Determinism and the cosmic charge

# Determinism and the cosmic charge

TL;DR – Why are the laws of physics deterministic? Because those are the ones we can write.

I remember talking to a friend of mine in university. “Isn’t it fascinating” he commented “that the laws of physics are deterministic? What does it tell us about the universe? What does it tell us about the nature of God?” he went on. “Yes, yes… all very interesting” I replied “but could we talk about it after the exam?”

Deterministic, in this context, simply means that if we give the initial state of the system, we are able to tell its final state. For example, if you leave a bag of potato chips open in the break room, it will be empty by the time you come back 5 minutes later. That’s just basic science.

Quantum mechanics does not change this. The only difference is that the state of the system is an ensemble. An ensemble, in this context, is not a group of people yelling at the drummer because he is rushing. Rather it’s a statistical distribution. And given the initial statistical distribution you are able to tell the final statistical distribution. So quantum mechanics is, in this sense, deterministic.

It is natural, then, that people wonder why the laws of physics are deterministic. Maybe it tells you that the universe is a perfect machine, self-consistent and self-sustaining. Maybe one sees the hand of God in the creation, giving it order and rationality. Maybe another sees the power of the human mind in understanding the universe. Or maybe they just can’t find anything to watch on TV…

But maybe there is another, more mundane, reason. The laws of physics are deterministic because those are the only processes we can study scientifically. That is: when we do science we have deterministic-colored glasses, available in any size. And what better way to show what I mean with a convoluted and nonsensical thought experiment?

## The cosmic charge

Imagine you are a scientist. I know, I know. Just try. Not a famous scientist, just a regular one intent on fixing his detector. Stupid seal does not seem to hold the vacuum properly. Who knows what the students have done with it. Anyway, there you are and in comes a friend of yours who claims to be an engineer. I know, right? And he is also super excited. That does not bode well…
“<Insert your name here>! I have made a tremendous discovery! I have uncovered the mysteries of the cosmic charge!” he shouts, quite loudly, with a big black box in his hands. “See” he shows you all excited “I press this button.” He presses a button and a number appears. “I detect two units of cosmic charge! I press it again,” he presses it again and another number appears, “and now there are… wow! Five units of cosmic charge! That’s a lot of cosmic charge!!!”

“Wow! What a discovery!” you say politely and sarcastically. “So, how do you prepare a unit of cosmic charge?” “Oh, no you can’t prepare it.” He says and after he stares at your puzzled expression for enough time adds, “You see, you can’t manipulate the cosmic charge. It’s so elusive! You can’t create a machine that prepares a set amount of cosmic charge. In fact, there exists no process that, for the same initial state, gives you the same final state of cosmic charge!” he says triumphantly. “That’s why it’s so cool!”

While you try to understand whether your scientific intuition wants to bang its head on the wall or simply throw up, you try to ask candidly, “Good sir, pray tell: if you are not able to prepare a specific amount of cosmic charge, how were you able to calibrate your ingenious detector device?” He stares blankly at you. “How do you know that when the device says two, there are actually two units of charge instead of five?” His stare is the emptiest thing in the universe… emptier than any vacuum you were ever able to prepare… you wish you had something that could hold such good vacuum. “To make sure that my detector is calibrated,” you say in your talking-to-a-five-year-old voice, “I use a known amount of charge, so that I know that detector response corresponds to that amount of charge. How did you calibrate yours? How do I know your device is not just a random number generator?”

“Oh, I wasn’t aware of this ‘calibration’ business,” he says while you wonder whether he actually has a degree in engineering. “No big deal. I’ll go work on it a little more.” And you go back at cursing your detector.

Now a few days later… Yep: he comes back. I’m terribly sorry. “<Insert your name here>! After extensive research I realized I was wrong!” that gives you a glimmer of hope that is soon shattered. “But now I have really uncovered the mysteries of the cosmic charge,” he says triumphantly. “See,” he turns a knob and presses a button, “now I have prepared two units of cosmic charge.” “See,” he turns the knob again and pushes the button again. “Now I have prepared five units of cosmic charge! That’s a lot of cosmic charge!”

“Wow! What a discovery!” you say circumspectly, like a speleologist who realized the cave he stepped into is inhabited by a bear. “So, now you can both prepare and measure cosmic charge?” “Oh, no you can’t measure it,” he says, and after one of the veins on your forehead pops he adds, “You see, nothing can be affected by the cosmic charge. It’s so elusive! You can’t create a machine that tells the amount of cosmic charge. In fact, there exists no process that, given its final state, allows you to reconstruct what was the initial state of the cosmic charge!” he says triumphantly “That’s why it’s so cool!”

Your scientific intuition is now sitting alone in a dark corner, repeating “make it stop! Make it stop!” You ask “Good sir, pray tell: if you are not able to detect a specific amount of cosmic charge, how were you able to calibrate your ingenious preparation device?” The emptiness in his eyes is beyond your comprehension. “How do you know that when you turn the knob to two units there are actually two units being created instead of five?” You instinctively grab hold of a table as to not be sucked into the emptiness. “To make sure that my radiation source is calibrated,” you say in you talking-to-one-year-old voice… the one where you know you are not going to be understood anyway, “I check with my Geiger counter, to make sure it corresponds to the correct amount. How did you check? How do I know your device does anything at all?”

“Oh, I have to calibrate my preparation device as well?” he says while you wish you had a hearing implant you could turn off. “You tell me I have to be able to both prepare known states and detect them? That is very limiting… I never realized that science was so limited… It’s like everything I want to talk about scientifically needs to be empirically well defined. Who would have thought!” and he goes away. Yes, you think to yourself, science would be a lot easier if I didn’t have to worry about all that… But you are satisfied: your vacuum is holding. Now, about those stupid electronics…

## Determinism and reversibility

What is the point of this story? And it’s not just to lock your lab when you are doing complicated work. As we saw, to be able to define the cosmic charge we need to be able to prepare it: we need a procedure that given a set initial state we get to a set charge amount. Schematically: we have a black box with a knob, we set the desired value, press a button and voila! The desired amount of cosmic charge is in front of us.

Now, this may be a very complicated procedure. To prepare a beam of protons at a set energy inside a particle accelerator we first get some hydrogen, strip the electrons, accelerate the protons away from the electrons using a linear accelerator, when they are fast enough they go into a booster ring, where magnets have to bend their trajectory according to their speed, and plenty of people need to stay there monitoring the thing, oh make sure your magnets don’t quench or you may lose helium which explosively expands destroying over 50 magnets and contaminate your vacuum. However complicated the procedure, upper management can always put all of this in a big black box with a knob and a button. Which is about as much as they can understand.

The point is that given the initial state of the knob (its setting) we must be able to tell the final amount of the cosmic charge we have prepared. That is: we must have at our disposal a deterministic process.

Conversely, we also need to be able to detect it: we need a procedure that given the final state of the detector we can reconstruct the initial amount of cosmic charge. Schematically: we have a black box with a button, we press it and voila! The screen tells us the amount of cosmic charge in front of us.

This too may also be a very complicated procedure. To measure the energy of an incoming electron we may make it interact with a material so that it emits high energy photons, which convert into electron-positron pairs, which interact with the material, and emit other high energy photons, and so on, creating a shower of particles, and the photons are collected and absorbed into photomultiplier tubes, which create an electric current, and there are thousands of wires and you have to be sure that they are well connected, or maybe you come to the wrong conclusion… like that neutrinos are going faster than the speed of light or something. But again, upper management can always put us all into a big black box.

The point is that given the final state of the detector display (the value on it) we must be able to tell the initial amount of cosmic charge. That is: we must have at our disposal a reversible process. One that allows us to reconstruct the initial state when given the final state.

If these processes are not available, even conceptually, we can’t do physics. In fact, the discovery of new techniques to reliably prepare and measure states typically means advances in science. It was the design of Otto von Guericke for the first vacuum pump that allowed Boyle and Hook to notice that the product of pressure times volume is constant. I suspect it also allowed them to have problems with sealing their vacuum. It was the invention of the mercury thermometer by Fahrenheit that allowed Gay-Lussac to notice that the pressure is proportional to the temperature. The combined ability to prepare a gas at different pressure and the ability to measure the temperature of a gas precisely is what gave us the law of an ideal gas PV=nRT. I could fill pages with such examples… but I don’t feel like it: you can’t expect me to do everything myself. I’ll just overgeneralize from this one specific example.

It is the availability and identification of such deterministic and reversible processes that allows us to do physics. Therefore it should not be surprising that what we can describe physically obeys deterministic laws. These are the only things we can describe scientifically within this vast, complicated universe; full of galaxies, full of stars but mostly full of empty space. Hhhmmm… Now that I think about it, the universe can really hold its vacuum. I wonder how it does it.

## 2 Replies to “Determinism and the cosmic charge”

1. Jeff Landgraf says:

The argument for the necessity of deterministic laws (or at least something that looks close to deterministic) can be extend far beyond the realm of physics. Without at least a moderately consistent causality it would be impossible to make any sense of the world at all which would preclude consciousness. MOreover specific traits would not consistently bring success, so it is difficult to see how any living creatures could develop.

Also, the ensemble interpretation of qm may restore determinism to the theory, but it does not restore determinism to the universe. Take a Chunk of U238 and qm does not have any prediction for the time of the next decay, but the next specific decay will occur at some specific (if unknown) time…

(Sorry about the caps, the web page won’t allow lower case!)

1. Gabriele Carcassi says:

Hi Jeff!

Yeah, I don’t know what’s the deal with all caps here… But the comment came out fine in the end.

I agree that the argument extends… It would be very confusing if cat meant cabbage or plier every now and then. We couldn’t form memories if every time we accessed them they changed (though I understand that happens to some degree). Without some kind of causal nothing can essentially exist in any meaningful way.