Read up to Chapter 21, commenting on chapter 2. Prediction about the physics of HP:MR.
Harry is mistaken about McGonagall’s transformation into a cat breaking conservation of energy; indeed, it seems to me that he is not really putting a lot of effort into finding an alternative explanation, but jumping straight to “Everything I thought I knew was wrong”. (Perhaps Lord Kelvin’s not the only one who gets a charge out of not knowing something; after all Harry has been wanting to do Something Big, and the more laws of physics are broken, the better!) A simple hypothesis which does not break conservation of energy: Rather than McGonagall’s human body literally turning into a cat, it is replaced by a cat-body from elsewhere in the universe. McGonagall’s human brain continues to operate in its usual fashion (while being physically elsewhere), and this is turned into cat-brain commands by an AI somewhere in the interface. No mass (hence no energy) appears or disappears, there’s just an exchange of objects.
Ah yes! You can store the whole human body in a cavity of the cat’s body, and vice-versa; lightspeed is no issue—indeed you could run the whole thing at ordinary neural speed. This might even solve the problem of how to order a cat’s body around; the Animagus in effect has a cat as an ordinary part of her body, and has learned to operate it the same way she learned to operate her human body.
One problem is the carrying-over of wounds from the animal to the human body, and vice-versa; this does not seem implied by the model, and requires additional explanation. Psycho-somatic damage? Since there a requirement for conscious control of which shape one is in, the opportunities for unconscious failure seem strong.
In fact, come to think of it, wasn’t there an experiment recently with remote-controlled rats, using plain Muggle science and electrodes in their brains? Extrapolate that forward fifty years and add those direct-to-brain conputer interfaces, and we could do something rather similar, given lots of training to get the feedback right. “When I think like this the rat goes that way...” An Animagus might learn this almost as a child learns to control its body.
Switching the material still violates conservation of energy. You could make a perpetual motion machine by creating a heat engine and switching hot water with cold water located elsewhere on the planet, for instance.
Yeah, you’re right, that that would just increase entropy faster. But what about using gravity to get the hot air or water to rise?
Hmm. If the switching requires no energy, it still seems like something is violated, but I’m not sure I know enough physics to determine what. What about conservation of momentum? Do the switched objects keep their current acceleration and speed?
The concept of switching in itself violates all kinds of fundamental assumptions in physics, so trying to think about it mostly results in nonsense. That’s if the switch doesn’t actually involve moving A to B and B to A by some path, though; if it does, you naturally pay the relevant costs to maintain conservation laws while switching.
It doesn’t have to be FTL. You could store the cat body in Magical Britain and run the communications link at lightspeed. It would look instant to a human—the speed of neuron processing would still be the bottleneck.
You’re right—and the speed-of-light delay in a straight line even through the diameter of the earth is only 42.55 milliseconds. That might be small enough not to be noticed.
Neutrinos! However by the time you’re postulating teleportation and time travel and so forth, I don’t think it’s necessary to insist on (obvious) conservation of energy in the first place.
Taking a great circle route increases lightspeed time to approximately 66.8 milliseconds. That might still be small enough to miss if you’re teleoperating from Britain a body in New Zealand, but it’s pushing the boundary. Wikipedia suggests 50 milliseconds#Latency_in_simulators_and_simulation).
Getting light to follow the curvature of the Earth without a fiber-optic cable or some other specialized medium seems difficult. Probably better to go straight through and just use a wavelength to which the Earth is transparent.
Of course the Muggle solution is a network of satellites...
Read up to Chapter 21, commenting on chapter 2. Prediction about the physics of HP:MR.
Harry is mistaken about McGonagall’s transformation into a cat breaking conservation of energy; indeed, it seems to me that he is not really putting a lot of effort into finding an alternative explanation, but jumping straight to “Everything I thought I knew was wrong”. (Perhaps Lord Kelvin’s not the only one who gets a charge out of not knowing something; after all Harry has been wanting to do Something Big, and the more laws of physics are broken, the better!) A simple hypothesis which does not break conservation of energy: Rather than McGonagall’s human body literally turning into a cat, it is replaced by a cat-body from elsewhere in the universe. McGonagall’s human brain continues to operate in its usual fashion (while being physically elsewhere), and this is turned into cat-brain commands by an AI somewhere in the interface. No mass (hence no energy) appears or disappears, there’s just an exchange of objects.
I think the “it’s bigger on the inside” phenomenon is a better foundation to build such a spell on.
Ah yes! You can store the whole human body in a cavity of the cat’s body, and vice-versa; lightspeed is no issue—indeed you could run the whole thing at ordinary neural speed. This might even solve the problem of how to order a cat’s body around; the Animagus in effect has a cat as an ordinary part of her body, and has learned to operate it the same way she learned to operate her human body.
One problem is the carrying-over of wounds from the animal to the human body, and vice-versa; this does not seem implied by the model, and requires additional explanation. Psycho-somatic damage? Since there a requirement for conscious control of which shape one is in, the opportunities for unconscious failure seem strong.
In fact, come to think of it, wasn’t there an experiment recently with remote-controlled rats, using plain Muggle science and electrodes in their brains? Extrapolate that forward fifty years and add those direct-to-brain conputer interfaces, and we could do something rather similar, given lots of training to get the feedback right. “When I think like this the rat goes that way...” An Animagus might learn this almost as a child learns to control its body.
Switching the material still violates conservation of energy. You could make a perpetual motion machine by creating a heat engine and switching hot water with cold water located elsewhere on the planet, for instance.
Without external input such a machine would eventually make the entire planet lukewarm, and run out of steam. No violation there.
You’re also assuming that the switching doesn’t require energy.
Yeah, you’re right, that that would just increase entropy faster. But what about using gravity to get the hot air or water to rise?
Hmm. If the switching requires no energy, it still seems like something is violated, but I’m not sure I know enough physics to determine what. What about conservation of momentum? Do the switched objects keep their current acceleration and speed?
The concept of switching in itself violates all kinds of fundamental assumptions in physics, so trying to think about it mostly results in nonsense. That’s if the switch doesn’t actually involve moving A to B and B to A by some path, though; if it does, you naturally pay the relevant costs to maintain conservation laws while switching.
Still FTL, but that’s a violation that’s turned up explicitly many times already.
It doesn’t have to be FTL. You could store the cat body in Magical Britain and run the communications link at lightspeed. It would look instant to a human—the speed of neuron processing would still be the bottleneck.
Although, given that there’s already stuff like time turners, it’s kinda a bit late in the game to be worried about FTL.
You’re right—and the speed-of-light delay in a straight line even through the diameter of the earth is only 42.55 milliseconds. That might be small enough not to be noticed.
Though through the diameter of the earth is not an easy way to transmit messages.
Neutrinos! However by the time you’re postulating teleportation and time travel and so forth, I don’t think it’s necessary to insist on (obvious) conservation of energy in the first place.
Taking a great circle route increases lightspeed time to approximately 66.8 milliseconds. That might still be small enough to miss if you’re teleoperating from Britain a body in New Zealand, but it’s pushing the boundary. Wikipedia suggests 50 milliseconds#Latency_in_simulators_and_simulation).
Getting light to follow the curvature of the Earth without a fiber-optic cable or some other specialized medium seems difficult. Probably better to go straight through and just use a wavelength to which the Earth is transparent.
Of course the Muggle solution is a network of satellites...