[Serious] Is the Past Real?

[HappySkeptic]

So, suppose that I pick a single uranium atom. ALL we have is probabilities for when it will decay. We do NOT have, even in principle, a way to determine when it will decay. So the statement that it will decay tomorrow at noon is neither true nor false.

But I can go further. Suppose I have isolated a uranium atom last week. I have neither looked at it nor had any detector consider it. Is the statement that it decayed two days ago at noon one that has a truth value?

I would say not, just as the statement that it will decay tomorrow at noon does not.

You are correct, although what determines "measurement" is a nebulous thing.  If a decay emits a Beta particle, it subsequently releases a gamma photon.  There is the possibility of the various particles interacting with other things.

Any of those interactions tend to increase the probability that the decay has been "detected".  Since wavefunction collapse is not actually explained by quantum-mechanics, there is a problem with determining when detection occurs.

One thing is clear - a person doesn't have to do the detecting.  Information just needs to be replicated sufficiently within a system such that the probability that the information doesn't persist for all time becomes vanishingly small.