3
votes
3answers
543 views

Time travel and nuclear decay

Reading a previous closed question an interesting variation has come to my mind. Suppose that time travel to the past was possible: I wait for an atom to decay and measure the time, $t_{1a}$ I ...
17
votes
6answers
937 views

Is there a difference between observing a particle and hitting it with another particle?

First, let me state that I'm a lot less experienced with physics than most people here. Quantum mechanics was as far as I got and that was about 9 years ago, with no use in the meantime. A lot of ...
18
votes
10answers
1k views

Why can't the outcome of a QM measurement be calculated a-priori?

Quantum Mechanics is very successful in determining the overall statistical distribution of many measurements of the same process. On the other hand, it is completely clueless in determining the ...
26
votes
10answers
1k views

What is the difference between a measurement and any other interaction in quantum mechanics?

We've learned that the wave function of a particle collapses when we measure a particle's location. If it is found, it becomes more probable to find it a again in the same area, and if not the ...