Logical positivism [split: A splendid video about evolution]

I think it’s you who are misinterpreting what physics actually tells us. The mathematics behind the block universe is sound: solutions to Einstein’s field equations yield metrics in which time t is a coordinate on the same footing as x, y, z.

This is only true because physicists redefine space and time by introducing a metric which is not an identity matrix.

That befuddles many who don't know physics, and almost certainly confuses the hell out of some physicists.

My point is that it really isn't playing ball to redefine ideas that already have a meaning!

The idea of a block universe seems much less exciting when you realise that the time dimension is multiplied by sqrt(-1).

This leaves non scientists to either 'admit' that they never understood what space and time were (!!) or to just give up. On the other hand, kids learning science go away with the idea that non-scientists don't understand what space and time are.

David

This is only true because physicists redefine space and time by introducing a metric which is not an identity matrix.

That befuddles many who don't know physics, and almost certainly confuses the hell out of some physicists.

My point is that it really isn't playing ball to redefine ideas that already have a meaning!

The idea of a block universe seems much less exciting when you realise that the time dimension is multiplied by sqrt(-1).

This leaves non scientists to either 'admit' that they never understood what space and time were (!!) or to just give up. On the other hand, kids learning science go away with the idea that non-scientists don't understand what space and time are.

David

There’s nothing odd about sqrt(-1) - what would the issue be in your opinion?

There’s nothing odd about sqrt(-1) - what would the issue be in your opinion?

Well suppose you tried to rent an office for a certain chunk of time, and you specified this in terms of a 4-volume. Since you couldn't expect the clerk to know about metrics, you would specify the 4-volume as 4 metres x 4 metres x 4 metres x sqrt(-1) x q, where q could be whatever you thought appropriate.

Tell me what response you would be likely to get!

Or maybe tell me how you visualise a 4-volume.

Yet people end up talking about the block universe because physicists have fed them that concept (often without the sqrt(-1)).

David

Well suppose you tried to rent an office for a certain chunk of time, and you specified this in terms of a 4-volume. Since you couldn't expect the clerk to know about metrics, you would specify the 4-volume as 4 metres x 4 metres x 4 metres x sqrt(-1) x q, where q could be whatever you thought appropriate.

Tell me what response you would be likely to get!

Or maybe tell me how you visualise a 4-volume.

Yet people end up talking about the block universe because physicists have fed them that concept (often without the sqrt(-1)).

David

I don’t follow your argument but I accept that complex numbers are needed in some mathematical models of the world. They are all over in quantum mechanics so why not in gravity?

If your point is that physicts should be less outspoken in metaphysical debates about how much exactly we can claim to “know” I agree. As Newton wrote “What we know is a drop. What we don't know is an ocean,”