> At 8:16 a.m. on August 6, 1945, a fission weapon containing sixty-four kilograms of uranium detonated 580 meters above the Japanese city of Hiroshima, and Einstein’s equation proved mercilessly accurate. The bomb itself was extremely inefficient: just one kilogram of the uranium underwent fission, and only seven hundred milligrams of mass—the weight of a butterfly—was converted into energy. But it was enough to obliterate an entire city in a fraction of a second.
This reminded me of this quote from "Midnight in Chernobyl". Quite amazing to thing of such small amounts of mass being converted into such extraordinary amounts of energy.
Guess this is saying that the one kilogram of uranium is converted to fission products which are slightly lighter--one kilogram minus a butterfly--and the amount of energy released from this difference is e=(mass of butterfly)*c^2
Wait is that right? I thought charging a lithium battery was simply displacing electrons from cathode to anode, but the total number of electrons in the whole battery is conserved (and hence mass). Or is this converting that electric potential into an equivalent mass? Does this actually manifest as a difference on a scale?
... But the total mass of a molecule is also affected by the energy in the chemical configuration; the chemistry of the charged battery has more energy than the uncharged battery.
Yeah, this is also why an empty hard drive should have less mass than a full one. It's an immeasurable amount, but it should be there. Adding energy to a system should increase it's mass.
To be pedantic, I think you need to say "the act of writing to a hard drive adds mass". There is no reason to expect that writing a 1 or a 0 adds more or less mass; if there is a difference in energy states, it would depend on the encoding scheme.
Interesting, so in the context of this broader discussion, if you displaced 1% of electrons in your body by a centimeter, you would weigh 10x more than you did originally. (Both gravitational mass and inertial mass increase)
Assuming that you displaced all the electrons in the same direction, you'd produce a 1 cm electron cloud on one side of your body, and 1 cm of electron-deficient matter on the other side.
If you could somehow maintain that configuration, you'd have a capacitor storing an enormous amount of energy, so it makes sense that the mass would increase.
> In short, if I lost 1% of my electrons, I would not be a person anymore. I would be a bomb. A Coulomb bomb, if you will, with an energy equivalent to that of ten billion (modern) atomic bombs. Which would surely destroy the planet. All by removing just 1 out of every 100 of my electrons.
The most energy you can extract from any type of bomb would be if it was converted to energy at 100% efficiency.
70kg of mass is equivalent of 1,5GT of TNT.
So still a lot of bombs, but more like 1,5 thousand 1MT bombs and not "10 billions" of them.
I am not a physicist, but I think what this shows is physical impossibility of having 1% of your charge removed and your body still considered to be body even for an infinitesimal amount of time. To do that you would have to add so much energy to your body that just the mass equivalent of energy would have to be many times more than your body.
This is incorrect. Creating a charge gradient in a system increases its mass-energy. In this situation the potential energy is dramatically larger than the rest mass of the precharged person.
Edit in response to your edit: what it shows is that it would take an extraordinary amount of energy to cause the change.
Isn't that what I wrote? That separating the charge would be equivalent to adding potential energy basically adding to mass of your 70kg body so that it no longer is 70kg?
Yes, it takes over 70kg of "mass-energy" (e.g. mass converted to energy in nuclear fission) to remove 1% of all electrons in a person weighing 70 kg. That is not, in itself, contradictory.
Depending on how relativistically inclined you are, this may affect what you consider the weight of the person. But this doesn't really matter for the thought experiment.
> The most energy you can extract from any type of bomb would be if it was converted to energy at 100% efficiency.
Under normal circumstances, a bomb's energy is endogenous. But in the blog's thought-experiment, the energy is assumed to be exogenous. Therefore, your assumption that "the explosion is bounded by the mass of the person" doesn't apply to this scenario. Instead of TNT, imagine a rubberband.
> The most energy you can extract from any type of bomb would be if it was converted to energy at 100% efficiency.
Not true, imagine 2 positrons next to each other, the force these particle subject to accelerate to avoid each other is greater than the mass of those positrons itself.
In other words, if you can get accelerated to 0.9999c, you'll possess far larger energy than your rest mass.
We commonly refer to the energy released if the bomb explodes. If what we cared about was the relativistic mass energy of the matter, we wouldn't need to even refer to bombs. We'd just refer to the mass.
> Because of my 40 million Coulombs, the force between myself and my “image self” would be something like 10^{20} tons. To give that some perspective, consider that 10^{20} tons is just a bit smaller than the weight of the entire planet earth. So the force pulling me toward the earth would be something like the force of a collision between the earth and the planet Mars.
Unnecessarily heavy imo.
And I'm just going to say, the person you do this to might not have the scientific experience to realize that the electrons are the reason why they can't move anymore and why they've ripped a hole in the vacuum, but they'll still notice the effect, so it's inaccurate to say that they don't care.
this website goes in a cycle. electrons bad, electrons good. nobody holds a real position. the current "correct" take is a whim based on flavor-of-the-week politics.
and of course nobody here talks about the end user, or the social effects of electrons. please take some responsibility!!
Seems apt if you think that every time someone uses a transporter, they are really committing suicide with a new copy of themselves reconstituted elsewhere.
That was excellent but stopped tantalizingly short - he's on to something. He's uncomfortable about the concept of a "soul", but the idea of continuity is really interesting. It suggests that the boundary of a conscious entity is not purely physical, but must also encompass a temporal dimension. (This is a new thought for me, I'm excited by it.) It's a shame he felt icky about souls because you don't really need that baggage.
I'm not smart enough to really think it through but at a glance it seems to resolve those various tests and scenarios. In the malfunctioning teleport example (where the cell destroyer fails to fire), _both_ London Tim and Boston Tim are equally alive because they share the past: the teleport has succeeded in bifurcating their consciousness. Same with the split-brain twins (though you'd expect the results to be diminished).
I also like the start but it stop way before it get really interesting. I found Permutation City (by Greg Egan) to a great deal deeper, plus it's a nice story. I mentioned this also somewhere else in this thread. Tbh when people start with the soul concept or even mention it as a possibility, I usually stop reading because you start with some un-provable hypothesis that only adds unnecessary complexity. I've yet to run into a thought experiment that arrives at the concept of a soul through structured arguments (and not say religious arguments).
That's just it: jumping from discussions of the biological repository of consciousness straight to souls might be missing a whole big area.
These thought experiments got me thinking about how a conscious entity might better be considered as its "world line", not just its instantaneous physical embodiment. Call that a soul if you want, but there's no particular reason to.
I’d considered the situations in the article, but I do wonder - if you replace 10% of someone with identical particles then they are the same. 20%, 30%, etc then yes the same. But. 80%? Sure. Replace limbs and body and I can see that. But what about splitting the brain (as in article) where you don’t even need 50% for continuity.
But we effectively always get back the the ship of Theseus, and circling back to Trek,
Does Data have a soul? I don't know that he has. I don't know that I have. But I have got to give him the freedom to explore that question himself.
TFA talks a bit about that. The short of it is kinda as I was discussing above - if you consider the entity temporally as well as spatially, the Trigger's Broom/Ship of Theseus problem becomes moot.
If the transporter did not disassemble a person on one end, and instead just materialized a person on the other end (similar things happen a few times in Star Trek), which one of them is 'you'?
And which one do you think we should kill off once the away mission is done? Should we be as sanguine about it as Captain Janeway was about murdering Tuvix?
If we clone A, then from A's perspective we now have A-Prime. A-Prime is unaware and believes they are A, who now presumably has been killed. If anyone didn't observe this happen, then A-Prime essentially -is- A. If they did observe it, then they know that it's technically A-Prime.
So I guess the difference is being able to observe the gradual changes. It's more tricky when discussing an inanimate object like a ship that doesn't care either way.
It's funny because we have this discussion only pertaining to humans, if we were to produce a replica computer from computer-0, we'd rename it to computer-1 and that's that. It's just because humans want to name themselves we have issues, and we can't easily ascribe a human another name (it would mean rewriting the memory of the replica to remember being called something else).
Btw, we talk about replica's but that's only because we assume the process leaves an original and a copy, but that's not necessarily so, for example a photon of high energy can split into 2 photons of lower energy. We are not talking about originals and replica's there. One can imagine that our duplication process follows similar rules.
When copying or simply making 2 out of 1, for computers, both still have computer-0 in /etc/hostname so there's that... It's just that neither of the computers will complain when we change their designation at random.
This leaves me feeling weird about the destruction of an original in any copying process. The destruction during copying feels ok, but doing it afterwards feels very bad. It's like we want consciousness to be continuous in time and not necessarily in place. But why? Again, Permutation City goes into this in a nice way...
They will believe they are you, there is no further link that can change any attributes of the second you upon incinerating primary you, the person that already existed.
I can't remember who came up with this, but this realisation is made a lot more vivid if you imagine the "original" you being killed with an axe while your "teleported" you is happily unaware. I believe the videogame Soma has an analogous situation, although I haven't played it.
> Similarly, cloning would violate the no-teleportation theorem, which says that it is impossible to convert a quantum state into a sequence of classical bits (even an infinite sequence of bits), copy those bits to some new location, and recreate a copy of the original quantum state in the new location. This should not be confused with entanglement-assisted teleportation, which does allow a quantum state to be destroyed in one location, and an exact copy to be recreated in another location.
For anyone interested in this conceit, I recommend an episode of The Outer Limits called "Think Like a Dinosaur" dealing with this idea and what happens when it goes wrong.
Part of why I don't see the appeal, even if it were possible, of uploading your "consciousness" whatever that is, to extend "life." It's not you, and you're still dead.
Digital metempsychosis is an interesting religious belief. From an anthropological perspective I find it fascinating how the same old ideas get reimagined as technology changes. Feels like how the Sidhe got replaced by the Greys in the abduction racket, and so on.
Most successful migration in tech requires a time where both old and new system are running concurrently.
In terms of brain, this treat consciousness as software and brain/etc as hardware. whether said software can be modified to run on other hardware, or other hardware can be modified to run said software, is where the key's at.
The key to migration is to have a period when the same software is running on both platforms. As a single unit.
Most of the mass of an atom is concentrated in the nucleus. I don't want to dig out a calculator, but you probably couldn't easily measure the loss of 1% of your electrons.
If there's such a large voltage, would it discharge fast enough that the actual force doesn't matter that much? The extreeeeemly high force is probably commiserate with the extreeeeeeeeemly fast discharge, so you wouldn't build that much kinetic energy.
There'd still be loads of energy, definitely enough to turn you into a cloud of plasma with the 'millions of lightning bolts' he references, but that seems like it's orders of magnitude short to destroy the entire planet.
It’s a thought experiment to teach physics to students rather than a practical idea, so this scenario magically deletes all the specified electrons simultaneously without a chance for the body to discharge gracefully.
Given this wildly implausible conceit, you would explode much as they say.
How do you reconcile the two seemingly contradictory statements “it would be equivalent of getting hit by three lightnings at the same time” and “it would destroy the planet”
Lightning happens all the time without affecting the planet, I doubt a triple lightning would do more than 10x the damage of a single lightning.
To me this kind of contradiction is a sign that the initial assumption is impossible as lmilcin suggests here, and as the original author concludes at the end of the article.
EDIT: 3 million, not 3. My mistake. Thanks for pointing that out.
The only people who ask questions like this are Physics TAs and children. Both are equally intimidating. The former, because they know how students learn, and they can ask fantastical oblique questions to test basic knowledge. The latter, because they have no prejudices about physics and ask fantastical oblique questions without regard for logic.
I've wondered for a while why we don't use electrostatic forces more. Electrostatic motors and electrostatic speakers do exist but they are very rare compared to the ubiquitous magnetic types. It seems like it should be possible to make a really good electrostatic muscle for robots. I know that there has been some work in this direction like https://www.artimusrobotics.com/technology, but what makes it so much harder and less developed than regular magnetic electric motor technology?
In air, a relatively small electric field will cause electric discharges.
A magnetic field can have very large intensities without creating problems, so that is the reason why we use electromagnetic motors and not electrostatic motors.
The maximum magnetic field in a motor is normally limited by the saturation of the ferromagnetic materials at values where the density of energy in the space between the stator and the rotor is many times higher than the density of energy at which an electric field would cause electrical discharges.
Electrostatic motors can be useful (and they are actually used in certain devices) only at microscopic sizes.
Hmm, so I guess you would have to fabricate an array of millions of microscopic electrostatic motors. Which is kind of like what biological muscles are in a way, right?
Constraining the electrons apart would require a very serious insulator. The muscle would just arc between its two ends.
To make it work you have to distribute electrical potential along all the "motor". Just like biological muscles do with protein configurations. We just aren't technogically advanced enough to build such metamaterials ourselves.
If you charge two halves of a muscle oppositely so they attract, you would get arcing between them without a strong insulator in between. But if you charge two halves both negative or both positive there would be no arcing between them. They would still strongly repel and it seems like you could use that to do work.
Electrostatics generally require high voltage (the HASEL muscles you linked to require 2-20kV [0]) to generate usable force.
This creates lots of engineering and regulatory challenges for product development because, as the esteemed William Osman says, "Welcome to the world of high voltage, where everything's a wire and you're probably going to die" [1].
Even if you do not have a motor but just a single charged sphere, at its surface there will be an electric field increasing with the charge.
At a certain charge value, and at a not very large one, the surface electric field will exceed the breakdown field of air and a corona discharge will start.
So unfortunately the idea of using the repulsion forces does not work.
To prevent the discharges, the entire environment around the 2 charged moving parts would have to also be charged with the same sign, but then the repulsion forces between your parts would be balanced by the repulsion forces from the surrounding medium.
High-voltage equipment, e.g. high-voltage transformers, is indeed immersed in insulating fluids, either in special insulating oils or in the gas sulfur hexafluoride, which is more convenient than liquid oil.
This increases several times the breakdown field compared to air but it is not enough to reach similar energy densities like with magnetic fields.
To give some numbers, the air breakdown field is around 3 MV/m, while the maximum magnetic field in a motor might be up to 2 Tesla.
The ratio of the energy densities is the square of the ratio between the product of the magnetic field with the speed of light and the electric field, i.e. the square of (2 x 3 x 10^8) / (3 x 10^6), so 200 squared, i.e. 40 thousands.
Even if you increase the breakdown field 10 times, which is quite hard to achieve with fluids, the magnetic field would give forces much, much higher at a given size.
For a bit, but if you keep raising the voltage you find the electric breakdown happing on the outside surface of the robot (or whatever’s using the electric field muscle) instead of where you put the insulation.
You can't create a monopole, either electrostatic or magnetic. If you impress a negative charge on something, there must be an equally strong positive charge somewhere nearby that you'll have to insulate somehow.
This reminds me of Randall Monroe's "What If" blog/book. I really enjoy these types of questions, which are adequately described by Munroe's subtitle: "Serious scientific answers to absurd hypothetical questions."
What an amazing write up. I feel inspired to study physics now. I wonder how my life might be different if I sought math and science courses instead of bailing after calculus.
> when still it took several clicks to find the name of the author
Well, for 0 clicks the post is noted "by Brian", and for one click the blog's About page identifies him as "Brian Skinner[,] an assistant professor in theoretical condensed matter physics."
> In short, if I lost 1% of my electrons, I would not be a person anymore. I would be a bomb. A Coulomb bomb, if you will, with an energy equivalent to that of ten billion (modern) atomic bombs. Which would surely destroy the planet. All by removing just 1 out of every 100 of my electrons.
The Chicxulub impactor struck with the force of ten billion Hiroshima bombs, and while the world underwent a mass extinction event, the planet itself was fine.
That depends on your quality metric. I don't think the dinosaurs thought it was fine.
IMHO, destroying all of the things that are cool and interesting (to me) about this planet counts as "destroying the planet" even if there is still a hunk of rock orbiting the sun afterwards.
The spherical cow in a vacuum approximation I used in a different thread gave me 1e33 J, which is 4.78e15 Tsar Bomba nukes or 1.6e19 Little Boy nukes.
This was unnecessarily compact (because the suggestion there was drinking antimatter) and thus high-energy, but it’s 4 times the gravitational binding energy of planet Earth.
Planets are tough things. Destroying them is hard, oh the things on them sure. But the whole planet no. It will just probably gather itself together in a while anyway...
I don’t see why we can store energy with this concept. Eg getting even a small object to .01% charge would be a ton of energy.
We could store it with something with an equal and opposite charge (across a large insulator) to cancel out the net pull on things. And encase it in even two meters of glass or plastic if needed.
That’s not what I mean though. Capacitors are limited by the breakdown voltage. But what if we make the plates separate by more distance and just increase the charge.
You can but eventually the voltage gets so high that the resistance of the air isn't enough to prevent a short via a discharge. And in a vacuum, the resistance is even less. One would have to keep the capacitor in a super resistant gas or fluid to prevent a short.
Not even close. My (excessive) estimate in another thread is 1e33 J, which would have a Schwarzschild radius of about 16 picometers, and something (I don’t really understand it) happens if a black hole is charged which makes the event horizon radius smaller than the Schwarzschild radius.
Now I’m wondering what would happen if you tried to create a black hole purely from the energy density of an electric field. Do you asymptotically approach an extremal charged black hole? Or do you make a super-extremal black hole? I’ve heard conflicting claims about if super-extremal is even possible.
If you could somehow do that without the 140 gigacoulombs of charge exploding violently before you got close, approximately this: https://youtu.be/YtCTzbh4mNQ?t=16
If you don’t invoke space magic to prevent the positrons from exploding even before they annihilate anything, and they are confined into a 0.1m radius ball, the charge density energy overwhelms the annihilation energy and the ball of positrons explode with a yield of ~1e33 J, which — without exaggeration — looks more like this: https://youtu.be/KNjWpSglUOY
Yes, assuming all those positrons started out in your stomach, the actual antimatter wouldn’t add significant energy in comparison. The charge balance stays the same when positrons and electrons collide. So, bigger boom than just an anti mater sandwich, not that you would notice the difference.
Relativity actually makes this worse as the electrons are limited to the speed of light but the charge can keep dumping ever more energy into them until their far enough apart.
What would happen to us if we were suddenly able to understand anything with no effort ... no matter what the question, as soon as we thought of it, the answer appeared?
This reminded me of this quote from "Midnight in Chernobyl". Quite amazing to thing of such small amounts of mass being converted into such extraordinary amounts of energy.