Q&A: Schrödinger’s Cat and Time
Schrödinger’s Cat and Time
Question
Hi Michi, I have two questions.
1) In Schrödinger’s cat, only when we open the box do we know whether the cat is alive or dead. Why does our measurement change anything? And if it were a transparent box, would we see the cat half alive and half dead?
2) In The Science of Freedom you say that you accept Bergson’s conception of time rather than Einstein’s. Why? Isn’t Einstein’s conception what physics says?
Answer
1. Whoever knows how to answer that will probably get a Nobel Prize.
2. No. The dispute is in the philosophical interpretation, not in the physics.
Discussion on Answer
1. I think you can’t. When you see it, that itself is a measurement. It’s only a thought experiment. But experiments have been done on particles, not on cats.
2. I touched on this in my article on Zeno’s arrow. You can search for it here on the site.
Regarding 1, if measurement really changes things, then maybe that undermines the Copenhagen interpretation?
I never understood the Schrödinger’s cat experiment. In my opinion, the device that senses whether the radioactive atom decayed also functions as an observer, and therefore it will either sense the atom’s decay or it won’t. What does the Rabbi think?
In the thought experiment there is no such device.
What do you mean? In the experiment there is a device that’s supposed to break the poison ampoule, isn’t there?
That’s not a measuring device, and you don’t necessarily know when or whether it happened.
A device that senses the atom’s decay isn’t a measuring device? After all, the “measurement” being discussed is simply checking whether the atom decayed.
There is no device that measures the decay. When you open the box, you see that the atom decayed at some point.
You simply wait for two half-lives and then open the box.
From Wikipedia: “In the box there is a radiation detector connected to an electrical poison capsule, and if the atom decays, the detector activates the capsule, which kills the cat.” That is, the detector is supposed to sense the decay.
As far as I know, it isn’t a detector but rather a mechanism triggered by the decay. This brings us back to the question of what exactly a detector is and what a measuring device is, and as far as I know there is no clear answer to that.
I think it’s a Geiger counter. At least that’s what it says in the English Wikipedia. It seems to me that this should count as a measuring device, and if so, then once again there is no paradox.
Regarding 1, could one in principle carry out Schrödinger’s cat experiment and then know whether it really was half alive and half dead?
And regarding 2, what should one read / study in order to know about the subject, and has the Rabbi written about it?