Donald Trump Treat’s COVID-19 Like Schrödinger’s Cat

There’s not just a slip of the tongue or a misstatement. Donald Trump has made quite often made the claim that the COVID numbers in the USA are so bad because of out testing. Here is an exact quote from June 15 (2020).

“If you don’t test, you don’t have any cases…If we stopped testing right now, we’d have very few cases if any.”

OK, this is just plain silly — as everyone (well, just about everyone knows). Just because you don’t test doesn’t mean you have no cases, it just means you don’t KNOW about those cases.

If you use Trump’s line of reasoning, you could say stuff like this:

  • If you don’t check your bank account, you will never run out of money.
  • If you don’t test for diabetes, you will have very few cases of diabetes (OK, this is cheating since this is EXACTLY what he’s saying).
  • If you don’t use a radar gun to check for speeding cars on the highway, no one will be speeding.

You get the idea, right?

But wait! There is indeed a case where “testing” makes a difference. Maybe Donald Trump is talking about something like the famous Schrödinger’s Cat thought experiment.

This experiment is really a reflection of the quantum nature of reality. But in order to understand this Schrödinger’s cat thing — you need to first look at classical physics.

Suppose I shoot a ball from launcher. If I know the starting position and the starting velocity, then I can find out the position of that ball at any time in the future. Yes, this seems crazy, but it’s theoretically true. If you know the EXACT starting velocity and position, you are all set. You can even take into account the interactions with the air and walls and stuff. That’s classical physics.

Photo: Rhett Allain

But classical physics isn’t the TRUTH. It’s just a model of the real world. It doesn’t work in every situation — in particular, when things get really small stuff starts to get weird. If you want to look at an electron in a hydrogen atom, you don’t get an equation for the trajectory of motion. Instead you get a wave-function.

What the heck is a wave-function? It’s complicated, but basically it’s the solution to the Schrödinger equation. It looks like this.

Yes, there are many different forms to represent this equation but this one just looks cool. Really, the only thing you need to know about is the Ψ — that is the wave function. This wave function can tell you something about the probability of where you can find the electron.

When you get down to really small things, probability is all you get. I know that’s crazy, but that’s what we have. But it’s not probability forever. If you were able to “observe “ (with some type of instrument) the electron in a hydrogen atom, it would be somewhere. So, how do you go from a probability to an actual location?

This is a key idea to quantum mechanics. We say that when a system is observed, the wave-function collapses to a single location. When you observe an electron, you know where it is so that there can’t be a probability distribution anymore.

OK, I think you are ready for the Schrödinger’s cat experiment. It goes like this.

There is this cat in a box. Also in this box is a container of poison. I don’t know why the cat is in with the poison — you can write the back story for homework. But there is a 50 percent chance that the poison container opens up and kills the cat. This means that when you open the box to check on the cat, it’s either alive (with no poison) or dead.

But what about the time BEFORE you open the box? Is the cat alive or dead? If you want to use this as an example of a wave-function, then BOTH outcomes can be true. That means the cat can be a combination of alive and dead. However, when you open the box and observe the cat, its wave-function collapses and it’s really alive or really dead.

Illustration: Rhett Allain (yup, I made this — for you)

So there you go, Schrödinger’s cat experiment. Yes, quantum mechanics is weird.

OK, back to Donald Trump. Is it possible that the corona virus is like the cat in the box? If you don’t measure it, it’s both a positive test AND a negative test? I mean, I guess you could say that — but if you don’t do an actual COVID test, you still observe a person. That person can still get sick and infect others even if you don’t test him or her.

But really, we all know this. Everyone knows it. Honestly, I think Trump even knows it. I suspect this whole “no testing, no cases” thing went like this.

  • Trump is a reality TV president that is very concerned with ratings and numbers. High numbers of positive COVID tests make him (he thinks) look bad. So, clearly more testing means bad.
  • In one of his rambling speeches, he says the “no testing means no cases” thing without really giving it much thought (surprise, right)?
  • Later, someone on his staff points out the problem with his logic. Maybe he gets it, maybe he doesn’t — but it’s a pretty easy idea to understand.
  • Oh well, that doesn’t matter. He said it once so he either has to double down on this statement or say he was wrong. Which one do you think he picks?

So, here we are. He won’t change his statement because he doesn’t want to be wrong. It’s just what he does. Donald Trump’s has been observed and his wave-function has collapsed. We know exactly where he is.

Physics faculty, science blogger of all things geek. Technical Consultant for CBS MacGyver and MythBusters. Former WIRED blogger.

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