|
|
Post by Progenitor A on Oct 15, 2011 7:52:25 GMT 1
Are these possible?
Do any examples exist?
|
|
|
|
Post by principled on Oct 15, 2011 9:10:17 GMT 1
Nay I think that the invention of a PM machine has mesmorised man for over 1000 years. There are plenty of examples/ideas going back, but me thinks that none are truly PMs, if the work at all. But to state that PM machines are not possible under any circumstances would mean that there is nothing in physics we don't know. That's a big statement. I think the best thing we can say is that our current knowledge suggests that PM not possible. On a lighter note, I came across this website that categorises PM machines and explains why they will not work. The ingenuity of some designs is truly remarkable. The site is worth a quick look. www.lhup.edu/~dsimanek/museum/unwork.htmP |
|
|
|
Post by Progenitor A on Oct 15, 2011 9:32:40 GMT 1
Hi Principled
Is Voyager 1 (or 2) not a perpetual motion machine?
Is nor an electric current flowing in a cryogenic zero-resistance circuit not an example of perpetual motion?
|
|
|
|
Post by abacus9900 on Oct 15, 2011 9:51:57 GMT 1
Remember our big debate about the 2nd. law of thermodynamics?
This would tend to prohibit the existence of a perpetual motion machine on the grounds that any system tends towards chaos so that such a hypothetical machine would not be sustainable over time.
Voyager would be a perpetual motion machine if it did not ever have to interact with anything else in the universe which interferes with its motion.
|
|
|
|
Post by eamonnshute on Oct 15, 2011 10:20:02 GMT 1
A perpetual motion machine is one that does work without any input of energy, ie it creates energy. This is impossible because of the Law of Conservation of Energy.
A current in a superconductor does not do any work, and neither does Voyager, so these are not perpetual motion machines.
|
|
|
|
Post by abacus9900 on Oct 15, 2011 10:49:11 GMT 1
Is zero resistance actually possible, even in a superconductor? I would have thought there is always a very small residual resistance.
|
|
|
|
Post by eamonnshute on Oct 15, 2011 11:51:26 GMT 1
Is zero resistance actually possible, even in a superconductor? I would have thought there is always a very small residual resistance. In a superconductor the resistance is exactly zero, not merely extremely small. |
|
|
|
Post by Progenitor A on Oct 15, 2011 12:57:02 GMT 1
A perpetual motion machine is one that does work without any input of energy, ie it creates energy. This is impossible because of the Law of Conservation of Energy. A current in a superconductor does not do any work, and neither does Voyager, so these are not perpetual motion machines. If that is so then a Perpetual Motion machine is a misnomer Anyway, science has shown that the Conservation of energy is a fallacy, hasn't it? |
|
|
|
Post by abacus9900 on Oct 15, 2011 21:19:51 GMT 1
Well, the idea is that in any isolated system, energy can neither be created or destroyed, although it can be changed in form from, say, mechanical energy to electrical or chemical energy. In thermodynamics, a closed system can exchange energy (as heat or work), but not matter, with its surroundings. Think of trapping a piece of matter in a box; all you can do with the energy in the matter is move it about or convert it from one form to another but never create anymore or less overall. For example, water sealed in a container would not exchange matter with the outside world but could be made to turn into ice or steam by an exchange of energy with it. In this case, an exchange of energy with the outside world changes the state of the matter (water) but the energy itself is simply redistributed, not created or destroyed.
|
|
|
|
Post by Progenitor A on Oct 16, 2011 8:13:25 GMT 1
Philosphically the idea of Conservation of energy does not withstand much examination because if there always has been a fixed total of energy then there really was no creation was there?
And we are told that the universe is acelerating in expansion and we know that we cannot accelerate mass without energy so where does that energy come from and if it has always been there what the fook has it been doing idling around? I mean it is most uncharacteristic of energy to sit there idly isn't it?
Then we have cosmologists telling us that the amount of energy per unit space in the universe remains constant, so as the universe expands and new units of space are created, so energy is crated toi maintain that constancy
Nah, conservation of energy is a dead duck that has flown the coop (so to speak).
Anyway it was always a speculative law that could never be verified
|
|
|
|
Post by abacus9900 on Oct 16, 2011 9:51:22 GMT 1
It means that as the universe expands the total energy in it becomes more diffuse and eventually, if the universe keeps on expanding, it will be so spread out that it won't be able to form stars planets and so on. It'll just be a huge haze.
Don't forget that energy is pretty much equivalent to mass so that what is really happening is that the mass of the universe is continually being stretched.
Of course, we have dark energy, which is acting to push the universe further apart at very large scales but that is a new area.
|
|
|
|
Post by nickrr on Oct 16, 2011 14:44:34 GMT 1
Actually current theories propose that the total energy in the universe is exactly zero. The positive energy (mass, energy etc) is balanced by negative gravitational energy. www.astrosociety.org/pubs/mercury/31_02/nothing.htmlAs the link comments, the universe may be the ultimate free lunch. |
|
|
|
Post by abacus9900 on Oct 16, 2011 16:42:04 GMT 1
To me, the stumbling block to this idea is that the universe may have come from nothing.
I don't think we have a big enough handle on QM to really make definitive statements about where the universe did come from and there are currently competing ideas about this. Negative and positive energy might simply be a mathematically convenient way of looking at it but I'm a bit dubious about whether things are as straight forward as that.
|
|
|
|
Post by principled on Oct 17, 2011 8:42:19 GMT 1
As I understand it, the universe is expanding because the space is being "created" between all celestial bodies and as such the bodies are not moving through space..
Providing space is "nothing" then creating it requires nothing and so the laws of conservation of energy are not broken.
Now, I'm not saying I belive that, but this hypothesis does overcome the problem of what happens to celestial bodies once there is no more space for them to go though (ie the difference between a stationary car on a road which moves only because the road behind it is continually being made, as opposed to a car moving along a road that is already made and is of a fixed length).
However, if one accepts this hypothesis, then one then has to explain how "space" is created and what exactly is nothing. Uhm?
P
|
|
|
|
Post by Progenitor A on Oct 17, 2011 9:33:18 GMT 1
As I understand it, the universe is expanding because the space is being "created" between all celestial bodies and as such the bodies are not moving through space.. Providing space is "nothing" then creating it requires nothing and so the laws of conservation of energy are not broken. Now, I'm not saying I belive that, but this hypothesis does overcome the problem of what happens to celestial bodies once there is no more space for them to go though (ie the difference between a stationary car on a road which moves only because the road behind it is continually being made, as opposed to a car moving along a road that is already made and is of a fixed length). However, if one accepts this hypothesis, then one then has to explain how "space" is created and what exactly is nothing. Uhm? P Yup Quite difficult innit But do remember that all this stuff is metaphysics not physics - shall we discuss angels dancing on a pin-head? ;D |
|
