Time doesn't actually exist - discuss

I've been doing a horticulture course, learning about energy in plants and growth. Then saw a Brian Cox programme where he said time could in fact not exist at all. In fact, everything we experience could just be energy and reactions. Which meant if you were able to reverse all those reactions you could effectively travel back in "time".

Has anyone else heard this theory?

It's a bit of a simplistic statement to say that 'if all the reactions could be reversed' we could travel back in time.

Time is an arbitrary observation between events made by an independent observer and those events are a function of the physical laws governing the universe.

The French mathematician Pierre-Simon Laplace in the early 19th century, declared (causal determinism) that if one could measure the positions and motion of all the atoms and know all the forces acting in the universe, then one could predict the future through intellect alone.

Heisenberg with his uncertainty theorem and quantum mechanics proved him incorrect 150 years later.

Professor Cox has just implied the same as Laplace's assertion in reverse, moreover all the physical laws of the universe would need to somehow also comply.

And as Scottie loves to say: 'ye cannae change the laws of physics captain'.

That would mean a decrease in the entropy of the universe, so no. Also, it would violate relativity, as what appear to be simultaneous events to one observer may not appear simultaneous to another.

Of course it exist - you're over complicating it. If we can measure it why can't it exist?

Heisenberg with his uncertainty theorem and quantum mechanics proved him incorrect 150 years later.

Has anyone else heard this theory?

Not necessarily. As far as I understand it, there's no reason to think quantum randomness does not operate according to laws that are at present (and potentially by nature) inscrutable. Laplace's conjecture hinges on the premise that we understand all laws, including the ones governing quantum random events.

What do you mean by entropy of the universe Blazar?

I guess that fits in with quantum indeterminacy in which outcomes are described by a probability distribution uniquely determined by the state of the system.

In which case, as you suggest, the complete laws governing that state may not yet be understood.

But then that's how science works; theory is accepted as proof until an observation invalidates the theory.

You have quoted a scientist positing a scientific hypothesis. By definition, it is not a theory. I just wanted to get the terminology correct if you want a scientific debate (though I note that you have posted in a philosophy forum, so maybe science has nothing to do with it, in which case neither has a quote of Brian Cox in a scientific context).

I mean just that. The entropy of the universe. The physical quantity of entropy in joules per kilogram per mole.

Does time actually exist though? Or have we just invented something to measure billions and billions of reactions? I'm not trying to change anything - I'm not on a crusade to burn all of our clocks, I just think it's fun to think that there is no past or future. Only a now and in this now there are just loads of reactions happening.

That would mean a decrease in the entropy of the universe, so no. Also, it would violate relativity, as what appear to be simultaneous events to one observer may not appear simultaneous to another.

How do you know anything exists and you are not just imagining it.

Good point, I just edited the OP to make this clearer.



I don't understand what entropy of the universe is as I haven't ever read anything on that topic - is there a plain English explanation anywhere?