Perpetual motion

[juan king]

I would have thought that in this day and age that someone would have invented a perpetual motion machine, to generate electricity etc.

Is it even possible?

[Blib]

Perpetual motion? That's easy. I've hooked up a wind powered light to a solar powered fan.

[SC7]

[Alex]

It's impossible.

[Gun]

In a similar vein



ETA: No, it's impossible.

[Steffan]

juan king said:

I would have thought that in this day and age that someone would have invented a perpetual motion machine, to generate electricity etc.

Is it even possible?

No.

Doubtless the physicists will tell us the detail of exactly why.

But until they do:

The second law of thermodynamics states that the entropy of any closed system not in thermal equilibrium almost always increases. It is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system. From the state of thermodynamic equilibrium, the law deduced the principle of the increase of entropy and explains the phenomenon of irreversibility in nature. The second law declares the impossibility of machines that generate usable energy from the abundant internal energy of nature by processes called perpetual motion of the second kind.
The second law may be expressed in many specific ways, but the first formulation is credited to the French scientist Sadi Carnot in 1824 (see Timeline of thermodynamics).

The law is usually stated in physical terms of impossible processes. In classical thermodynamics, the second law is a basic postulate applicable to any system involving measurable heat transfer, while i statistical thermodynamics, the second law is a consequence of unitarity in quantum theory. In classical thermodynamics, the second law defines the concept of thermodynamic entropy, while in statistical mechanics entropy is defined from information theory, known as the Shannon entropy.

So there.

[Simpo Two]

You know on QI when they get it wrong and the big siren sounds...

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

It's impossible. I know because I tried building a PM machine when I was about 13 and it didn't work, so there.



The closest thing to PM I know is Europe, where they keep plucking money from thin air and throwing it away. When Greece has spent it all (in about 12 hours) they magic up some more money and give it to them. Et repete.

[Steffan]

Simpo Two said:

You know on QI when they get it wrong and the big siren sounds...

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

It's impossible. I know because I tried building a PM machine when I was about 13 and it didn't work, so there.



The closest thing to PM I know is Europe, where they keep plucking money from thin air and throwing it away. When Greece has spent it all (in about 12 hours) they magic up some more money and give it to them. Et repete.

If you have a look at my 'The end is Nigh for the PIIGS' topic you will see we agree.

[carmonk]

juan king said:

I would have thought that in this day and age that someone would have invented a perpetual motion machine, to generate electricity etc.

Is it even possible?

There's no indication that such a thing is possible, making it very likely impossible. Besides, it's overrated. Why would a perpetual motion machine be better than, say, a wind turbine? The wind isn't likely to run out any time soon but our energy problems aren't solved by wind turbines, despite what the government would have you believe. The quantity of energy all around us is vast beyond comprehension - it's not the lack of energy that's the problem, it's the method by which it can be harnessed.

[uktrailmonster]

juan king said:

I would have thought that in this day and age that someone would have invented a perpetual motion machine, to generate electricity etc.

Is it even possible?

It's right up there with time machines and teleporters i.e. fundamentally impossible. So don't expect to see one anytime soon in our universe.

[grumbledoak]

You cannot win.
You cannot break even.
You cannot leave the table.

Few Physical theories ever get called 'Laws'

[davepoth]

uktrailmonster said:

It's right up there with time machines and teleporters i.e. fundamentally impossible. So don't expect to see one anytime soon in our universe.

Well, teleporting isn't impossible at all. Here's a paper all about it from IBM.

http://researcher.ibm.com/view_project.php?id=2862

Time travel is fundamentally possible according to the current universe model. In fact you do it every time you get on a plane albeit in a very small way.

I would say that the only thing that would certainly stop the production of a perpetual motion machine is that it would need to work for ever. Given infinite time, it's 100% certain that someone would accidentally press the stop button at some point.

[uktrailmonster]

davepoth said:

Well, teleporting isn't impossible at all. Here's a paper all about it from IBM.

http://researcher.ibm.com/view_project.php?id=2862

Time travel is fundamentally possible according to the current universe model. In fact you do it every time you get on a plane albeit in a very small way.

I would say that the only thing that would certainly stop the production of a perpetual motion machine is that it would need to work for ever. Given infinite time, it's 100% certain that someone would accidentally press the stop button at some point.

I guess I should have been more specific. By teleporting I meant moving an entire object (Star Trek style) near instantaneously from one distant point to another in one piece, not some sub-atomic particle which I agree may be possible.

By time travel I meant physically travelling back in time. You don't do that when you get on a plane, although time does slow down with increased speed. I believe it is considered by most credible scientists to be impossible to actually reverse time and re-visit the past. Maybe someone from the future will pop back and tell me I'm wrong?

[Oakey]

Do I not recall a thread from a PHer who claimed to have invented a perpetual motin machine but couldn't tell anyone how exactly because he was afraid someone would steal the idea and his fortune?

[davepoth]

uktrailmonster said:

By time travel I meant physically travelling back in time. You don't do that when you get on a plane, although time does slow down with increased speed. I believe it is considered by most credible scientists to be impossible to actually reverse time and re-visit the past. Maybe someone from the future will pop back and tell me I'm wrong?

The most credible theories involve wormholes, and for those to work properly you need to have built an exit to the wormhole. Therefore you would only be able to travel back to the point in time at which the wormhole exit was switched on.

[Simpo Two]

You can't create energy from nothing. Therefore if something is generating energy something else is being used up. Matter.

When you have converted all the matter to energy I'm not sure what's left; you can't have a warm vacuum I think..

[hairykrishna]

This is an excellent website on perpetual motion devices. The museum of unworkable devices; http://www.lhup.edu/~dsimanek/museum/unwork.htm

[Squirrelofwoe]

My rudimentary understanding of these creations was that it was possible in some cases to build a closed system that, in a vacuum, would continue cycling indefinately- however once any attempt was made to 'harness' this energy from outside of said vaccum (to have any useful application), the required external contact would (even marginally) overcome the energy output of the system and ultimately, bring it to a halt.

However, as I did my A-levels about 9 years ago (and I dropped Physics halfway through!) the above theory is likely as water-tight as a sieve...

[Nimby]

http://www.youtube.com/watch?v=Xy0UBpagsu8

[R300will]

Simpo Two said:

You can't create energy from nothing. Therefore if something is generating energy something else is being used up. Matter.

When you have converted all the matter to energy I'm not sure what's left; you can't have a warm vacuum I think..

You cannot create energy, you can convert energy to matter and vice versa but you need the 'higgs boson' assuming it exists. As for time travel can the worm-hole thing work?