Yesterday I was reading the lovely blog of Mr Lawrence Miles, because he’s always good for a laugh or a crossly-worded diatribe.
For those of you who are not ming mongs, Mr Miles is a gentleman of the crabby and outspoken persuasion who has written some rather excellent Doctor Who novels, and who co-authored About Time, a Doctor Who guide so compendious that it makes The History of the Decline and Fall of the Roman Empire look like Listverse’s Top Ten Whacky Romans.
I found Mr Miles musing about wormholes and perpetual motion machines. Now, dear Lawrence does like to hear the sound of his own fingers typing, but I can’t criticise him for that, particularly when he muses so charmingly about the history of scientific thought and entropy. As I often do, I suggest you may wish to read the whole thing.
We can be sure, at least, that wormholes work. Which is to say, we can be sure we won’t look stupid if we bring them up in conversation. We know this because Carl Sagan told us so. Needing a way to bring humans and aliens into Contact, and not wanting to resort to anything silly like spaceships travelling faster than light in real-space, he concluded that the most feasible method of travelling bbbillions and bbbillions of miles in order to meet one’s own dead dad was to interpret General Relativity in a rather dynamic way. This idea wasn’t new, and the w-word had been used by a rather apologetic John Wheeler in the ’50s, but it’s informed every generation of nuts-and-bolts sci-fi since 1985. Nobody has yet proved wormholes impossible. In theory, they’re still the fastest way to get from A to A-but-on-the-other-side-of-space.
Note the sentiment buried in that logic, though. It’s a sentiment – perhaps in more than one sense of the word – that’s found even in Sagan’s own musings. Not wanting to resort to anything silly like faster-than-light travel. Current Scientific Thinking is an awkward, chimerical thing, always slippery, always mutable, but mutable in surprising ways. Thankfully, and despite the best attempts of creationists to suggest otherwise, it’s well aware of its own nature: yet even so, there are principles for which even the most flagellantly self-analytical physicist feels an attraction stronger than reason. You don’t mess with the speed of light, even if the Standard Model is incomplete. And you don’t try to outwit the Laws of Thermodynamics, especially not the second one.
The thing I particularly wanted to point out, because I suspect you lot would enjoy it, is Mr Miles’ proposal for a perpetual motion machine.
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.
Given my background, however, it seemed… a little unlikely that I’d found a way of punching entropy in the face.
Have at it. My immediate thought (and I stress that my book learning on science is pretty much restricted to what you get from Doctor Who novels and Buffy, so I believe all sorts of weird shit) was that the machine works (if it works) because it is not, in fact, a perpetual motion machine (assuming we define perpetual motion as motion that continues indefinitely without any external source of energy), so much as a way to harness gravity on an ongoing basis.
The ball is in free fall and continues to accelerate at a constant rate due to gravity (assuming (again) a uniform gravitational field). The machine captures energy from the ball roughly equal to the amount of the acceleration when hits the waterwheel, and siphons it off to run flying cars and time machines.
So while the machine might run until gravity runs out, it can’t run perpetually and would be extinguished, as us all, in the final heat death of the universe.
[Image copyright: Lawrence Miles]
ArchTeryx
It’s not a true perpetual motion machine, of course. It’s not just the forces of friction and wear; you also have to put in the energy required to create the wormhole. If the machine can effectively produce an infinite amount of energy with little input, then it probably would take an infinity of energy to create the wormhole to power it.
In other words: the profit margin is awesome, but the startup costs will SLAUGHTER you.
It does make an awesome physics thought experiment, though. Tell the student that the creation of the wormhole will take Xx10^100 joules, and calculate how long the machine would have to work to break even!
Old Dan and Little Ann
Wormholes fascinate me. I don’t fucking understand them but I’ve given it my best effort to read about them over the years. I clicked on the link, too. Is it just me or does having a website with all black background and white font awful?
PeakVT
… and would be extinguished, as us all, in the final heat death of the universe.
Well, that sounds like a bummer. But as long as it happens after November 6, I won’t be too mad.
eemom
Eleventy-five! Let’s hear it for a 1:1 Post Comment ratio!
Sarah, Proud and Tall
@Old Dan and Little Ann:
It’s not just you.
Chet
Potential gravitational energy, such as the additional energy the projectile has at the top of the tube, is path-independent because gravity is a conservative force. So the wormhole is either supplying energy to the projectile to get it back to the top of the tube (in which case the device returns energy under-unity), or the projectile comes to a rest at the mouth of the wormhole at the bottom of the tube (because it doesn’t have the energy to enter it.)
Sorry, not a perpetual motion machine.
The Dangerman
I was hoping for String Theory (we were promised Physics or Eye Candy; strings would have worked for either, doncha know, though I’m not sure what theory would be involved with a String Bikini).
aangus
http://www.youtube.com/watch?v=anjT71N4PGM
Jack the Second
The most disturbing thing with this configuration is the equal-and-opposite.
As the metal ball is pulled towards the Earth, the Earth is pulled towards the metal ball. If the metal ball can’t move (because it keeps falling in the wormhole, the Earth must…
Albert
First of all, the idea of a perpetual motion machine isn’t that it lasts forever; it’s that it creates a net surplus of energy in a closed system. In other words, it creates energy out of nothing. If the concept described does that within whatever the mathematical model of a wormhole is, it would become a strong argument against that model of a wormhole. Otherwise, it would so change our concept of what the universe is, it would make wormholes seem like a silly diversion.
redshirt
Yeah, cool idea, but it breaks when you consider what energy is necessary to create the wormhole, or even shape the wormhole in this configuration. Lots o’ energy.
aangus
Or, as we say in Canada…
:))
http://www.youtube.com/watch?v=Kw54-rCIrPs
max
Pardon moi: WOO HOO! Go O’s!
max
[‘This is an old notion, I think, since I have heard it before but cannot remember where.’]
PeakVT
@max: That was a good game. I got a little nervous in the last inning, but I never had that sinking feeling. Now the O’s get a chance to FTFY.
Brother Shotgun of Sweet Reason
@max: WOO HOO INDEED!!!
Now, on to FTFY!
And!
Yeah, even assuming zero-energy wormholes, this is just using the Earth as a huge gravity battery. Every trip pulls the Earth a little closer to the device, and considering what’s involved, I don’t want to know how that ends. Plus, if we’re treating a wormhole like a shared fixed point in time space, the Earth… Isn’t. You get one shot at this and then the solar system flies away in its galactic and solar orbit. If you say you can tether this wormhole device in the orbit of something moving so fast through space and time, well now that’s a little silly.
Paladin
That was Larry Niven’s “Theory and practice of teleportation”. Look it up. Not only you get “free” energy, you can actually build a planetary engine – that is, an engine that moves planets.
If only wormholes would work, and we could build them…
Peter
Larry Niven indulged in a few similar thought experiments regarding teleportation in an essay published in one of his collections of short stories, All the Myriad Ways. It had a notion similar to this one, as well as thoughts on teleporting space ships and the hazards thereof.
Yutsano
@PeakVT: Obot.
aangus
http://www.youtube.com/watch?v=nm1tlIcxNeg
gnomedad
Now you’re thinking with portals.
(Shorter, less impressive, with cat.)
TG Chicago
To reduce wear and tear on the water wheel, then instead of a metal ball, perhaps we should use… um… water.
scav
Oh dear. Not only are my mings not monged, I don’t know where they are nor where I can have them upgraded or burnished or whatever is involved. Should I be more concerned, embarrassed, frightened or buried decently as utterly unworthy?
aangus
http://www.youtube.com/watch?v=7FdWPeHFAMk
mdblanche
Before coming to any firm conclusions about this device, I would like to hear an assessment of it from Maxwell’s Demon.
The Goo From Space
The main problem I can think of is that the wormhole itself has mass, and would fall toward the core of the planet. Some amount of energy would be required to keep it aloft.
The other thing is that any naturally-falling object might actually go to the side in the system you show. I’m thinking about this, and I keep going back and forth on it.
Think of a railgun: it pushes a slug through because the magnets are turning on in sequence, at the same time, repelling the slug in a certain direction. If you set permanent magnets up in a railgun-like arrangement, you won’t even be able to get an object to stay between the rails without forcing it in; this is why permanent-magnet railguns can’t provide free energy. The system reaches conservative equilibrium, and works to preserve it.
The same is true of this system, in a different way. I think.
Basically, I’m thinking that gravity would traverse through the wormhole itself: the hole at the bottom, where there’s planetary gravity, would end up providing a gravitational pull to the wormhole at the top. These would equal out until gravity is greatly reduced, or even completely negated, in the downward direction toward the planetary mass.
The net effect is that we get a conservative field where objects either A.) lose all their potential energy in the middle, being pulled from two different directions, and simply float there, or B.) fly off to the side, outside of the path of the two wormholes, and back into a normal gravitational field on the planet. I’m not sure which. Intuition tells me A, but when I think about it, the idea of gravity-as-a-curve-in-space-time tells me B. But I might just be misunderstanding it.
Either way, the important thing is that you’re going to have to spend energy to keep the metal ball in the path through the water wheel and back into the wormhole at the bottom, or turn the wormholes on and off repeatedly to keep the system working.
gnomedad
@Albert:
Nicely put.
Actually (and rather pointlessly), reasoning from the wormhole-in-a plane analogy, one would expect to be able to enter the wormhole from any direction and emerge from the corresponding (though mirrored) position on its twin. So the gravitational “flux” might be channeled through (part of?) the wormhole leaving the object we hoped to extract energy from floating in between.
Yes, this is nonsense. :)
FormerSwingVoter
After reading this post, I might want to have your babies.
Radio One
Getting lost in the weeds in a Doctor Who debate is just bad form, so I’ll just say that Mitt Romney losing the week again with Big Bird and the jobs numbers is amazing. I think Obama does better in a town hall debate than Romney.
Loneoak
Cease your witchery heathen! God has made but one source of infinite energy, and it is offshore drilling. Drill baby drill!
patrick II
That there will be no perpetual motion machines at ultimate peak entropy is a trivial subset of there will be no anything at ultimate peak entropy.
Tissue Thin Pseudonym (JMN)
@FormerSwingVoter: You both want to have her babies and you don’t. You won’t have have a definite opinion on the matter until after the relationship has been consummated.
piratedan
http://www.youtube.com/watch?v=9qgFGqJz9yc
Just Some Fuckhead
What happened?
Odie Hugh Manatee
I performed my own bit of science tonight by bleaching and then dyeing my wife’s hair bright pink for Boobie Month. Ok, half of her hair. Half black and half pink, to be exact. From behind and just above her ears to her neckline, vivid pink. Everything else is black.
Looks great, she loves it and the best part is that her hair didn’t burn off!
TenguPhule
No, this wouldn’t work. The flaw here is the assumption that graviational force is pulling the ball down, but if its placed so that the wormhole is directly under it, there is no direct gravitational force exterting an effect as the bottom of the “hole” is not in fact connected to the planet’s gravity well but exists as an independent dimensional body. The only energy carried would be by the person who throws the ball through the hole. “Down” for the ball is relative as Ender’s Game, pointed at the gate.
Ben Lehman
Hi! I have some GR training. Not really enough to answer wormhole questions, but hey. What’s the internet for if not ill-informed waiving about of an ill-used science degree?
My understanding is that, if there was a stable wormhole, the energy to traverse it would be equivalent to the difference in gravity potential.
In less technical language: traversing the wormhole requires going “uphill” the same amount that the ball bearing falls “downhill.”
Central Planning
My kids like to think they can come up with perpetual motion machines. I’ve had to disabuse them of their notions many times.
Fucking wormholes, how do they work? Maybe my 15yo who wants to be an astrophysicist will figure them out.
Matt McIrvin
I think Ben Lehman is right. But it would work in the world of Portal, as gnomedad said.
Colin Roald
@ArchTeryx: @ArchTeryx: I am impressed that someone who knows what they’re talking about got comment #1.
Matt
Putting on my Real Physicist hat for a second (BS, 1999), here are some issues with the machine:
– the known solutions for traversable wormholes require “exotic matter” to be stable; such material essentially has a negative energy density and correspondingly is *repelled* by normal matter gravitationally. There’s only a vague theoretical hint that quantum gravity might allow such a thing to exist.
– moreover, it require a VAST amount of exotic matter; type-III-civilization-levels, in fact: http://chandra.harvard.edu/resources/faq/black_hole/bhole-4.html
– another valuable discussion of the scales required: http://arxiv.org/pdf/0809.0907.pdf (Visser has done a lot of work with wormholes / warp drives / etc)
– assuming we can create the necessary structure, it’s still made of mass-energy, exotic or not. So we’ll have to hold it UP (or down, possibly) in the gravity field, and that could get exceptionally tricky…
– as others have noted above, there’s the problem of the force exerted by the falling objects on the planet. Sure, it’s only a tiny acceleration, but it goes on *forever* – check out the stuff NASA’s been doing with ion drives for an example of what this can accomplish.
– finally, it’s pretty straightforward to demonstrate that, if you’ve got a traversable wormhole, you’ve also got a TIME MACHINE. http://en.wikipedia.org/wiki/Wormhole#Time_travel
bruinseattrojans
Why was the title of this post not, “Wheel in the sky keeps on turning…”???
Golden opportunity, missed.
Nerull
@And!: You can’t treat it as a fixed point in space because there is no such thing as a fixed point in space.
Tonal Crow
@Chet:
Ding ding ding ding!
beingreleased
Here’s my problem with worm holes. If you crush something to a singularity on one side, how do you uncrush it at the other?
KT
The only way that machine works is if the wormhole requires zero energy to keep it open. Not really versed in wormhole theory, but intuitively, it seems like creating and keeping a wormhole stable long term would require some pretty exotic physics requiring huge amounts of energy.
Just thinking out loud…
moops
planet moving or “no fixed point” are all red herrings. You can pose the problem with the wormholes and wheel mounted on a rig that is attached to the planet, and moving in that frame. You can tune the resistance (electric load on generator) so the ball lands in the bottom hole at the same speed every time.
Over time the planet will be moving, and the generator creating free energy.
path-independence requires as an axiom “no wormwholes”, expressed as the “closed-path” requirement. Wormholes involve lifting the pencil. so you can’t use it here.
It doesn’t matter how much initial energy it takes to set up the wormwhole. That just sets the amount of time I need to break even, then from then on, free energy.
So, the simplest consistent theory I can imagine is “there is a cost to move the ball from the one end of the wormhole to the other that is *at least* the difference in potential energy at either end of the trip”
The Other Chuck
I believe wormholes as they’re currently theorized to exist (maybe) is that they’re effectively “serial devices” that only output information in a stream of particles. To say anything traveling through a wormhole would be “spaghettifiled” is a serious understatement. You might get there, but not in one piece to say the least.
moops
@The Other Chuck:
doesn’t really “matter” if the matter is coherent. a scrambled mass will still result in a perpetual motion machine unless you add something to the view of how they can work.
so, there is some cost to traversing the wormhole that is larger than the potential energy difference. unless removing information is the cost. Does the wormhole evaporate when it translates an object ? Is there a holographic explanation that thwarts this demon ?
Sarah, Proud and Tall
I love you all.
smike
Couldn’t the issue of the ball’s action on the earth be countered by properly positioning a mass on the other side of the earth?
And if you are folding back in time (via the wormhole), once you drop the ball it reappears at the top of the tube in the past. The logical problem for me is that the ball dropper would always arrive to find that the ball has already been dropped.
Warning: my reasoning is probably flawed.
Also, too, the universe may not be logical.
Ed Drone
If gravity works (and some above question that), you’d better make sure the energy removed by the “water wheel” is exactly calculated to match the acceleration of the ball, else it either arrives at the exit wormhole going slower each “round,” and eventually stops, or arrives going faster each time, in which case it becomes a dangerous projectile, eventually demolishing the “water wheel” and gathering mass as its speed approaches that of light.
You’d get all kinds of issues in that case, and, since this only works if the wormhole is maintained by less energy than you get from the waterwheel (if it takes more energy than it creates, you ain’t got no “free energy” anyway), if you shut off the machine at a certain point, the ball goes flying in the last known direction at infinite speed. Talk about a “rail gun!”
Larry Niven’s articles about this are fascinating, and highly recommended (by me, of course).
Ed