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Posted: Sun May 16, 2010 3:52 pm
by BenTC
hanelyp wrote:
There's no violation of CoM. You're tugging at the rest of the universe.
How is that observationally different from non-conservation of momentum?
Pure naive speculation here... Since momentum depends on mass, and mass==energy, perhaps conservation of momentum in maintained by the energy expended cycling the mass that is pushed/pulled against.

Posted: Sun May 16, 2010 4:23 pm
by Skipjack
I dont think that anybody is claiming that ME thrusters do not need an energy input to create an acceleration. Of course they do. They just dont need to expell mass in order to generate thrust. That is at least what what I understand.

Posted: Sun May 16, 2010 6:36 pm
by D Tibbets
kcdodd wrote:You could do that with electromagnetic radiation pressure.

I am looking for a physics explanation. Not hand wavy arguments. A published paper, perhaps?

I expect that IF the force is from gravitational field (which I doubt), the missing momentum would have to be expelled as gravitational waves. Gravity waves have not even been detected as of yet.
True, gravitational waves have not been detected, but they are accepted as a part of mainstream physics, especially astrophysics. It is used to explain neutron star spindown, among other things. And, it is valid enough to justifly spending a lot of money searching for them. If they indeed exist, it is prooving exceedingly difficult to dectect them from massive events like supermassive black hole mergers. A triffling event like a spaceship moving or a star exploding would be many orders of magnitude more difficult.

Dan Tibbets

Posted: Sun May 16, 2010 6:54 pm
by chrismb
D Tibbets wrote:If they indeed exist, it is prooving exceedingly difficult to dectect them from massive events like supermassive black hole mergers.
If anyone finds [incontrovertibly] either gravitational waves, or the Higgs Boson, then, as per above, I'll buy a hat and write on it "The origin of gravity isn't thermodynamic after all! Forces do exist. I was such a dunce!"... and then eat it!

Posted: Sun May 16, 2010 7:03 pm
by D Tibbets
chrismb wrote:I should add, to reply to my own post, that this M-E mularky is of interest to me because it is [perhaps unwittingly] attempting to use a change-of-state (electrical) with a dimensional change (oscillatory). As I have shown above, there should be some 'forces' manifest here. Unfortunately, the system appears to return back to the same state each cycle, and as a corollary of the above is that force is the derivative of system-state change with respect to displacement, even if there is a displacement there is no state-change obvious here.

I would expect an out-of-phase force response to the electrical cycle, which may be useful in some scenarios but not, I think, in propulsion.

I would like to see someone analyse these systems, according to the above intalicised axiom.
I don't follow your logic. Certainly force fields are used to determine / predict events. Like an electron accelerating in an electrical field. Certainly, I understand that there has to be an energy exchange for something to happen (a photon with the electromagnetic force). but what drives that photon exchange if not something? It seems mostly a matter of semantics and a lack of understanding. The various theories are useful tools for predicting what will happen, but they don't necessarily define what is real. This applies to quantum mechanics just as it does to the macroscopic world. Also, keep in mind that cause and effect can be a two way street (look at quantum entanglement) Also, consider that things that happen very quickly, then reverse never happened at all (times shorter than Plank's time).

After all, I don't believe science has a 'real' definition of reality. While geometry has some base definitions of a point, line, and plane that is used to derive everything else, the universe's arbitarily defined starting point is the big bang singularity. How inflation occured (was derived from that) is unknown. In fact, the big bang singularity is an assumption . Where did it come from? There is no answer, despite various string and brane theories. At most, thay only push the assumptions further back. Hawking's dodge is that we can't consider what happened before the big bang, because there was no before(because time did not exist), is convenient but meaningless

Everything is derived from faith, whether the universe was created in a big bang, or an act of God (where did he come from?) we are forced to take it on faith. In that regard the anthropomorphic principle is as valid as any. We are because we think we are.


Ouch! - and that is without ever taking a Philosophy course.

Dan Tibbets

Posted: Sun May 16, 2010 7:31 pm
by Betruger
off topic

Posted: Sun May 16, 2010 8:36 pm
by chrismb
D Tibbets wrote:Everything is derived from faith, whether the universe was created in a big bang, or an act of God (where did he come from?) we are forced to take it on faith.
No. This is quite incorrect. There are self-standing axioms that would be true for any one, any where, in any type of universe, and whether you are dead or alive. A simple example are the 5 euclidean solids. These are a different sort of 'imagined' thing, they can be shown to 'exist' and any intelligent creature at any point in, or out, of time and space could consider and conclude that there are 5, and only 5, regular 3 dimensional shapes.

In a similar way, but more difficult to argue perhaps (hence I started with something elementary), the notion of force is almost impossible to describe - no matter how useful the concept. To try to comprehend how forces prevent my montior, in front of me, from sinking into my table is an enormously difficult stretch, though we can conceptualise the whole issues as a 'force' and declare a reaction to the weight of the montor. You seem to be arguing that you're happy to take that as a faith-based observation, but there is no need when you consider that for the monitor to sink into the table would require a rapid decrease in entropy for which there is no latent energy to feed that process, hence it doesn't happen. This doesn't *need* to be a faith based observation because I am simply, and only, basing my observation on the very simplest of axioms; that the monitor and table are different things that are located with respect to each other. The consequence stemming from the axiom and thermodynamics is that either they can mix and release energy, or they would need energy to do so and there isn't any freely avaliable. The monitor and the table are not mixing so all I have to observe is that there is no free energy which they can use to do so, whereas you are left in your *faith based* darkness of understanding of why the monitor doesn't sink into the table and have to dream up 'a reaction force' to help you get by in life without getting too confused about it. You will be compelled to wonder how the electric fields of the electrons at the surfaces of these object repell each other, and then you might start wondering why, if the electrons get so close together that they interact electrically, that some chemical process doesn't go on such that any two substances don't start interacting chemically when they sit on top of each other.

The notion of 'forces' is great for doing engineering and basic physics, but they start to let you down when you probe the reality of matter and reality a little more.

I realise this might offend your conventionality of education. After all, I am sure you were taught that Newton said that an object remains at rest until a force acts on it, but you weren't encouraged to ask 'why does it move, then, once a force *is* applied?'. To get an object moving you have to put in energy. But energy is force over distance, yet if an object is stationary then how do you apply a force? [It's a rhetorical question, because you can then include lots of 'patch-up' ideas to make it work. Impusle and momentum, in this case. But they *are* patch-up ideas and if you believe in them all then you'll end up building M-E thrusters and other anti-gravity ideas. 'Forces' let you down, in the end, and you have to move to pure entropy considerations to make sense of things.]

Posted: Sun May 16, 2010 9:42 pm
by icarus
bedregger:
The weblinks are there. Get to work.
I'm not the one spouting this junk physics on a public forum. I'm afraid the onus is on you to prove you are not a raving idiot pushing the Kool-Aid cart. I won't be getting to work for you or anyone, in fact why don't you go and get .... well need I say anymore?

Posted: Mon May 17, 2010 12:42 am
by Betruger
off topic

Posted: Mon May 17, 2010 1:45 am
by icarus
Before you descend again into outright name-calling and abuse, how about you just answer the question instead of obfuscating? You were the one who bought these junk physics arguments up after all ... re: your 'universe tugging to circumvent conservation of momentum' statement

"What happens to the center of mass of the universe when you do this 'tugging' thing on it that you are talking about?"

Just attempt to think, and then answer the question and you'll see how ridiculous the proposition, and your statement is.

Posted: Mon May 17, 2010 3:26 am
by Betruger
That it's a gravitational interaction is clearly stipulated right off the bat.
Image

Posted: Mon May 17, 2010 3:58 am
by paulmarch
chrismb wrote:
D Tibbets wrote:Everything is derived from faith, whether the universe was created in a big bang, or an act of God (where did he come from?) we are forced to take it on faith.
No. This is quite incorrect. There are self-standing axioms that would be true for any one, any where, in any type of universe, and whether you are dead or alive. A simple example are the 5 euclidean solids. These are a different sort of 'imagined' thing, they can be shown to 'exist' and any intelligent creature at any point in, or out, of time and space could consider and conclude that there are 5, and only 5, regular 3 dimensional shapes.

In a similar way, but more difficult to argue perhaps (hence I started with something elementary), the notion of force is almost impossible to describe - no matter how useful the concept. To try to comprehend how forces prevent my montior, in front of me, from sinking into my table is an enormously difficult stretch, though we can conceptualise the whole issues as a 'force' and declare a reaction to the weight of the montor. You seem to be arguing that you're happy to take that as a faith-based observation, but there is no need when you consider that for the monitor to sink into the table would require a rapid decrease in entropy for which there is no latent energy to feed that process, hence it doesn't happen. This doesn't *need* to be a faith based observation because I am simply, and only, basing my observation on the very simplest of axioms; that the monitor and table are different things that are located with respect to each other. The consequence stemming from the axiom and thermodynamics is that either they can mix and release energy, or they would need energy to do so and there isn't any freely avaliable. The monitor and the table are not mixing so all I have to observe is that there is no free energy which they can use to do so, whereas you are left in your *faith based* darkness of understanding of why the monitor doesn't sink into the table and have to dream up 'a reaction force' to help you get by in life without getting too confused about it. You will be compelled to wonder how the electric fields of the electrons at the surfaces of these object repell each other, and then you might start wondering why, if the electrons get so close together that they interact electrically, that some chemical process doesn't go on such that any two substances don't start interacting chemically when they sit on top of each other.

The notion of 'forces' is great for doing engineering and basic physics, but they start to let you down when you probe the reality of matter and reality a little more.

I realise this might offend your conventionality of education. After all, I am sure you were taught that Newton said that an object remains at rest until a force acts on it, but you weren't encouraged to ask 'why does it move, then, once a force *is* applied?'. To get an object moving you have to put in energy. But energy is force over distance, yet if an object is stationary then how do you apply a force? [It's a rhetorical question, because you can then include lots of 'patch-up' ideas to make it work. Impusle and momentum, in this case. But they *are* patch-up ideas and if you believe in them all then you'll end up building M-E thrusters and other anti-gravity ideas. 'Forces' let you down, in the end, and you have to move to pure entropy considerations to make sense of things.]
Chris:

Would you please point us to some peered reviewed papers on these energy/entropy ideas you are espousing? I’ve known for a long time that there are disconnects between the energy and force definitions, and it could be education for me to see another viewpoint.

Thanks much.

Posted: Mon May 17, 2010 4:04 am
by paulmarch
Betruger wrote:Give up the purse swinging. I called it exactly like it is. Taking my off-hand comment of the rough dynamics as premise for debate of the exact physics of it is ludicrous.

1) I'm only pointing out the very rough dynamics of it, and 2) that I might be wrong. Said so explicitly. And 3) gave directions to the resources with the exact math and papers. I'm not arguing anything about whether it's credible.
Just attempt to think, and then answer the question and you'll see how ridiculous the proposition, and your statement is.
No kidding. It's a ridiculous theory? I didn't come up with it. There's no circumventing conservation of momentum because the violation of CoM is only apparent. Why is it not violating COM? Because it's actually interacting with the rest of the Universe, HENCE "tugging" at it. If you want the exact details, see the papers. IIRC 93143 WAG'd that the rest of the Universe might get that bit cooler from it.

That it's a gravitational interaction is clearly stipulated right off the bat.
Image

I don't get what the point of this is, when the actual physics are right there to dig into. Textbook strawman.
Folks:

Here is a small excerpt from Jim Woodward's latest paper on the M-E that seems pertinent to this discussion.

"Armed with the knowledge that general relativity theory, the EEP, and Mach’s principle – the gravitational nature of inertial reaction forces – are all correct, and that the propulsion problem is actually stated as: how can we make Jupiter masses of exotic matter – in our electric spacecraft using relatively low energy fields – to form wormholes and warp drives? We now ask: how does Mach’s principle help? Mach’s principle helps in two ways. First, it tells us that the usual conception of the “force” of gravity being decades of orders of magnitude smaller than the other forces of nature is wrong. That conception views the “force” of gravity as that which causes deviations from flat space inertial motion by the presence of local objects. But general relativity theory tells us that the presence of local objects does not produce “forces”. It distorts the local spacetime and causes inertial motion to deviate from that that would otherwise occur in flat spacetime. True gravitational forces are inertial reaction forces, and they are not small. They are as large as the forces that excite them. True, it takes all of the mass-energy in the causally connected part of the universe – most of it very far away – to produce these large forces. But that does not alter the fact that the forces are large. Indeed, we can produce very large gravitational forces simply by giving local objects very large accelerations."

Posted: Mon May 17, 2010 4:33 am
by 93143
icarus wrote:"What happens to the center of mass of the universe when you do this 'tugging' thing on it that you are talking about?"

Just attempt to think, and then answer the question and you'll see how ridiculous the proposition, and your statement is.
Nothing happens to it - so long as you consider the M-E spacecraft to be part of the universe. You do consider a spacecraft to be part of the universe, don't you?

Posted: Mon May 17, 2010 5:59 am
by MSimon
chrismb wrote: viz. inertia is thermodynamic in origin
Some very smart people might disagree with you. i.e. Feynman Chap 28 of Volume 2 Lectures