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As COP28, the 2023 United Nations Climate Change Conference, kicks off we look at how maths can help understand the climate crisis.

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- We talk about a play that explores the fascinating mathematical collaboration between the mathematicians GH Hardy and Srinivasa Ramanujan.

- I have a few thought about your reflexions about Time:

What if ‘time’ does not exist:

What we call speed or velocity is not the rate of change of distance with respect to time, but simply the change of position with respect to Space.

Objects do not move over time (because time does not exist). Objects simply move in Space. This started with the big bang.

What we perceive as time is a product of our minds which have the capacity to :

-retain mental images of positions of objects that we have observed.

-extrapolate the positions of objects if they continue on their existing paths

The concept of 'time' is thus purely an abstract idea that we humans have introduced to explain the fact that we observe positions of objects changing.

The fact that objects move and interact with each other is surely sufficient to explain all the phenomenon we observe in the universe without need for the concept of time.

At the Big Bang, objects and energy start moving in Space, and that movement resulted in all states of the universe that have been observed. There is no need for ‘time’ to explain this, just the laws of nature together with motion through space.

This would mean that time travel does not exist (because time does not exist).

However, we could re-visit any former state of the universe simply by putting all the objects in the universe (down to the molecules, and sub-atomic particles in our brains) back in the positions they held in space (with the same momentum, energy etc.. that they had when they were in those positions).

And, to create any ‘future’ state of the universe we simply need to move all objects in it to the place that we extrapolate them to be in at a later state of their motion through space.

The only barrier to this kind of ‘time travel’ is that in practice it would be difficult to move all that stuff (everything in the universe) to its previous or expected position.

Thus, time does not exist – If I want to go back to a 'time' when my Mother was alive, for example, all I need to do is move particles to the correct positions in space corresponding to that state of the universe.

If I simply did that, she and I would inevitably be having the same thoughts, and memories as we had the first time. And we would effectively have travelled back in what we call ‘time’ but which is, in fact, just a previous position of objects and energy in space.

Maybe it would simplify the equations of cosmology and quantum mechanics if we re-visited them from the perspective described above.

- I would be very interested to know what you think about the ideas I have expressed above.