Exploring the Mysteries of Discrete Spacetime at Quantum and GR Scales

In summary, the first question asks about what holds spacetime together at a larger scale if it is discrete at the quantum level. The second question raises philosophical implications of a discrete spacetime and its relationship to renormalization. Different theories approach this issue from a classical or quantum perspective. The possibility of objects moving through discrete spacetime is also discussed, and the concept of transition probability is introduced. The concept of the Heisenberg uncertainty principle is also mentioned.
  • #1
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If spacetime is discrete at the Quantum/Sub-quantum scale, what "joins" and keeps spacetime together at GR scales?

P.S. What "Separates" spacetime at Quantum scales?
 
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  • #2
The first question is easy. A coarse grained surface looks smooth from a distance.

The second question is more philosophical. In a discrete space-time it is assumed that distances and times come in fixed irreducible chunks.

One attraction of a discrete space time flows from how renormalization is done. Without renormalization, QM equations "blow up" into infinitities, while renormalization sets an arbitrary and consistent cutoff to prevent that from happening and this provides real answers. A discrete space time elevates renormalization from being a mere mathematical trick to an actual feature of space time, and since there is a naturally plausible set of discrete spaces and times (the Planck scale) it is plausible to look to that as the cutoff.

Discrete space-time theories like causal set theory, CDT and LQG all approach quantum gravity from the point of view of time space following GR which views gravity as a time-space curvature issue, rather than from the QM approach of creating a graviton.
 
  • #3
Since spacetime is discrete at the Quantum/Sub-quantum scale, is it possible that something that occupied a discrete spacetime move to the other discrete through straight line?
 
  • #4
the definition of straight line does not make sense when alluding to sites which are just neighbors, since the space between two adjacent sites don't have, in principle, a physical status.

Best Regards

DaTario
 
  • #5
I agree with your opinion. So how do they travel? Do a matter, in Quantum/Subquantum scale, actually travel through higher dimension?
 
  • #6
I would suggest something which is typical in the quantum formalism. I would suppose the existence of some system of coordinates in which, using this smallest scale, the triples would be always integer numbers. Then I would suggest that movement is in fact the consequence of existing a matrix of transition probability. Transitions from one triple to the other. Due the correspondence principle, adjacent site transitions generally are given higher probabilities when coming to macroscopic objects.
 
  • #7
DaTario said:
I would suggest something which is typical in the quantum formalism. I would suppose the existence of some system of coordinates in which, using this smallest scale, the triples would be always integer numbers. Then I would suggest that movement is in fact the consequence of existing a matrix of transition probability. Transitions from one triple to the other. Due the correspondence principle, adjacent site transitions generally are given higher probabilities when coming to macroscopic objects.

Logically a Macro entity by virtue of size, will always have this as a limit to "hitting-quantum-targets", for instance if you have two marble's, one the size of Earth and one 'normal' size, then the Earth size will have a problem colliding with a small 'normal' size marble. Conversely, a normal size marble will have no problem at all in being directed to a marble the size of Earth.

Quantum entities have no HUP factors when being directed at Macro Targets, they are sure-fire probable certainties in hitting their targets.

HUP has a 'two-size' dependant principle factoring
 

What is discrete spacetime?

Discrete spacetime is a theory that suggests that spacetime is not continuous, but instead made up of individual units or "bits" of space and time. This theory is currently being explored in the field of quantum mechanics and general relativity.

What are the implications of discrete spacetime?

The implications of discrete spacetime are far-reaching and have the potential to revolutionize our understanding of the universe. It could help resolve issues such as the unification of quantum mechanics and general relativity, the nature of black holes, and the origin of the universe.

How is discrete spacetime being studied?

Scientists are using various mathematical models and experimental techniques to study discrete spacetime. Some methods include quantum field theory, loop quantum gravity, and experimental tests such as measuring the speed of light and gravitational waves.

What is the connection between discrete spacetime and quantum mechanics?

Quantum mechanics describes the behavior of particles on the smallest scales, and the theory of discrete spacetime suggests that space and time are also quantized at these scales. This connection could help bridge the gap between the two theories and lead to a more complete understanding of the universe.

What are some current challenges in exploring discrete spacetime?

One of the biggest challenges in studying discrete spacetime is the lack of experimental evidence. It is a relatively new theory and requires advanced technology and techniques to test. There are also ongoing debates and disagreements among scientists about the best approach to studying this concept.

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