# Thread: Points in space and time

1. Does the space in the expanding universe suggest that there is a point within that is fixed, which is maybe the centre, and to which all other points are relative to? Not all things can be relative, otherwise there would be nothing to be relative to. Can the same be true of time? If time is a variable, and ticks by at a different rate depending upon where you are and what speed you are travelling, is there a point/moment where time stands still, and could this even be the same moment in time as the point is in space?
What do you define as a point in space or a moment in time? I guess the Planck lengths could answer this, but how do you combine the two?
Could there be a super dimension which links all points in space and time? If so then I imagine that there is no need to think that the universe has a boundary.

2.

3. Does the space in the expanding universe suggest that there is a point within that is fixed, which is maybe the centre,

It doesn't suggest that. The analogy is often given of the surface of a balloon that is being inflated. The surface expands but there is no point on it that needs to be seen as fixed.

Not all things can be relative, otherwise there would be nothing to be relative to

Not sure I understand this. Why can't all motion be relative? If we consider two objects, A and B, A can be moving relative to B and B can be moving relative to A. There is no need for some fixed point relative to which both are in motion.

4. Originally Posted by ox
Does the space in the expanding universe suggest that there is a point within that is fixed, which is maybe the centre, and to which all other points are relative to? Not all things can be relative, otherwise there would be nothing to be relative to. Can the same be true of time? If time is a variable, and ticks by at a different rate depending upon where you are and what speed you are travelling, is there a point/moment where time stands still, and could this even be the same moment in time as the point is in space?
What do you define as a point in space or a moment in time? I guess the Planck lengths could answer this, but how do you combine the two?
Could there be a super dimension which links all points in space and time? If so then I imagine that there is no need to think that the universe has a boundary.
Fixed relative to what ?

There is no meaning to your question. It would only have meaning if spacetime were viewed as an embedded manifold, but that is not the case.

5. Thanks for the information!

6. Originally Posted by ox
Does the space in the expanding universe suggest that there is a point within that is fixed, which is maybe the centre, and to which all other points are relative to? Not all things can be relative, otherwise there would be nothing to be relative to. Can the same be true of time? If time is a variable, and ticks by at a different rate depending upon where you are and what speed you are travelling, is there a point/moment where time stands still, and could this even be the same moment in time as the point is in space?
What do you define as a point in space or a moment in time? I guess the Planck lengths could answer this, but how do you combine the two?
Could there be a super dimension which links all points in space and time? If so then I imagine that there is no need to think that the universe has a boundary.
When u said: If time is a variable, and ticks by at a different rate depending upon where you are and what speed you are travelling, is there a point/moment where time stands still?

well i can only think of one thing that could stop time, a singularity (black hole), time stands still in them.

7. Originally Posted by ASTROPHYSICIST137
Originally Posted by ox
Does the space in the expanding universe suggest that there is a point within that is fixed, which is maybe the centre, and to which all other points are relative to? Not all things can be relative, otherwise there would be nothing to be relative to. Can the same be true of time? If time is a variable, and ticks by at a different rate depending upon where you are and what speed you are travelling, is there a point/moment where time stands still, and could this even be the same moment in time as the point is in space?
What do you define as a point in space or a moment in time? I guess the Planck lengths could answer this, but how do you combine the two?
Could there be a super dimension which links all points in space and time? If so then I imagine that there is no need to think that the universe has a boundary.
When u said: If time is a variable, and ticks by at a different rate depending upon where you are and what speed you are travelling, is there a point/moment where time stands still?

well i can only think of one thing that could stop time, a singularity (black hole), time stands still in them.
the equation for time dilation breaks down and tends t o0 as the velocity goes to c. While you can never reach c, as you approach it relative to something else, time for you will approach 0 relative to where ever you are comparable to.

8. Originally Posted by ASTROPHYSICIST137
well i can only think of one thing that could stop time, a singularity (black hole), time stands still in them.
So is everything relative to a black hole? My original post was connected to a statement that Bertrand Russell made in his book ABC of Relativity when he said something like - "A superior kind of man is fond of saying 'everything is relative', but if that were true there would be nothing to be relative to". When Russell wrote this I assume that black holes were unknown. Logically then the black hole at the centre of our galaxy must itself be relative to a singularity at the centre of the universe.

9. ...

10. "A superior kind of man is fond of saying 'everything is relative', but if that were true there would be nothing to be relative to".
that is not saying that there must be something fixed or a fixed point.

11. Originally Posted by ox
Logically then the black hole at the centre of our galaxy must itself be relative to a singularity at the centre of the universe.

12. Originally Posted by Ophiolite
Originally Posted by ox
Logically then the black hole at the centre of our galaxy must itself be relative to a singularity at the centre of the universe.
Well obviously I can't defend it, except to say that the only bit of mathematics we have in our brain is logic. From that Russell deduced that 1 + 1 = 2 in the Principia Mathematica. You can only look upon the universe as mathematics and not as mechanics, and somehow the former exists inside our head otherwise we would know next to nothing. My assumption is that within our galaxy everything is relative to the black hole at its centre which in turn is relative to a singularity at the centre of the universe. This leads to a bigger question: why can our brains understand the universe at all?

13. Originally Posted by ox
Originally Posted by Ophiolite
Originally Posted by ox
Logically then the black hole at the centre of our galaxy must itself be relative to a singularity at the centre of the universe.
Well obviously I can't defend it..
Then if you cannot defend it why would you even make such a statement on a science forum? On a bus, possibly? In a bar, probably? While undergoing a psychiatric examination, certainly? But in a science forum?
Originally Posted by ox
.... except to say that the only bit of mathematics we have in our brain is logic...
It may be present in some brains. There is evidence it is not present in all brains. (See next item.)

Originally Posted by ox
... My assumption is that within our galaxy everything is relative to the black hole at its centre which in turn is relative to a singularity at the centre of the universe.
There is no evidence for a centre of the universe.
There is no evidence for a singularity at such a non-existent centre.
There is no scientific justification for your assumption.

Moreover, you do not seem to understand the use of the phrase 'relative to'. Certainly we can consider everything in the galaxy relative to the proposed black hole at it's centre. We can also consider everything in the galaxy relative to the the Number 64 from New Addington to Thornton Heath Pond. You seem to imbue the object to which things are measured 'relative to' with singular importance. The whole point about relativity is that their are no preferred observational points or frames.

14. Fysics is fysics, whether it is at a university, in a bus, a bar or undergoing a psychiatric examinaton should make no difference.

15. Originally Posted by Ghrasp
Fysics is fysics, whether it is at a university, in a bus, a bar or undergoing a psychiatric examinaton should make no difference.
No. Physics is phucking physics, not fysics. And logic is logic and it is noticeably absent from most of ox's posts.

16. But the principles of Physics can be assumed to be the same in a bar, for someone examined by a psychiater or for a psychiater. Because "the laws of fysics are supposed to be the same for all observers". You obviously didn,t get my fine sense of humor..
What does Phuck mean by the way ? :?

17. What does Phuck mean by the way ?
it is a form of length dilation where the relative position of the end, if measured and plotted, forms a cyclic waveform function over time.

18. hmmm

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