-less-propulsion-possible

Near the end Woodward says recent results are much better than past results and that two replications are in process. Is it real? Only time will tell.

 

[PeterDonis]

What I wrote was not some other EM field but some other than EM field by which I meant not an EM field.

Yes, I went back and re-read your post and I see I misread the wording before. Sorry about that.