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Nano-Passion
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Or do we have no idea?
...This [HOLOGRAPHIC PRINCIPLE] also seems to be saying the finite area of a black hole [horiozn] can hold only a finite amount of information. This suggests a discrete nature of space and time. [1 bit per Planck area.] The idea that there is an absolute limit to information on the other side of a horizon is known as Bekenstein’s bound. There is no way to reconcile this with the view that space is continuous.
On the Planck scale space seems to be composed of fundamental discrete units. String bits are one view of this, the Bekenstein bound from black hole thermodynamics is another. (LQG sees these discrete units as spin networks.) It’s possible these are three different approaches to the quantum world..maybe there is a way of unifying them...
Naty1 said:I came across these notes of mine which might be of interest.
from Lee Smolin, THREE ROADS TO QUANTUM GRAVITY:
Naty1 said:We have no idea.
Nobody knows exactly what space or spacetime actually is...
try this discussion:
https://www.physicsforums.com/showthread.php?t=323557&highlight=is+spacetime+real
A search will turn up hundreds of discussions closely related to this subject.
My own suspicion is that it is likely discrete because at Planck length and smaller, about 10-33 cm quantum foam seems to destroy conventional ideas of space,time,matter,etc.
But the continuous perspective works very well in most of classical physics...like relativity.
Naty1 said:We have no idea.
Nobody knows exactly what space or spacetime actually is...
try this discussion:
https://www.physicsforums.com/showthread.php?t=323557&highlight=is+spacetime+real
A search will turn up hundreds of discussions closely related to this subject.
My own suspicion is that it is likely discrete because at Planck length and smaller, about 10-33 cm quantum foam seems to destroy conventional ideas of space,time,matter,etc.
But the continuous perspective works very well in most of classical physics...like relativity.
bcrowell said:A little over a year ago I asked for comments on Smolin's arguments as presented in that book, and got some very helpful responses: https://www.physicsforums.com/showthread.php?t=391989
Naty1 said:
Naty1 said:Quantum foam is the quantum fluctuations which seem inevitable at small scales...say about Planck size...it ruins the ability to make measurements of space,time,mass,etc...they all become blurred. A crude analogy: smooth rolling waves in the sea become frothy when strong winds are present, tops are blown off, and the form of the wave becomes blurred. What's water and what's air...where is the top of the wave?
A simple related way to think about it from an observable perspective, is that at such small scales even if everything was smooth and well behaved, we need really short wavelengths...very high frequency... to be able to see anything...but that means high ENERGY...E = hf, so we disturb what we are trying to observe!
But the foam idea says it's already bouncing all around for very similar reasons anyway...lots of virtual energy at small scales...
http://en.wikipedia.org/wiki/Quantum_foam
all check: vacuum energy, zero point energy, Planck scale, Infrared-ultraviolet connection, Heisenbery uncertainty, etc...all related concepts.
and any SEE ALSO links that interest you at the bottom of any Wikipedia articles.
tom.stoer said:There are many indications for spacetime-discreteness: holographic principle, T-duality in string theory, spin networks in LQG, even in the asymptotic safety program something like an effective cutoff may emerge from a smooth manifold.
But these are mathematical models only and none of them has a chance of becoming directly (!) accessable experimentally.
Nano-Passion said:Or do we have no idea?
Naty1 said:We have no idea.
Nobody knows exactly what space or spacetime actually is...
My own suspicion is that it is likely discrete because at Planck length and smaller, about 10-33 cm quantum foam seems to destroy conventional ideas of space,time,matter,etc.
But the continuous perspective works very well in most of classical physics...like relativity.
Nano-Passion said:Or do we have no idea?
This shows is a duality between discrete and analog representations that are and bandwith limited; but the information content is finite.marcus said:Sample quote:
"The equivalence of continuous and discrete information, which is of key importance in information theory, is established by Shannon sampling theory: of any bandlimited signal it suffices to record discrete samples to be able to perfectly reconstruct it everywhere, if the samples are taken at a rate of at least twice the bandlimit."
One question where people seem to differ is: what is the ontological status of this "network of measurement results". This is exactly where I personally have problems with rovelli's logic.marcus said:Space consists of geometrical measurements---it is not a material substance, it is geometry.
Or so I think anyway. Space is a network of geometric relationships.
So when you ask questions like discrete/continuous, I would say you are asking questions not about a a physical material but about measurement itself. Measurement of areas, measurement of volumes. Observers. Observables.
Fineliner said:Purely theoretical there could be more bigbangs more then we will ever be able to observe (too far away), in such a case space and time might not be made by it..
It could have been always there and even have no beginning, empy space just exist (and wel basicly empty space is nothing so why wouldn't nothing exist not ?..
oops ...now it becomes rather philosopical.
You know its far more easy to think of someone made brick wall at the border.
Although you might fear what would happen if the walls break down
And don't put windows in this wall, they would only make you wonder who is looking through them...
The answer to this question is still unknown and is a subject of ongoing research and debate among scientists. Some theories suggest that space is continuous, meaning it has no breaks or gaps, while others propose that space is made up of tiny building blocks called quantums. However, there is currently no definitive answer.
One of the main pieces of evidence for continuous space is the concept of infinity. If space is continuous, then it must be infinite, meaning it has no boundaries or edges. Additionally, theories such as Einstein's theory of general relativity and the concept of gravitational waves also support the idea of continuous space.
The idea of unknown space highlights the fact that there is still much to learn and discover about our universe. It challenges us to continue exploring and pushing the boundaries of our knowledge. It also raises questions about the nature of our reality and the limitations of our current understanding.
It is impossible to know for sure if we will ever fully understand space. As our technology and understanding of the universe advances, we may continue to uncover new mysteries and complexities that we could not have previously imagined. However, the pursuit of knowledge and understanding is a fundamental part of science, and we will continue to strive towards a deeper understanding of space.
The concept of continuous or unknown space may not have a direct impact on our everyday lives, but our understanding of space and the universe has led to many technological advancements that benefit us. For example, our understanding of gravity and the laws of physics has allowed us to develop technologies such as GPS and satellite communication. It also inspires curiosity and wonder, which can have a positive impact on our mental well-being.