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Old 13th November 2012, 01:48 AM   #1
Squeegee Beckenheim
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Lawrence Miles' perpetual motion machine

For those of you who don't know, Lawrence Miles is an author, chiefly of Doctor Who spin-off books. He's a divisive figure in fandom, but most people are generally agreed that he is, at least, a very intelligent man. In a recent blog of his he's outlined his idea for a (purely theoretical, as the technology to build it doesn't yet exist) perpetual motion machine. Here's the basic outline:

Quote:
Six years ago, I designed a perpetual motion machine of my own. I didn't actually set out to do this: I was watching a documentary about water wheels (look, I'm Homo BBC4, all right?), and found myself niggled. Two sets of facts, both of which had been explained to me as "true", seemed to contradict each other. The result apparently went against Maxwell's equations, so something was clearly wrong somewhere.

My machine was purely theoretical. It couldn't be constructed on present-day Earth, because it relies on the ability to artificially engineer wormholes. But nobody's ever proved that to be impossible, and if Carl Sagan can accept it as the basis of an argument, then I'm sure you can.

Here's the diagram. And I've already copyrighted it 2006, so hands off.



It's really very simple. The core of the device is a vertical tube, within the gravitational field of a planet (or any other sizeable body). A projectile, let's just call it a metal ball, is dropped into the tube. It turns the "water wheel", and the energy is stored in whatever medium suits you. After that, the ball falls to the bottom of the tube and enters your wormhole. The wormhole has been arranged, and space-time carefully folded, so that the "exit" of the wormhole is at the top of the tube. Travelling from bottom to top without actually being lifted, the ball begins its journey again. The wheel keeps turning. Infinite energy is produced.

No, I couldn't see the problem either. But I'm one of the half-learned.

The obvious difficulty - I say difficulty, not flaw - is that entropy strikes at the heart of the machine. The ball will wear down the wheel; the machinery will fall apart. But this ceases to be a problem when you realise the vast amounts of energy being produced out of nowhere, more than enough to fuel a self-repair system. Vast energy permits the replacement of matter, so it's an engineering problem, not a problem with the physics. (And if you're prepared to countenance the wormholes, then something clever involving nanites is probably going to be on the cards.) This aside, it all looked moderately rational.
So, if there's a problem with the physics - what is it?
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Old 13th November 2012, 02:06 AM   #2
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I'm going to hazard a guess that it's all down to the physics of this mythical engineered wormhole. I mean, that's the bit that seems to be made up.
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Old 13th November 2012, 02:06 AM   #3
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LOL...how much energy is required to open and maintain the wormhole? I am going to guess its a tad more than the output of a metal ball striking a water wheel with the force of gravity.
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Old 13th November 2012, 02:49 AM   #4
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Before even thinking about how gravity would look in that made-up "tube" -

- surely the first problem is the massive royalty payments that would be due to the authors of the video game "Portal"?
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Old 13th November 2012, 05:24 AM   #5
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Originally Posted by Tolls View Post
I'm going to hazard a guess that it's all down to the physics of this mythical engineered wormhole. I mean, that's the bit that seems to be made up.
A wormhole is a theoretical construct which is consistent with relativity. Carl Sagan and Stephen Hawking both seem to think/have thought that construction of them was a theoretical possibility. So, not entirely "made up".

Or are you saying that this thought experiment utterly precludes the idea of artificially creating a wormhole? If so, can you explain how?
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Old 13th November 2012, 05:24 AM   #6
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Terry Pratchett mentioned something like this in one of the Discworld books, it's by no means a new idea.
The energy being extracted from the system comes from the gravitational energy of the mass. It also doesn't take into account the energy cost of maintaining the wormholes, assuring such is possible.
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Old 13th November 2012, 05:33 AM   #7
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Originally Posted by 383LQ4SS View Post
LOL...how much energy is required to open and maintain the wormhole? I am going to guess its a tad more than the output of a metal ball striking a water wheel with the force of gravity.
I'm sure it would take a lot of energy to create a wormhole. I'm not sure it'd take any to maintain it, although I'll defer to anyone with greater knowledge of the physics than me on that point.

But the point is that this machine could theoretically run until the universe ended or the gravity source was destroyed. And there's no reason why you have to restrict your thinking to a small metal ball or just the one, or even a metal ball at all. The physical apparatus is an illustration, really, of the fact that when the ball moves from the bottom of the tube to the top that it gains potential energy for seemingly no cost.

Can we know that there's no way that such a device could make back the energy it'd take to create the wormhole and more?

Also, to quote Miles on this:

Quote:
I took it to a few of my more academically-scientific acquaintances, and asked them what the problem was.

[...]

The suggestion was [...] raised that the engineering of wormholes might in itself require infinite energy before infinite energy could be generated, although if you're going to assume that the universal rules re: the warping of space-time have been deliberately fixed in order to protect the Laws of Thermodynamics, then you might as well just write GOD SAYS NO on the diagram.
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Old 13th November 2012, 05:34 AM   #8
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Originally Posted by WilsonG View Post
Before even thinking about how gravity would look in that made-up "tube" -

- surely the first problem is the massive royalty payments that would be due to the authors of the video game "Portal"?
Lawrence says this is Copyright 2006, whereas Portal came out in 2007. So it could be the other way round.

You could mention Narbacular Drop, but that was magic, rather than physics.
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Old 13th November 2012, 05:36 AM   #9
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Originally Posted by catsmate1 View Post
Terry Pratchett mentioned something like this in one of the Discworld books, it's by no means a new idea.
The energy being extracted from the system comes from the gravitational energy of the mass.
To give Lawrences answer to this (which was actually the little bit I cut out of the quote above):

Quote:
Among other things, [my more academically-scientific acquaintances] speculated that the gravity would in effect "run out": a difficult proposition for me to grasp, given that every model for gravity I've seen (or do I mean metaphor for gravity...?) has presented it as a side-effect of the nature of space-time, not a finite quantity. I couldn't really worm a de-vagued version out of anyone, and my elementary research into gravitational potential energy didn't help much.
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Old 13th November 2012, 05:38 AM   #10
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I don't want to end up quoting the whole blog, and I suggest people read the whole thing for the machine in context, but let me just add this bit:

Quote:
There are two notable points here, which between them mean that the Wormhole Water Wheel has done its job, at least as a personal thought-experiment. Firstly: though I still don't know exactly what's wrong with it, it doesn't immediately look stupid to people who know a lot more about physics than I do, which is more than you can say for most perpetual motion machines. Secondly: it's raised questions in my own mind about the very nature of "stupid", and the way sentimentality - or, if you prefer, basic human need - influences our sense of speculation even when we think we're being wholly scientific. More than once while I was touting my impossible machine, I was left with the sense that the explanations as it Why It Didn't Work were based on the assumption that It Can't Possibly Work, even that the universe required safety protocols to ensure its failure... meaning, they weren't exactly explanations.

A third and incidental point is that the diagram would make a really nice T-shirt.
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Old 13th November 2012, 05:43 AM   #11
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If a perpetual motion machine could exist it would have to overcome friction. Perhaps an exotic device like the one in the illustration would work but we do need a wormhole now don't we?

If it were possible to make a wormhole I'd consider it too dangerous. Whose to say a little wormhole won't become a big wormhole?
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Old 13th November 2012, 06:02 AM   #12
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Originally Posted by Squeegee Beckenheim View Post
A wormhole is a theoretical construct which is consistent with relativity. Carl Sagan and Stephen Hawking both seem to think/have thought that construction of them was a theoretical possibility. So, not entirely "made up".

Or are you saying that this thought experiment utterly precludes the idea of artificially creating a wormhole? If so, can you explain how?
By "made up" he never actually goes down the road of figuring out the energy cost of it (as pointed out later). Because I suspect if we were to look at that cost then this would be far from a perpetual motion device.

It's a little like having a childrens windmill and calling a perpetual motion device, all because you are ignoring the cost that has gone into the construction and maintenance of the bloody great turbine that's creating the wind.
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Old 13th November 2012, 06:45 AM   #13
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Originally Posted by Tolls View Post
By "made up" he never actually goes down the road of figuring out the energy cost of it (as pointed out later). Because I suspect if we were to look at that cost then this would be far from a perpetual motion device.

It's a little like having a childrens windmill and calling a perpetual motion device, all because you are ignoring the cost that has gone into the construction and maintenance of the bloody great turbine that's creating the wind.
I can only refer you to the earlier answers to the energy cost question.
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Old 13th November 2012, 06:54 AM   #14
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Originally Posted by Squeegee Beckenheim View Post
So, if there's a problem with the physics - what is it?
The problem is that wormholes are not teleportation. That is, you don't magically disappear from one place and instantaneously appear somewhere else. It's a shortcut so you can travel between two points faster than would appear possible, but you still travel through spacetime to do so. This is important because of how energy fields actually work. Your change in potential energy is due solely to the difference in potential energy between your start and end point. If you pick up a rock and put it on a shelf, it gains exactly the same amount of gravitational potential energy as if you pick it up, take it on a space flight to the Moon and then bring it back and put it on the shelf.

For this machine, that means the projectile must use up exactly as much energy travelling through the wormhole as it would if it moved outside the wormhole. It doesn't simply teleport back to the top, it travels through a gravitational field to the top and ends up gaining exactly the same amount of potential energy, and therefore losing the same amount of kinetic energy, it would have if it had taken a different path not involving a wormhole.
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Old 13th November 2012, 07:34 AM   #15
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The modern understanding of gravity is that it results from space-time being curved. The same equations can be solved in such a way that they correspond to a "tunnel" in space-time.
Unfortunately, I am not familiar with these equations. I suspect that going through the wormhole would still mean going upwards, like digging a tunnel to the top of a mountain.

That said, I googled on the conversation of energy in general relativity and lo and behold, there are issues there.
http://blogs.discovermagazine.com/co...not-conserved/
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Old 13th November 2012, 07:52 AM   #16
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Originally Posted by Squeegee Beckenheim View Post
I can only refer you to the earlier answers to the energy cost question.
But it doesn't explain it.
It simply hand waves it away.
You say it won't cost anything to maintain, but with nothing to show that would be the case.

And this is not even going into how wormholes are theorised to function.

Maybe Larry covers that, but I try and avoid his site for fear of encountering a rant.
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Old 13th November 2012, 08:06 AM   #17
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Originally Posted by Cuddles View Post
The problem is that wormholes are not teleportation. That is, you don't magically disappear from one place and instantaneously appear somewhere else. It's a shortcut so you can travel between two points faster than would appear possible, but you still travel through spacetime to do so. This is important because of how energy fields actually work. Your change in potential energy is due solely to the difference in potential energy between your start and end point. If you pick up a rock and put it on a shelf, it gains exactly the same amount of gravitational potential energy as if you pick it up, take it on a space flight to the Moon and then bring it back and put it on the shelf.
It gains the same amount of potential energy, but it certainly costs more energy to take it to the moon and back.

Quote:
For this machine, that means the projectile must use up exactly as much energy travelling through the wormhole as it would if it moved outside the wormhole. It doesn't simply teleport back to the top, it travels through a gravitational field to the top and ends up gaining exactly the same amount of potential energy, and therefore losing the same amount of kinetic energy, it would have if it had taken a different path not involving a wormhole.
So would that mean that it'd get stuck in the wormhole? Because it wouldn't have enough kinetic energy to get back to the top were there, say, a ramp at the bottom. So if it necessarily would take the same amount of kinetic energy to get to the top again, then it couldn't reach the top. The gravity would pull it in to the wormhole (unless wormhole event horizons block gravity), and it'd travel a little way in to the wormhole through momentum, but couldn't reach the top, as there's not enough energy to carry it there.

I'm not entirely sure I see how this works. I can't believe that it must cost the same amount of energy to make a journey with a wormhole as it does without. Wormholes are often talked about with a view to travelling interstellar distances - from galaxy to galaxy, even. If there was a wormhole just the other side of the moon which led to the opposite side of the universe, would it really take as much energy to travel through it as it would to just point a rocket at the other side of the universe and let it travel on for trillions upon trillions of years? That doesn't make sense to me.
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Old 13th November 2012, 08:09 AM   #18
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Originally Posted by Tolls View Post
But it doesn't explain it.
It simply hand waves it away.
That's because it doesn't seem to actually address the point in any meaningful way but is itself just hand-waving the perpetual motion machine away.

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You say it won't cost anything to maintain, but with nothing to show that would be the case.
Please quote where I said that.
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Old 13th November 2012, 08:16 AM   #19
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Originally Posted by Squeegee Beckenheim View Post
For those of you who don't know, Lawrence Miles is an author, chiefly of Doctor Who spin-off books. He's a divisive figure in fandom, but most people are generally agreed that he is, at least, a very intelligent man. In a recent blog of his he's outlined his idea for a (purely theoretical, as the technology to build it doesn't yet exist) perpetual motion machine. Here's the basic outline:



So, if there's a problem with the physics - what is it?
The machine is not perpetual, it will require to take energy from somewhere, and in this case the gravity field of the planet slowing it down until it spirals into the sun. or something similar. It would be awfully long so.
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Old 13th November 2012, 08:17 AM   #20
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Don't most planetary masses (like the one in the diagram) move in space? And aren't wormholes theoretically supposed to be, well, anchored somehow?

I am vastly ignorant of all things physics (so contrarily I love threads like these), so forgive me if my question re: the OP is foolish.
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Old 13th November 2012, 08:17 AM   #21
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Originally Posted by Squeegee Beckenheim View Post
For those of you who don't know, Lawrence Miles is an author, chiefly of Doctor Who spin-off books. He's a divisive figure in fandom, but most people are generally agreed that he is, at least, a very intelligent man. In a recent blog of his he's outlined his idea for a (purely theoretical, as the technology to build it doesn't yet exist) perpetual motion machine. Here's the basic outline:



So, if there's a problem with the physics - what is it?
It will cease to operate a good bit before the Heat Death of the Universe. thus not Perpetual, merely long-lived (if it works at all). There may be more as this is not my specialty.
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Old 13th November 2012, 08:27 AM   #22
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Originally Posted by Squeegee Beckenheim View Post
I'm not entirely sure I see how this works. I can't believe that it must cost the same amount of energy to make a journey with a wormhole as it does without.
Sounds like you'd have to boost something to escape velocity to get it through the lower mouth of the wormhole. Things could simply fall through from the upper mouth.
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Old 13th November 2012, 08:29 AM   #23
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I suspect, from a position of blissful ignorance, that there may be some problem with a wormhole existing within a strong gravitational field.

Either that or the fairies will just nick the balls.
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Old 13th November 2012, 08:30 AM   #24
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Originally Posted by Squeegee Beckenheim View Post
A wormhole is a theoretical construct which is consistent with relativity. Carl Sagan and Stephen Hawking both seem to think/have thought that construction of them was a theoretical possibility. So, not entirely "made up".

Or are you saying that this thought experiment utterly precludes the idea of artificially creating a wormhole? If so, can you explain how?
I doubt he is saying that, and if he were, neither he nor I are Sagan or Hawking - but
neither are you nor Mr. Miles. OR: since a thought experiment means just as much as the paper it is written on (not much usually), it is simply mental masturbation until/unless a technology capable of producing the parts and assembling them without mishap shows up. I have not noticed such in my recent adventures in scientific literature or other media.

Please note, I am not trying to be nasty (if you check my posts in certain politics threads you will more deeply and fully understand that) - it is simply observation that many people with limited knowledge of physics try to find ways to overcome basic physical laws. I have no knowledge of any that have succeeded - and strong knowledge of many who have tried and failed to do so (or, in fewer cases have faked and appeared to succeed until their trick was found out).
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Old 13th November 2012, 08:32 AM   #25
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Originally Posted by Squeegee Beckenheim View Post
Please quote where I said that.
Originally Posted by Squeegee Beckenheim View Post
I'm sure it would take a lot of energy to create a wormhole. I'm not sure it'd take any to maintain it, although I'll defer to anyone with greater knowledge of the physics than me on that point.
With no reason to say why.

So we have the start up cost which is unkown, and the maintenance cost which is unknown, and somehow this is a perpetual motion machine.

And then we have the physics stuff brought in by other posters.

So no, Larry has not shown that this would be a perpetual motion machine. Anymore than my windmill is.
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Old 13th November 2012, 08:37 AM   #26
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Originally Posted by 3point14 View Post
I suspect, from a position of blissful ignorance, that there may be some problem with a wormhole existing within a strong gravitational field.

Either that or the fairies will just nick the balls.
Not mine!!!!!Please'n'thank you!!
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Old 13th November 2012, 08:43 AM   #27
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Originally Posted by Cuddles View Post
The problem is that wormholes are not teleportation.
This is the answer, folks. If the worm hole connects to locations with very different gravitational potentials, then it will take work to push an object through the wormhole, the same amount of work you would get from letting the object drop from the high potential end to the low potential end. So if it starts at the high potential end and drops towards the low potential end, and you extract some of the kinetic energy from the object en route, then it won't pass through the wormhole, it will just stop at the bottom.
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Old 13th November 2012, 09:12 AM   #28
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Even if this worked, how would it be fundamentaly different than having a solar powered device that ran until the sun burned out?

Is there some larger power field to tap, that lasts forever?
If perpetuity can't exist, than its a matter of degrees of perpetual.

Too bad about all the space junk. A pv panel in orbit would have a good chance of doing work for a very long time.
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Old 13th November 2012, 10:14 AM   #29
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Originally Posted by Aepervius View Post
The machine is not perpetual, it will require to take energy from somewhere, and in this case the gravity field of the planet slowing it down until it spirals into the sun. or something similar. It would be awfully long so.
See where this is addressed above.
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Old 13th November 2012, 10:16 AM   #30
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Originally Posted by Tolls View Post
With no reason to say why.
And no reason to say why not, either. Unless you have one.

..it's also not what you said I said.

Quote:
So no, Larry has not shown that this would be a perpetual motion machine. Anymore than my windmill is.
I think you should probably read the rest of the blog.

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Old 13th November 2012, 10:20 AM   #31
Squeegee Beckenheim
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Originally Posted by quarky View Post
Even if this worked, how would it be fundamentaly different than having a solar powered device that ran until the sun burned out?
Because that's capturing energy that the sun is producing in a nuclear reaction. The machine would be using the potential energy of an object a distance away from a large mass. Despite what a couple of people have said in this thread, gravity is curvature of spacetime, and not something that the energy will be drained from. Gravity will not run out, unless this process somehow eliminates mass from the planet.
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Old 13th November 2012, 10:32 AM   #32
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Originally Posted by Squeegee Beckenheim View Post
And no reason to say why not, either. Unless you have one.

..it's also not what you said I said.
Well, you did hedge it I suppose, but still...
I don't need a reason...the person coming up with this needs to explain how. Since Larry's not here and you seem to be playing spokesperson, that I suppose implies you.

For the same reason I wouldn't expect you to explain why it's incredibly unlikely that I have a holiday home on Mars that I take my summer hols at each year.

Originally Posted by Squeegee Beckenheim View Post
I think you should probably read the rest of the blog.
Believe me, I have a weak constitution for Larry's ramblings...I try and avoid them when at all possible.
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Old 13th November 2012, 11:20 AM   #33
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Originally Posted by Squeegee Beckenheim View Post
And no reason to say why not, either. Unless you have one.
Tolls may not have a reason, but I do. It's the same reason Cuddles explained. The idea will not work
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Old 13th November 2012, 11:23 AM   #34
Squeegee Beckenheim
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Originally Posted by Tolls View Post
Well, you did hedge it I suppose, but still...
I said what I said, because that's what I meant.

Quote:
I don't need a reason...the person coming up with this needs to explain how. Since Larry's not here and you seem to be playing spokesperson, that I suppose implies you.

For the same reason I wouldn't expect you to explain why it's incredibly unlikely that I have a holiday home on Mars that I take my summer hols at each year.
Yeah, you really need to read the rest of the blog.

Quote:
Believe me, I have a weak constitution for Larry's ramblings...I try and avoid them when at all possible.
...which is why you seem to be talking as if the blog is saying something it isn't.
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Old 13th November 2012, 11:26 AM   #35
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Originally Posted by Ziggurat View Post
Tolls may not have a reason, but I do. It's the same reason Cuddles explained. The idea will not work
Well, firstly, Cuddles didn't say anything whatsoever about wormholes requiring energy to remain open. And, secondly, I've already addressed what I see as problems with Cuddles' explanation and am waiting for a reply to those. It doesn't have to be Cuddles who addresses them, you can if you like.
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Old 13th November 2012, 11:44 AM   #36
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Originally Posted by Squeegee Beckenheim View Post
Well, firstly, Cuddles didn't say anything whatsoever about wormholes requiring energy to remain open.
First: we don't know whether wormholes require energy to stay open. Second: it doesn't matter for the purposes of this question. The idea doesn't work even if the wormhole is a simple, stable, eternal object that was given to you for free.

Quote:
And, secondly, I've already addressed what I see as problems with Cuddles' explanation and am waiting for a reply to those. It doesn't have to be Cuddles who addresses them, you can if you like.
Imagine you're trying to drive up Pike's Peak. You're on the main mountain road, creeping around hairpin switchbacks, and complaining about how hard your car has to work to go uphill. Suddenly, a highway patrolman shows up and opens the gates to the secret fire road. "It follows the ridge and skips the switchbacks", he says. Then a tunnel-boring machine pops out of the mountainside; a sandhog climbs down and says "I just bored a tunnel straight to the top, it's even shorter than the fire road." They're shortcuts.

I propose a perpetual motion machine: you will haul a heavy weight to the top of Pike's Peak via the tunnel, then roll it back down via the long main road. Is that a source of infinite energy? No.

Wormholes are like that. They'd offer paths from A to B with very short travel time, but they don't avoid the gravitational-potential-difference between A and B. If you had a wormhole leading from sea level to the top of Pike's Peak, traversing the wormhole would feel like a short but ultra-steep uphill climb.
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Old 13th November 2012, 11:55 AM   #37
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Thermodynamics can be such a Debby Downer sometimes.
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Old 13th November 2012, 12:04 PM   #38
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Originally Posted by Squeegee Beckenheim View Post
It gains the same amount of potential energy, but it certainly costs more energy to take it to the moon and back.
When a rocket is launched, it gains kinetic and potential energy from the chemical energy released when fuel is burned. At the same time this chemical energy is also transferred to heat and other forms of energy that go to other effects than the one we're interested in (moving the rocket).
The energy is conserved, but the entropy increases.
It is this waste of energy that means going to the moon and back "costs more energy".

Quote:
The gravity would pull it in to the wormhole (unless wormhole event horizons block gravity), and it'd travel a little way in to the wormhole through momentum, but couldn't reach the top, as there's not enough energy to carry it there.
What we perceive as gravity results from the curvature of space-time, or at least that's what general relativity tells us. Wormholes are a prediction, sort of, of the same theory that explains gravity. Event horizons are due to gravity.

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I'm not entirely sure I see how this works. I can't believe that it must cost the same amount of energy to make a journey with a wormhole as it does without. Wormholes are often talked about with a view to travelling interstellar distances - from galaxy to galaxy, even. If there was a wormhole just the other side of the moon which led to the opposite side of the universe, would it really take as much energy to travel through it as it would to just point a rocket at the other side of the universe and let it travel on for trillions upon trillions of years? That doesn't make sense to me.
Traveling does not take any energy at all. A moving object has kinetic energy. It will just keep moving until it loses that energy at some time.
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Old 13th November 2012, 12:10 PM   #39
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Do wormholes lack mass? If so, I could see this working. Otherwise, your ball is going to have to somehow power itself away from the upper wormhole. It seems like the amount of energy used to escape the upper wormhole would equal if not exceed the energy gained by falling into the lower one.

As an aside, I have recently perfected an overunity device, the details of which are too simple to explain herein.
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Old 13th November 2012, 12:23 PM   #40
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So where do we get a million light year length of power cord and a very big switch
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