Quote from: gargoyle99 on 11/17/2015 08:21 PMYou can't talk about a constant ratio of force to input power in a time invariant fashion for a closed system if you want to respect conservation of energy over time.I just read the "Mach Effect Thrusters (Mets) And 'Over-Unity' Energy Production" paper.As is known, F=ma, that is, F=dp/dt=Ma=Mdv/dt.The paper goes on to assume that F is constant, but this cannot be, except within a narrow time frame in a closed system such as a rocket. In classical rocketry, one carries one's F with them as propellant. In an MET thruster, one also needs to carry one's F with them, in this case a source of electrical power, which will inevitably run out.Again, the Force can remain constant, within the limits of the machinery for a certain finite amount of time, but eventually, one runs out of F, that is, electricity.To my thinking, this means that one never gets to an 'over unity' situation, because one runs out of gas, as it were.If there were ever to be an MET rocket, it would accelerate to some speed, run out of power, and then it would have a constant velocity, until that velocity was perturbed by another gravitational body.Hopefully not head on.

You can't talk about a constant ratio of force to input power in a time invariant fashion for a closed system if you want to respect conservation of energy over time.

Why doesn't a Bussard Ramjet violates conservation of energy? It collects fuel from the interstellar medium and keeps accelerating forever (like in the excellent book Tau Zero)Isn't any analogy with reactionless drives possible, just that the "fuel" it captures is, lets say, more immaterial?

"It is true that constant force over enough time will violate conservation of energy."Well, glad we agree with reality as is currently known by science. Again, this discussion of 'over unity' has not yet been shown to have merit. Shown, as in floating the device into a conference room, or by a peer reviewed paper which holds up to simple scrutiny on conservation of energy.Got math?

Why doesn't a Bussard Ramjet violates conservation of energy? It collects fuel from the interstellar medium and keeps accelerating forever (like in the excellent book Tau Zero)

dustinthewind,The problem is all the equations governing electromagnetism are time symmetric. That is the ultimate source of conservation of momentum. If you want to violate conservation of momentum you will have to disprove the entirety of electromagnetic theory. If it is wrong then you cannot use it to derive your drive. You will have to find where it gives incorrect predictions and use that to derive the correct theory. Then use the correct theory to invent your drive.That will be hard because they have looked really really hard and the universe seems to be time symmetric at all relevant energy.

Quote from: ppnl on 02/21/2016 06:09 PMdustinthewind,The problem is all the equations governing electromagnetism are time symmetric. That is the ultimate source of conservation of momentum. If you want to violate conservation of momentum you will have to disprove the entirety of electromagnetic theory. If it is wrong then you cannot use it to derive your drive. You will have to find where it gives incorrect predictions and use that to derive the correct theory. Then use the correct theory to invent your drive.That will be hard because they have looked really really hard and the universe seems to be time symmetric at all relevant energy. I don't intend to violate either conservation of momentum or energy. I used both in the math below. Imagine a ball created out of one wall, inside the ship, similar to the wall emitting a photon. Now imagine this ball is perfectly elastic and has an initial velocity. We are going to do a trick where we modify the mass of the ball when it strikes one of the walls such that the energy exchange to the walls is more efficient. When the ball strikes the other wall it is back to its previous mass where the energy exchange is less efficient. Eventually the ball will slow down because its energy is being given to the structure as a whole. The ball is in analogy to a photon so instead of slowing down it is red-shifted.I attached a gif of the math I did below. It shows the % of energy exchanged between a wall and the ball depends on the mass of the ball. You then have to consider independently the exchange between two different walls where the mass of the ball is modified with each bounce. This is the reason I suggested the super-conductor because I think it suggested it could modify the mass of the photon. (One wall being a superconductor.) The idea is supposed to conserve momentum. The ball will of course change velocity with each bounce but we then sub the new velocity in and figure the exchange of energy when it bounces again. Eventually most the energy is given to one wall rather than the other.

Imagine a ball created out of one wall, inside the ship, similar to the wall emitting a photon. Now imagine this ball is perfectly elastic and has an initial velocity. We are going to do a trick where we modify the mass of the ball when it strikes one of the walls such that the energy exchange to the walls is more efficient. When the ball strikes the other wall it is back to its previous mass where the energy exchange is less efficient. Eventually the ball will slow down because its energy is being given to the structure as a whole. The ball is in analogy to a photon so instead of slowing down it is red-shifted.

Quote from: dustinthewind on 02/22/2016 01:44 AMQuote from: ppnl on 02/21/2016 06:09 PMdustinthewind,The problem is all the equations governing electromagnetism are time symmetric. That is the ultimate source of conservation of momentum. If you want to violate conservation of momentum you will have to disprove the entirety of electromagnetic theory. If it is wrong then you cannot use it to derive your drive. You will have to find where it gives incorrect predictions and use that to derive the correct theory. Then use the correct theory to invent your drive.That will be hard because they have looked really really hard and the universe seems to be time symmetric at all relevant energy. I don't intend to violate either conservation of momentum or energy. I used both in the math below. Imagine a ball created out of one wall, inside the ship, similar to the wall emitting a photon. Now imagine this ball is perfectly elastic and has an initial velocity. We are going to do a trick where we modify the mass of the ball when it strikes one of the walls such that the energy exchange to the walls is more efficient. When the ball strikes the other wall it is back to its previous mass where the energy exchange is less efficient. Eventually the ball will slow down because its energy is being given to the structure as a whole. The ball is in analogy to a photon so instead of slowing down it is red-shifted.I attached a gif of the math I did below. It shows the % of energy exchanged between a wall and the ball depends on the mass of the ball. You then have to consider independently the exchange between two different walls where the mass of the ball is modified with each bounce. This is the reason I suggested the super-conductor because I think it suggested it could modify the mass of the photon. (One wall being a superconductor.) The idea is supposed to conserve momentum. The ball will of course change velocity with each bounce but we then sub the new velocity in and figure the exchange of energy when it bounces again. Eventually most the energy is given to one wall rather than the other. But that is as simple and obvious a violation of conservation of momentum as you could ever hope for. And it leads to an immediate violation of conservation of energy. If you turn on your engine and accelerate up to some non zero momentum then you have created that momentum out of nothing. The only way to avoid it is if you can point to something that was accelerated in the opposite direction and has negative momentum to cancel out your positive momentum.

so a photon is the quantum of the EMF which is composed of a magnetic component and an electrical component. so what makes a photon? does an electron "date" a monopole? what?

The photon rebounds and now hits the back wall transferring its momentum to the back wall slowing the cavity again but re-gaining its energy (blue-shifted).

Quote from: dustinthewind on 02/23/2016 01:32 AMThe photon rebounds and now hits the back wall transferring its momentum to the back wall slowing the cavity again but re-gaining its energy (blue-shifted).That's the part that doesn't happen.

Quote from: Paul451 on 02/23/2016 06:20 PMQuote from: dustinthewind on 02/23/2016 01:32 AMThe photon rebounds and now hits the back wall transferring its momentum to the back wall slowing the cavity again but re-gaining its energy (blue-shifted).That's the part that doesn't happen.How so?

Quote from: dustinthewind on 02/24/2016 12:04 AMQuote from: Paul451 on 02/23/2016 06:20 PMQuote from: dustinthewind on 02/23/2016 01:32 AMThe photon rebounds and now hits the back wall transferring its momentum to the back wall slowing the cavity again but re-gaining its energy (blue-shifted).That's the part that doesn't happen.How so?The photon can't recover its original energy while imparting less momentum on the second wall than it transferred to the first. The first example is of a cavity that doesn't absorb the photons energy. Only the 2nd example does this.After the photon pushes the front wall and hence the ship, the photon is blue-shifted relative to the now-moving back wall. When it reflects, it will therefore impart more energy than it gave the front wall, relative to the new frame-of-reference of the ship. Correcting for the ship's change of frame, the extra energy imparted on the back wall will be exactly the same energy as the front wall, relative to a stationary observer. Ie no net acceleration.Correct on no net acceleration, however, the cavity has moved a bit having both accelerated and then decelerated. This is still the first example where the photon recovers its original wavelength which is (blue shifted) with respect to its previous red shift but technically it just recovers its original wavelength. We are dealing with a perfectly elastic photon so I should say we are dealing with a superconductive cavity. The frame I am considering is a frame that is independent of the cavity or the photon. Originally, it was stationary with the cavity. Sort of a lab frame. The wall that first welcomed the photon is moving away from that frame when re-emitting the photon so I consider it red-shifted as well as being red-shifted having imparted some of its energy into the cavity.If the energy transfer process is somehow asymmetrical, and the front wall somehow reflects "harder" than the back wall and so the ship remains moving forwards after the back-wall reflection, then the photon will be remain red-shifted (lower energy) relative to the front-wall after the rear-wall bounce. The photon will always have less energy to give the front wall than it has to give the back, proportional to the excess energy from the first bounce. That red/blue asymmetry between the front and back walls will always be equal and opposite to the asymmetry in the hardness-of-reflectivity of the two walls.Ok this is the 2nd example. It's correct the photon becomes more and more red-shifted in this case. By the ballistics the photon being heavier when it strikes first wall then more momentum is transferred to the cavity 2%. With it also being perfectly elastic and throwing the photon back it receives twice the momentum. On striking the back wall it never recovers its previous wavelength (energy) w.r.t. the lab frame and remains red-shifted. Having only recovered 1% its original energy and with reflection, twice this, then it is now short by -4%+2%=-2%, or this is just a rough approximation. With this reduced energy it continues its previous cycle. The net effect is always going to be a ship that sits stationary, getting a bit warmer as it converts the stored energy that powers the magic wall into waste heat.mmm, maybe I didn't clarify early on that the stipulation was that the photon was perfectly elastic. A real photon of course will also generate waste heat as a real ball isn't perfectly elastic but I am assuming for a superconductor it should be about 100% elastic. For being perfectly elastic all the energy goes into the ballistics and is converted into momentum (ideal assumption).Looking back at your description, I get the impression that you've visualised the red/blue asymmetry occurring in the same direction as the reflection asymmetry. That cannot happen.I am not sure we actually disagree with the change in wavelength. I was analyzing from a non-accelerated frame that was independent of the cavity, since the cavity is periodically accelerated.So ultimately, an individual incoming photon has a specific net energy vector. It doesn't matter what you do, how you transform that photon, the net energy vector for the whole system (photon+ship) must remain the same.Correct, there is conserved energy. In the first example I gave, the photon only ever gave the cavity a very small percentage of its momentum/energy, and only periodically. The 2nd example the cavity absorbs everything.What you've described is ultimately just an elaborate way for the front wall to absorb the energy of the incoming photon, there's no "pumping" effect from the cavity. And if you absorb the energy of the incoming photon, you simply convert one unit-vector of energy from the photon into one unit-vector of energy of the ship. No matter how you absorb that photon's energy, the output can only ever be one unit of energy in the same vector as the original photon.(If you reflect the incoming photon (solar sail), you can have a system which is two units forward and one unit aft. So your "red-shift cavity" ship is actually less efficient than a solar sail of the same cross-sectional area.)The cavity should be more efficient than a solar sail in that a solar sail lets the photon escape with energy. The photon only ever transfers a small amount of its momentum to the solar sail due to its incredibly minuscule mass/energy (mass being related to energy) with respect to the sail. This is the main reason photon propulsion is so inefficient. Now two ships with a mirror each and accelerating away from each other is a much more efficient form of propulsion because they suck the wavelength (energy) out of the light. This is exactly what the 2nd example I gave does but it doesn't have the range problems inherent of two mirrors moving far apart. In effect it relies on modifying the "effective-relativistic" mass of a photon and applying force periodically on that photon which I suspect is related to the Woodward effect on this thread. The trick is finding some method of manipulating the effective mass of a photon. Some ideas are superconductors are supposed to make photons heavy?, or maybe dielectrics slow light because momentum conserved they increase lights mass, or modifying the vacuum energy with the Casimir force could possibly make light heavier/lighter. I'm still looking for that trick.