Page 359 - Mike Murphy's Blog Posts

Spacetime was ‘devised’ by Albert Einstein to describe the universe around us. He surmised that we live in a three spatially dimensional universe, with a time dimension, moving only forwards. (Although, interestingly , there is nothing in physics which prevent moving backwards in time, except, perhaps entropy...)
So, according to Einstein, everything in our universe exists in a four-dimensional spacetime. We cannot move through space without also moving through time.
And vice versa!! This is the critical point here, we cannot move through time without also moving through space. If you wanted to go back in time, let’s say by 100 years, then you must also move through the relevant space too, to reach that particular point in spacetime.
Even if you only wanted to go back five minutes in time, you’d need to move through space to the relevant place.
So, if you were to build a time machine, it would have to be able to move you through both space and time, to the point you’re trying to reach. Which is tricky, to say the least.
Also, can you be sure that the point you’re aiming for is actually “there”? This raises a very serious issue. All time travel notions have one basic assumption - that your ‘destination’ exists! Somewhere. And sometime!!
I find this quite disturbing since it means that ALL of spacetime must exist, for ALL time. As a physicist I consider this to be too bizarre. Why should all of spacetime, for all space and all time, exist, for all of time?
It’s simply ludicrous. I can’t accept that idea.
So that’s the ‘NO’ argument. What is the ‘YES’ argument?
That’s simple. We are all time travellers. Each day we travel through time, and space, at the rate of one second per second, one hour per hour and one day per day.
Forwards, never back.
Mike’s Blog Posts 359