Hard Light Productions Forums
Off-Topic Discussion => General Discussion => Topic started by: Bobboau on May 02, 2015, 12:57:42 am
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http://www.nasaspaceflight.com/2015/04/evaluating-nasas-futuristic-em-drive/
:warp:
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It's been talked about for quite some time. Not only does it work in vacuum, it also produces noticeable results with Warp Field Interferometer - the gizmo dr. White uses for his Alcubierre Drive research. It's one of the more bizzare inventions I've ever seen, the potential implications are incredible. Extraordinary claims require extraordinary evidence, sure, but there you have it. :)
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It's been talked about for quite some time. Not only does it work in vacuum, it also produces noticeable results with Warp Field Interferometer - the gizmo dr. White uses for his Alcubierre Drive research.
The article mentions both the EM Drive working in a vacuum and the Warp Field Interferometer detecting measurable, repeatable results; the two are not linked beyond both being researched by NASA Eagleworks. EDIT: I missed a vital sentence.
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:D
This is really exciting!
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And we still have no idea how the damn thing works. :lol:
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And we still have no idea how the damn thing works. :lol:
Yep. We may have accidentally proven the existence of quantum vacuum virtual plasma before we even figured out how to test if it exists.
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That's assuming this thing's operating principle isn't even more bizzare. From what I've gathered, we might have a sub-light warp drive on our hands. Although it producing force seems to imply something else, it does register quite strongly on White's Warp Field Interferometer. Or maybe "QV virtual plasma noise" and "random warping of ambient spacetime" are two ways of saying the same thing? Wouldn't be the first case of that in physics. Eh, I really of wish my institute had some sort of partnership with NASA. The new particle accelerator we have is nice, but what I wouldn't give to have a chance of working with White's WFI and the EM drive tests... :) There will be some really exciting things happening in there in the near future.
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would be hilarious if we found out that supersaturating an area of space with photons had an effect indistinguishable to negative mass or something equally bizarre.
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If true, that could explain how core collapse of a star leads to supernova explosion. :) But I am pretty sure it is not true. If a few kilowatts (or whatever it is now) is making an experimentally observable effect through such a mechanism, then you'd expect pretty obvious decrease in the gravitational field of stars.
Relativistically, filling space with photons actually increases the gravitational field, because of their momentum.
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yeah, nothing about this thing makes any form of sense. a few kilowatts of power shouldn't be able to do anything unexpected, we'd be seeing lots of other weird things in nature. maybe it could be an effect of very strong standing waves? those don't happen very often in nature, everything about this smells other than the fact that it keeps getting positive results in multiple experiments at multiple labs. the fact this happens to now have a connection with alcubirre drives is just way to ****ing convenient.
I guess we'll see what happens a few months from now.
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If true, that could explain how core collapse of a star leads to supernova explosion. :)
Isn't that explained quite thoroughly by the energy output of the heavy metal fusion resulting from the gravitational collapse? I wasn't aware of there being an unexplained portion requiring an "anti-gravity" effect.
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Not completely thoroughly. Ultimately, the energy source of the explosion is conversion of gravitational potential energy into kinetic, plus energy released from fusion. But exactly how that energy is transferred into the outgoing shockwave is not a trivial question.
You might think that the radiation pressure from all the photons produced by the fusion would easily explain it, but it doesn't. It's not nearly enough. It turns out that neutrinos actually play a big role, which might be surprising since they are so weakly interacting. But the core density during collapse is very high, and there are a lot of neutrinos produced. As an XKCD What If (https://what-if.xkcd.com/73/) shows, if you were close to a core collapse supernova, the neutrino radiation alone is enough to kill you! So they must supply a fair bit of pressure to the surrounding layers of the star, but even this is still not enough to completely explain the shockwave. This is an astrophysics problem which has been studied for the last several decades, and it is not yet completely solved. Fairly regularly a new paper will show up on ApJ on the subject.
I'm pretty sure that whatever the missing details are, absolutely none of them involve antigravity. :)
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The whole thing is very, very exciting. Especially because we really have no idea what's going on with the thing, only that it seems to work!
It's like a prehistoric human figuring out that a hollow tree trunk floats on water much better than a raft made of fully intact logs. No idea how it works out, just that it does.
By the way, just to clear up a slightly ambiguous part in the article:
The concept of an EM Drive as put forth by SPR was that electromagnetic microwave cavities might provide for the direct conversion of electrical energy to thrust without the need to expel any propellant.
Any asymmetric light source produces thrust without "propellant" per se - the thrust of a monodirectional source of electromagnetic radiation is F = P/c where P is basically the sum of the radiation going in one direction, and c is of course the speed of light. *
The problem is that this ratio is, of course, quite small since the reversal of the equation tells that the power requirement for attaining a given thrust is basically the thrust multiplied by speed of light - so to get 1 Newton of thrust, you need about 300 MW light source and that's, quite frankly, a lot. So the basic ratio is 300 MW/N for anything that just uses electromagnetic radiation; this doesn't break the conservation of momentum.
On the other hand, the advertised power to thrust ratio for this new mystifying device is 2.5 kW for 720 mN of thrust, which comes out to 3472 W/N - which is about 86,405 times as effective, or in the order of five magnitudes better. Enough so to make it considerably interesting as a means of propulsion and *definitely* appears to go against the conservation of momentum as we know it.
In fact, I would feel tempted to hypothesize that the device is using ambient dark matter as its active propellant... if it didn't basically go against the whole concept of "dark matter". The problem is that dark matter is supposed to be impervious to electromagnetic interaction - there would have to be some unknown interaction going on to facilitate this. There are some problems with assuming that it's "pushing against quantum plasma" - mostly because it would require a substantial re-formulation of the conservation of momentum, and there's probably going to be some messy stuff happening to relativity as well. On the other hand perhaps quantum plasma *is* a form of dark matter...
The more tantalizing possibility is actual warping of space-time, causing an acceleration-like effect which we measure as a force.
Needless to say, either way it's a really, really exciting discovery. Especially as it seems to be increasingly unlikely to be a measurement anomaly or other problem with the experiment setup.
*Math to derive the thrust of a monodirectional light source with known power P:
Power is defined as
P = dE/dt
Force is defined as
F = dp/dt
A photon's energy and momentum are:
E = hf
p = hf/c
so photon's momentum can be written as
p = E/c
which means that
dp = dE/c
and
dp/dt = dE/dt*c
which is
F = P/c <=> P = F*c
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Basically, a giant spotlight works exactly as you'd expect a rocket engine with an exhaust velocity equal to the speed of light to (using mass-energy equivalence on the power draw). The EmDrive has an effective exhaust velocity of eighty-six thousand times the speed of light.
Is it still likely that it's all just measurement error?
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It doesn't work quite like that because relativity. Assuming superluminal velocities never really works out.
The "giant spotlight rocket" uses photons as its "propellant", and while they carry momentum, they have no mass - all of their energy is in the form of electromagnetic radiation.
If you give the propellant some mass of its own, then the equation for the momentum of individual propellant particles changes. Especially if you're looking at relativistic ejection velocities, which by the way are not a practical concern at the moment.
Propellant with mass ejected at light speed would require infinite power - and would have infinite momentum as well. Doesn't happen.
Basically the more mass you move, the less ejection velocity you need. This means that the propellant flow is not as energetic. In many applications of reaction principle, the reaction mass is abundantly available, so it is more efficient to use more reaction mass (like air) which allows using less power. This is why, for example, high bypass turbojet engines are much more efficient (at subsonic speeds) than straight turbojet engines with no bypass air at all.
Spacecraft are in an unique position because they must transfer their reaction mass with them. That's why rocket engine always seek the highest ejection velocity possible - to gain the most energetic exhaust, while using as little propellant as possible.
The big thing with the EM drive is that if it turns out to be right, space travel may no longer be limited by the cold facts of the rocket equation. There may be useable propellant *everywhere* in the form of quantum plasma, as long as you can energize your drives!
And to answer your question, it's starting to look increasingly unlikely that it's just a fib or measurement error or anything of the kind. It's being reported in different, independent experiments, with consistent results.
Mad exciting.
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That's a nice wall of text but there's a reason I used words like 'equivalent' in my post. I'm comparing this to the familiar (to anyone who plays KSP) world of rocketry under Newtonian mechanics to give some sense of perspective.
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But it's specifically *not* equivalent.
Think of it this way.
As you start with massive propellant and slow ejection velocity, your rocket uses very little power (energy of exhaust) to produce a given thrust force.
As you reduce propellant particle mass and increase ejection velocity, your rocket's exhaust becomes more energetic, you need more power to produce the velocity, but your propellant flow reduces.
As you ramp up the propellant velocity and reduce the mass flow, your rocket's exhaust power increases, while the force of thrust remains equal.
As you approach relativistic speeds, your propellant flow will be minimal, but your energy demands will be very high.
Now as you move from propellant with mass to *photons*, you basically extend the curve to where ejection velocity is light speed and propellant mass flow is zero, because you of course need no propellant.
However, your thruster's energy consumption has basically reached the highest possible value per unit of force.
And that's where things stop. Exhaust velocity doesn't exceed light speed, if it did you'd get some fairly odd causal violations.
Aside from that, the analogy or "equivalency" you presented is simply incorrect, because ejection velocity is just one component of the impulse given to the exhaust - you need to know the mass as well.
All we can really say is that the thrust per electrical power ratio is about 86,000 times as much as expected from a "spotlight rocket". You can't draw any conclusions as to exhaust velocity (real or equivalent) without knowing the propellant mass flow (real or virtual).
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Jesus christ I know that it doesn't actually work that way, what I was saying was essentially that if you modded an engine into KSP with a 3*10^8m/s exhaust velocity it would behave the same way as a photon engine IRL. Honestly, I realise I didn't really make that clear in my original post but it feels like you're only skimming what I say so you can write lengthy essays on physics that I already understand.
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Yes, if you also modded the engine to only use electrical power as a resource, and if the vehicle had enough power to run the engine.
At any rate, since you didn't actually mention KSP at all, my understanding was that you were referring to real world and real physics with this:
Basically, a giant spotlight works exactly as you'd expect a rocket engine with an exhaust velocity equal to the speed of light to (using mass-energy equivalence on the power draw). The EmDrive has an effective exhaust velocity of eighty-six thousand times the speed of light.
...hence I responded with a real physics explanation on why it doesn't work like that.
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Honestly, I realise I didn't really make that clear in my original post
And no, if you use mass-energy equivalence to get a mass flow from that 300MW per Newton figure you gave, then calculate an exhaust velocity from that you find that, as I said initially, a photon drive works exactly as you'd expect a Newtonian reaction engine with an exhaust velocity of c to.
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I found that in most relativistic cases, it's more convenient to think in terms of momentum than mass. Strictly speaking, photons are massless, but there's more to momentum than just mass - relativistic equation for it gives you a mass-independent component of it. It makes things a bit easier to understand. Momentum also can increase indefinitely, is conserved and generally behaves much more neatly than either mass (which leads to this "mass increases with speed" hogwash you occasionally hear) or velocity (which has trouble with c "speed limit"). It also clears up things like Oberth effect, which are really darn hard to explain. Photon drive really does work like a newtonian reaction drive with an Isp of c (at least at low velocities), and if you consider momenta involved, it's pretty obvious why. :)
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one of the ideas for how this thing works (jumping to the assumption that it does in fact work and we haven't just had good/bad luck with error or some sort of yet undiscovered systematic error) is that it pushes on the quantum vacuum virtual plasma, but it also seems to act sort of like an alcubierre drive. crazy thought(cause that's what we get with this sort of thing), what if the quantum vacuum virtual plasma basically IS spacetime and by moving the virtual particles you are moving the spacetime along with them? might this be the key to figuring out quantum gravity? maybe warps in spacetime are equivalent to suppression of virtual particles, maybe gravity is caused by normal matter suppressing the formation of virtual particles or something like that. I can barely handwave the terms, this is way beyond my level of education in this subject.
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And no, if you use mass-energy equivalence to get a mass flow from that 300MW per Newton figure you gave, then calculate an exhaust velocity from that you find that, as I said initially, a photon drive works exactly as you'd expect a Newtonian reaction engine with an exhaust velocity of c to.
Not... exactly, but sort of, yes.
The problem with this interpretation is the age-old question of whether photons truly have "mass" or not. They certainly have momentum, and they have energy, so you can characterize the "exhaust" in terms of those, but when you calculate a mass-energy equivalency for finding the mass flow for the "exhaust" of photons, things become a bit dodgy.
True enough, the general thrust of exhaust gets the formula F = dm/dt * v, but that doesn't need to mean it must always be expressed that way. Mass flow just doesn't make a lot of sense when you're talking about massless particles. After all, that formula is just a specialized form of the general definition of thrust (F = dp/dt) and the momentum is separated into mass flow and ejection velocity simply because that makes sense in a situation where there is a mass flow and thrust is dependent on both the mass flow and ejection velocity.
Just because "Newtonian physics" happens to end up to a "correct" solution in a situation that is thoroughly beyond the realms of Newtonian physics doesn't mean it's the best way to handle or visualize the situation.
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Strictly speaking, photons are massless, but there's more to momentum than just mass - relativistic equation for it gives you a mass-independent component of it.
This is a good point. Everyone knows the formula E=mc2, but this only applies to massive particles which are at rest. The general formula is actually E2 = p2c2+m2c4. Right away you can see that massless particles have energy E=pc as Herra showed. And for massive particles which are not moving, it simplifies to E=mc2.
It also clears up things like Oberth effect, which are really darn hard to explain.
Actually no, the Oberth effect has nothing to do with this -- it is explained by classical mechanics without relativity. If you tried to explain it with relativistic effects, your prediction for its strength will be orders of magnitude too small. You really only need the definition of work to understand it, or definition of total energy (gravitational potential plus kinetic) if involving a gravitational field. To think about it, consider a rocket which is held stationary while burning. In this case, the work done on the rocket by the fuel is zero, by definition, since it is moving through zero distance. All of the work is done on the propellant -- the propellant gains all the energy from combustion. If the rocket is moving, then more work is done on it because it moves through a greater distance. This is at the cost of putting less energy into the propellant -- it is left behind with less kinetic energy.
@Herra: Great posts. I don't think it's likely that it has anything to do with dark matter (the properties of dark matter just don't really fit the bill), but dark energy might make sense, given that it's apparently a property of space-time pertaining to vacuum fields. If the quantum thruster works by interacting (somehow?) with the vacuum energy, then that's... crazy.
I've also heard a lot of speculation that the drive might be operating via general relativistic effects, of the sort involved with Mach's Principle. Mach's principle is the notion that the local standard of "rest" (the locally inertial frame) is determined by fields produced by the large-scale distribution of matter and energy in the universe. Perhaps the drive is (somehow?) interacting with those fields, thereby exchanging momentum with matter "at a distance". Which reminds of quantum entanglement sort of, and I can't help but think it can't possibly work that way because of causality issues. Then again, this thing pretty much completely defies our understanding of basic physics... we haven't seen such a confounding experimental result since Michelson-Morley over 100 years ago.
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So this is a real thing and you guys are all buying it? Hmm. That is interesting.
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The problem with this interpretation is the age-old question of whether photons truly have "mass" or not.
No, this is irrelevant. A Newtonian model of a rocket that shoots potatoes out the back at 3*10^8m/s behaves the same way as the relativistic model of a photon drive for the purposes of things like delta-v for a given mass fraction.
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I actually think it will end up having a mundane explanation, but whatever it is probably isn't straightforward or you'd think someone would have figured it out already.
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So this is a real thing and you guys are all buying it? Hmm. That is interesting.
well, so far it's shown to actually behave more or less as advertised in experimental setups, and more than one team has repeated the results. Reality is the true measure of reality, so... so far it looks like it's real even though we have no idea how it works. There is still a (much) better than not chance we'll find that it doesn't work, but so far we haven't. and that's neat.
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Be interesting to see what happens when we get to the point of throwing one of these into orbit because like Bobboau says until it works in reality it dosnt work... but yer this is an interesting time for the space sciences.
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i have a feeling there will be people calling it measurement error even if it gets mounted on a spacecraft and used to propel it, though
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i have a feeling there will be people calling it measurement error even if it gets mounted on a spacecraft and used to propel it, though
>the probe seems to have reached 0.77c
>m... margin of error!
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I actually think it will end up having a mundane explanation, but whatever it is probably isn't straightforward or you'd think someone would have figured it out already.
Pretty much, that's what my pessimist/realist side expects.
But if it's real, it's real. Honestly I'm waiting for the peer reviewed publications, full size engineering testbeds on orbital conditions, and the eventual Nobel prizes until I believe it. But so far, so good...
A Newtonian model of a rocket that shoots potatoes out the back at 3*10^8m/s behaves the same way as the relativistic model of a photon drive for the purposes of things like delta-v for a given mass fraction.
Yeah, and it turns out that the Newtonian model is wrong at relativistic speeds and with massless objects, so why should that be used in any case?
Just because the model happens to produce the right answer doesn't mean it's correct. You can't just apply a Newtonian model to a non-newtonian situation and be satisfied by the fact that it appears to be working, and assume that nothing has changed. It's even worse of an idea to use that to "explain" something to someone with a layperson's understanding of physics. It's just going to mislead them and the next thing you get is armchair physicists posing thought experiments that have the underlying structure of "if we ignore the laws of physics, what will happen according to the laws of physics".
I could just as easily say that under Newtonian physics, spotlight rocket's exhaust mass flow is zero because photons have zero mass so the entire thing has zero thrust, and be done with it.
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I was mentioning it as an illustrative analogy because calculating it myself had given me a better grasp on the quantities involved by relating it to a situation I understand quite intuitively. You still don't seem to have realised that I know all of the basic facts you keep spouting and trying to correct me on them is a fool's errand.
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Look, I understand that you have a sufficient understanding about the subject to make analogies without assuming that they are 1:1 equivalent.
What I disagree with you about is this particular point being a good analogy.
My point is that this particular apparent point of unity between relativity and Newtonian physics is completely artificial, an artefact of how the equations are set up and happen to produce same results in certain special cases.
I think it is misleading to compare the thrust of EM radiation to a thrust of imaginary Newtonian lightspeed potato gun. While you have enough understanding of the physics to "play around" with the equations, for a layperson it creates an illusion that Newtonian physics can be used in contexts where it should not be used.
In some cases, it is acceptable to say that a more basic theory can work as a subset of more advanced theory in specific conditions. Good example of this is use of Newtonian mechanics as a special case of special relativity, when v<<c (practically v<0.1c is sufficient for most applications). This is not the case here.
In other words, you can get the correct result for the wrong reasons, and that can reinforce incorrect paradigms about physical reality. While this exercise may have helped you to look at it from a different perspective, I don't think it is a good "example" to make for someone who doesn't have necessary level of knowledge and understanding of physics to already know how the actual thing works.
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There are very specific cases where Newtonian formulas give exactly the right answer for a relativistic scenario, but purely by mathematical coincidence. It's like the idiom "a broken clock is right twice a day". Another example is that you can calculate the radius of the event horizon of a black hole from the Newtonian formula for escape speed (setting it equal to c). But it works for totally the wrong reasons. Newtonian physics suggests that photons emitted from the horizon go off to infinity. They don't. It suggests that stuff thrown upward from just inside the horizon can, at least briefly, pass through it. Never happens. Newtonian physics even suggests that particles falling into the hole will always miss the singularity. Not only do they hit the singularity, it is impossible to avoid it. I agree with Herra that it's not a good idea to explain -- even for the sake of just obtaining numbers -- relativistic phenomena with Newtonian arguments. Even if you understand the relativity, you risk causing confusion for those who don't. I can't tell you how many times I've seen people try to calculate relativistic stuff with Newtonian formulas and get the answer wrong by orders of magnitude! And if you do understand the relativity, then why not use it to get the right answers for the right reasons?
Seriously though, let's move on to talking about the cool stuff again. Vacuum fields and virtual particles and wtf is up with this experiment?
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thoughts about this maybe giving us some sort of insight into quantum gravity?
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I concur, the cool stuff is much cooler.
For example, are vacuum fields - or in fact fields in general - actual physical entities? Or just mathematical models for things?
And what implications would it have if the vacuum field turns out to be something you can "push" against? Is there some way to measure velocity relative to this vacuum? Does it act as some sort of universal reference frame? What happens if you put two EM-drives against each other end to end so they're dealing with each other's "exhaust" flows??
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I agree with Herra that it's not a good idea to explain -- even for the sake of just obtaining numbers -- relativistic phenomena with Newtonian arguments.
Good thing that wasn't what I was doing!
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no one cares who was doing what. no one is going to remember or care about who won this argument about semantics an hour after it's settled or an hour from now.
what happens if you put two em drives pushing against each other? does the space between them become 'less virtual' or something?
also, what are some of the arguments against mutability of the quantum foam (assume I am going to get some terminology slightly wrong)? I've heard things like because protons are the same no matter when they were made proves that the virtual plasma must be immutable. doesn't that just imply that there is a certain respect in which it has not changed? not that there is no way to change it, or that there are other ways in which it could and often does change?
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As I understand it - and I could be way, way wrong here - the argument goes that you can't push against the virtual particles in the vacuum because empty space ought to be at the absolute lowest energy state possible. If its possible to extract kinetic energy out of it, then that throws that idea right or the window.
Personally, I'm super skeptical about this, for the whole extraordinary claims, extraordinary evidence thing - we all remember the whole "faster than light neutrinos" debacle. But I'm also really, really hoping that this is legit, because it seems like it would be the first major flaw in physics since the discovery of the acceleration of the expansion of the universe. And this one also related to inexplicable kinetic energy. I'm hoping that the more data we get that disagrees with the current paradigm, the better the chances of someone coming along who can shift that paradigm. These experiments might just be the missing corner piece of the puzzle that lets somebody bust open the dark matter/energy problems. Very exciting... with that great big caveat of scepticism, of course.
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but you are not extracting energy out of it, you are using it as a catylist to convert one form of energy into another, the system containing the thruster has the same total energy after it started moving as it did before. it's just now it has more kinetic and less electrical (as a general place holder for energy storage that get converted to electricity at some point in the process)
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Here's the thing: Conservation of energy is an approximation. It kind of doesn't hold absolutely, you can "borrow" energy for a while, but over a period of time things average out and the conservation of energy applies. On macroscopic scales, generally.
One such case would be Hawking radiation, where virtual particles end up spawning so that one falls into the event horizon and the other one escapes. The interesting thing is that energy over the entire event must conserve, so even though a particle "falls" into the event horizon, the end result is that the mass of the black hole decreases, while the energy of the universe outside event horizon increases by the amount of one particle (which transforms from virtual to real during the event).
To draw an analogy to the EM drive - assuming it really does work - the total energy must conserve. Looking at a situation where the drive is mounted on a small spacecraft - the spacecraft gains kinetic energy, and that must come from somewhere. One really interesting possibility is that this energy actually comes from vacuum energy - in other words, the thruster would generate a "bubble" of space behind it with energy density below the zero point energy of vacuum - which may not exactly be negative energy in the sense of requiring exotic matter and such, but it's functionally quite close to it. Especially if space-time geometry is dependent on the vacuum's energy state, which it probably is.
That would offer quite a tantalizing explanation to the warp field interferometer observations which apparently suggest that the EM drive actually does produce a space-time distortion of some variety.
In addition, if the apparent force is actually the result of some space-time anomaly, then it doesn't even break the conservation of momentum. In some ways, it could be considered artificial gravity.
I wonder if an accelerometer onboard a spacecraft with EM thrusters would actually measure acceleration, or not? Or would the measured acceleration depend on distance from the drive unit?
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oh hey, what would happen if you bolted an em drive to the ground and powered it up? what would happen to small objects placed in their immediate vicinity?
if you bolted it vertically could you use it to train to battle Frieza?
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One really interesting possibility is that this energy actually comes from vacuum energy - in other words, the thruster would generate a "bubble" of space behind it with energy density below the zero point energy of vacuum - which may not exactly be negative energy in the sense of requiring exotic matter and such, but it's functionally quite close to it. Especially if space-time geometry is dependent on the vacuum's energy state, which it probably is.
That would offer quite a tantalizing explanation to the warp field interferometer observations which apparently suggest that the EM drive actually does produce a space-time distortion of some variety.
In addition, if the apparent force is actually the result of some space-time anomaly, then it doesn't even break the conservation of momentum. In some ways, it could be considered artificial gravity.
Give it to me straight, you guys: are we in Star Trek?
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I seem to once remember reading a theory that Star Trek is real and someone came back from the future to inspire Gene Roddenbury so as to ensure that their future would actually occur. It would explain why stuff he supposedly invented out of thin air seems to be possible when scientists try to do it later. :p
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Here's the thing: Conservation of energy is an approximation. It kind of doesn't hold absolutely, you can "borrow" energy for a while, but over a period of time things average out and the conservation of energy applies. On macroscopic scales, generally.
One such case would be Hawking radiation, where virtual particles end up spawning so that one falls into the event horizon and the other one escapes. The interesting thing is that energy over the entire event must conserve, so even though a particle "falls" into the event horizon, the end result is that the mass of the black hole decreases, while the energy of the universe outside event horizon increases by the amount of one particle (which transforms from virtual to real during the event).
To draw an analogy to the EM drive - assuming it really does work - the total energy must conserve. Looking at a situation where the drive is mounted on a small spacecraft - the spacecraft gains kinetic energy, and that must come from somewhere. One really interesting possibility is that this energy actually comes from vacuum energy - in other words, the thruster would generate a "bubble" of space behind it with energy density below the zero point energy of vacuum - which may not exactly be negative energy in the sense of requiring exotic matter and such, but it's functionally quite close to it. Especially if space-time geometry is dependent on the vacuum's energy state, which it probably is.
That would offer quite a tantalizing explanation to the warp field interferometer observations which apparently suggest that the EM drive actually does produce a space-time distortion of some variety.
In addition, if the apparent force is actually the result of some space-time anomaly, then it doesn't even break the conservation of momentum. In some ways, it could be considered artificial gravity.
I wonder if an accelerometer onboard a spacecraft with EM thrusters would actually measure acceleration, or not? Or would the measured acceleration depend on distance from the drive unit?
So are we talking about a delay in the "balancing the books" so to speak in terms of the energy values which is generating the thrust?
I seem to once remember reading a theory that Star Trek is real and someone came back from the future to inspire Gene Roddenbury so as to ensure that their future would actually occur. It would explain why stuff he supposedly invented out of thin air seems to be possible when scientists try to do it later. :p
I also remember a quote which I cant place about science fiction driving science, I mean this EM + Vacuum drive seems a little close to a possible explanation of impulse drive
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In all this enthusiasm, please remember that this is still not a reliably confirmed result. Please check out this article by Ethan Siegel (http://www.forbes.com/sites/ethansiegel/2015/05/04/no-nasa-did-not-accidentally-invent-warp-drive/).
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To draw an analogy to the EM drive - assuming it really does work - the total energy must conserve. Looking at a situation where the drive is mounted on a small spacecraft - the spacecraft gains kinetic energy, and that must come from somewhere. One really interesting possibility is that this energy actually comes from vacuum energy - in other words, the thruster would generate a "bubble" of space behind it with energy density below the zero point energy of vacuum - which may not exactly be negative energy in the sense of requiring exotic matter and such, but it's functionally quite close to it. Especially if space-time geometry is dependent on the vacuum's energy state, which it probably is.
This has no chance of being related to a metastability event, right?
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In all this enthusiasm, please remember that this is still not a reliably confirmed result. Please check out this article by Ethan Siegel (http://www.forbes.com/sites/ethansiegel/2015/05/04/no-nasa-did-not-accidentally-invent-warp-drive/).
Yeah, this really can't be emphasized enough.
I'd really like for it to be true, but I won't believe it is true until it withstands a great deal more rigorous testing. Ideally, have an independent group use it to change the orbit of a satellite, preferably in a predictable manner, and one incompatible with other causes of orbital evolution (tides, drag, and whatnot). That would be extremely compelling; you cannot easily fake or misinterpret such a result, assuming its magnitude is large enough, which current claims of this drive's capability suggest it would be. So, if this thing is legit, it should not take an inordinate amount of time to demonstrate it. But it might take a fair amount of money.
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Yeah, it's a very good read.
It's still fun to fantasize, right? It's all fun and games, and we get to follow the story as it develops anyway.
So on the one hand, I'm still conscious of all the facts mentioned in the article, and I'm still sort of suspicious about the whole thing, but on the other hand...
(http://i1.kym-cdn.com/photos/images/original/000/283/235/7e3.jpg)
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we have not yet discovered new physics, we have discovered a hand full of faint anomalous results. But that article seems to be misrepresentative and is overly confident in it's own right. I mean just starting with the title, how do we know NASA hasn't just inadvertently invented a warp drive, so far the results are inconclusive but positive we don't know what this mass of copper is yet, it might be a really bad warp drive, or it might be a heavily over engineered paper weight , until more tests are done on it saying 'this isn't happening' is just as irresponsible as saying it is happening. there are only a handful of people in the world who will be able to really say anything about this device with any degree of authority, and that authority is entirely founded on their ability to say how other people can do this too, until that happens or until they say "yeah, upon further investigation turns out this didn't work" all the rest of us can really do is speculate.
...or build our own device (https://drive.google.com/folderview?id=0B4PCfHCM1KYoTXhSUTd5ZDN2WnM&usp=sharing) and try to run the experiment our selves, assuming we have access to a high precision torque balance, a vacuum chamber, and we know how to mess with a magnetron without killing ourselves.
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Would be funny if Elon Musk took those schematics and replicated the experiment successfully.
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and then licesnsed the technology and we ended up with flying Teslas.
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I'd hit it. :yes:
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The Forbes article makes a few points that are flawed.
The upper limits for test force in these experiments is actually above three standard deviations of the limits. This could perhaps be a problem with one lab producing the results, but if three labs can reproduce similar results, then the likelihood that the it is the measuring device falls even further. An anomalous occurrence above two standard deviations is surprising when it happens but is understood to occasionally occur. An anomalous occurrence above three standard deviations is pretty significant and would be even more so when similar problems are shared by three different labs (which are also performing null experiments). (Forgive me if I understand standard deviation incorrectly. I actually really dislike statistics.)
The reliability of the equipment can also be verified by setting up experiments where known forces are involved to test the equipment. Furthermore, we just mentioned how many orders of magnitude greater these forces are to traditional EM propulsion, even if the measurement is inaccurate, it's significance is not reduced.
The writer fairly points out the original creator has made bold claims in the past. However, this is not salient in the face of three independent labs. Even a complete crackpot could get lucky, and the original creator doesn't sound like a crackpot. He also displays a lack of understanding of the devices in question: he mentions that their outputs aren't directly related without mentioning that they are made of different materials, as has been known from many other sources.
Additionally, many so called laws are frequently bent or broken in science because their exceptions are based upon truths that are just as fundamental. It's true, you can't measure both position and momentum of particles with arbitrary accuracy, but that's only true if you measure one particle. If you measure many particles whose positions and momenta fall under a bell curve, then you can measure the mean of both and then therefore know both things for some particles (when both happen to occur in the same particle).
The rule is bent. And it make sense: our existential reality is based on us living in this weird universe that doesn't behave to our eyes like the quantum world does because of the loopholes we live in. Things classical physics and chemistry work because we live in a world of loopholes. I was reading recently that magnetars have such powerful magnetic fields that our electrons would become deformed and cause our very biochemistry to cease. The universe could have existed such that all space was completely filled with magnetars or black holes, but that's not how it happened. We don't live because the universe has laws, we live because it has laws and also happens to have quasi-exceptions to these laws. Why can't the EM drive be one of these loopholes?
My final point is that the writer's argument is feckless. This isn't the tachyonic neutrino, something so obviously wrong that it would completely change our understanding of the universe. It's more likely to be a unique quantum or space-time effect that relies on a set of very specific conditions, which this lab has happened upon, and which we can hopefully exploit in the future.
The fact remains that something is happening that we do not understand.
If the author wants us to be cautious, it should be an argument based on how the device scales up. We have no guarantee that the force exhibited by the device will grow as the device grows in size or that it will work in space the same way that it works on Earth. It simply needs to be tested and understood, and it is a possibility of such significance that it is worth the investment and time that are necessary for those things. In fact, it is better if the public gets excited about it so that it can get funding more easily so that we can see what's actually going on.
If all these labs are lying, they will be discredited -- their very careers will probably end. If it's proved wrong, oh well, we feel disappointed. Why should I avoid being disappointed by removing my hope? What gain is there in that pursuit? The result of that is I will only feel angry and annoyed for quashing my own emotions. And if I do feel disappointed, I will become more mature overall once I get through it. I'm with Herra and hoping for it to succeed.
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Clearly it's the luminiferous aether. FS3 confirmed.