What Is the Relationship Between Time and Space in the Universe?

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SUMMARY

The discussion centers on the philosophical and scientific relationship between time and space within the universe. Participants reference the ideas of Gottfried Leibniz and Immanuel Kant, emphasizing that time is a construct of human perception while space exists independently of human thought. The conversation also touches on Einstein's General Relativity (GR) and the concept of spacetime as a physical entity, with participants debating whether spacetime is merely a tool for description or an integral part of the universe. Key points include the interdependence of space and time, the role of mathematical frameworks in physics, and the implications of quantum gravity theories.

PREREQUISITES
  • Understanding of General Relativity (GR) and its implications on spacetime.
  • Familiarity with philosophical concepts from Leibniz and Kant regarding time and space.
  • Basic knowledge of quantum field theory (QFT) and its relationship with GR.
  • Awareness of the mathematical frameworks used in physics, particularly in describing spacetime.
NEXT STEPS
  • Explore the mathematical foundations of General Relativity and its predictions.
  • Study the philosophical implications of spacetime as discussed by Leibniz and Kant.
  • Investigate quantum gravity theories, particularly Loop Quantum Gravity (LQG).
  • Learn about the role of measurement and observation in quantum mechanics and its impact on our understanding of reality.
USEFUL FOR

Philosophers, physicists, and students of science interested in the foundational concepts of time and space, as well as anyone exploring the intersection of physics and philosophy.

  • #31
chill_factor said:
You can seriously see the wavefunction - the absolute square of it.
Sorry to say that, but that's a huge conceptual difference.

chill_factor said:
Lets take the graviton instead. To distinguish a graviton signal from a neutrino signal would require shielding that would collapse into a black hole. Therefore the graviton is not observable in principle. http://arxiv.org/abs/gr-qc/0601043
I am sorry but as long as there is no reliable theory of quantum gravity which explains what the "mathematical entity graviton" means we cannot safely say whether a "graviton as physical entity" does exist. In addition it may very well be that the final theory of quantum gravity does not even contain a graviton as fundamental d.o.f., therefore it could be that it does neither exist mathematically nor physically and that there is no such problem at all.

chill_factor said:
How many things are simply not observable because their detection or creation has unphysical requirements or even physically impossible requirements?
A lot - but why should we care? OK, you may complain about the fact that a specific theory (which one?) contains too many unphysical entities and that (according to Ockhams razor) it should be replaced by something which is less wasteful ontologically. Of course you are invited to develop such a theory (what do you have in mind?).
 
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  • #32
chill_factor - What about a photon moving at c, it's not observable between events. What do you make of this stuff that separates events?
 
  • #33
chill_factor said:
I believe it does. I'd say science is not a subset of philosophy that deals with empirical things; it is a subset of engineering that deals with fundamental limits instead of practical limits.

I think you should review what engineering and science are. Here are a couple of links.
http://en.wikipedia.org/wiki/Engineering
http://en.wikipedia.org/wiki/Science

As such, the physicality (observability) of the systems we deal with is important. At the end of the day science is not philosophy because science is about data.

Here's a link to philosophy. And on the philosophy of science.
http://en.wikipedia.org/wiki/Philosophy
http://en.wikipedia.org/wiki/Philosophy_of_science


Just read some arXiv high energy, cosmology, etc. papers and tell me with a straight face that if those disappeared tomorrow, the world would be a worse place.

It would be, for we would not know what paths have already been taken.
 

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