Time travel (hijack from Reality Paradox)

[Time Traveler]

Imagine that we attach a label to each elementary particle in the Universe, each label having a unique natural number ... In this model, everything who can be send in past  is represented a series of labels. If a thing is sent back in time...a phone for exemple (we assume that it contains the elementary particles with the numbers 7 and 1003) then we will find in the past, simultaneously these elementary particles twice, in the same Universe and at the same time. Do you think it is possible?

[joigus]

7 minutes ago, Time Traveler said:

Imagine that we attach a label to each elementary particle in the Universe, each label having a unique natural number ... In this model, everything who can be send in past  is represented a series of labels. If a thing is sent back in time...a phone for exemple (we assume that it contains the elementary particles with the numbers 7 and 1003) then we will find in the past, simultaneously these elementary particles twice, in the same Universe and at the same time. Do you think it is possible?

One of the principles of quantum mechanics is that elementary particles have no labels. All electrons are the same electron in a sense that's very clear in the mathematics of QM. So no, we know it's not possible.

[Time Traveler]

15 minutes ago, joigus said:

One of the principles of quantum mechanics is that elementary particles have no labels. All electrons are the same electron in a sense that's very clear in the mathematics of QM. So no, we know it's not possible.

I thought of the elementary particles as the pieces of the LEGO game (https://en.wikipedia.org/wiki/Lego)
I associate a label with each seemingly identical piece

Can we sent  a fossil for 1 to 10000   years in the past?

Quote

A fossil (from Classical Latin: fossilis, literally "obtained by digging")^[1] is any preserved remains, impression, or trace of any once-living thing from a past geological age....Specimens are usually considered to be fossils if they are over 10,000 years old

 

[joigus]

25 minutes ago, Time Traveler said:

I thought of the elementary particles as the pieces of the LEGO game (https://en.wikipedia.org/wiki/Lego)
I associate a label with each seemingly identical piece

It's a natural thought and physicists did think in those terms in the past. But when the rules of quantum mechanics started to become clear, it was realised that the only states that make sense for quantum particles are some special average over all the identity tags.

So ultimately there is no really meaningful sense in which you can say 'this electron' or 'that electron'.

[swansont]

2 hours ago, Time Traveler said:

I thought of the elementary particles as the pieces of the LEGO game (https://en.wikipedia.org/wiki/Lego)
I associate a label with each seemingly identical piece

Then they aren’t identical. But particles of the same type are.

2 hours ago, Time Traveler said:

Can we sent  a fossil for 1 to 10000   years in the past?

 

No.