Loop quantum gravity
Does loop quantum gravity exist?
Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. Research in loop quantum gravity today forms a vast area, ranging from mathematical foundations to physical applications.
What is the difference between loop quantum gravity and string theory?
In loop quantum gravity, or LQG, space-time is a network. ... String theory requires that space-time have 10 dimensions ; LQG doesn’t work in higher dimensions. String theory also implies the existence of supersymmetry, in which all known particles have yet-undiscovered partners.
What’s wrong with loop quantum gravity?
The biggest flaw in loop quantum gravity is that it has yet to successfully show that you can take a quantized space and extract a smooth space-time out of it . ... The quantum theory of space-time in loop quantum gravity is really just a quantum theory of space.
What is quantum string theory?
String theory describes how strings propagate through space and interact with each other . ... In string theory, one of the vibrational states of the string gives rise to the graviton, a quantum mechanical particle that carries gravitational force. Thus string theory is a theory of quantum gravity.
Why does string theory require so many dimensions?
Any more dimensions would result in too much supersymmetry and a theoretical structure too simple to explain the complexity of the natural world . This is reminiscent of Joe Polchinski’s argument (somewhat tongue-in-cheek, somewhat serious) that all attempts to quantize gravity should eventually lead to string theory.
What does the M in M-theory stand for?
M-theory is a theory in physics that unifies all consistent versions of superstring theory. ... According to Witten, M should stand for “ magic” , “mystery” or “membrane” according to taste, and the true meaning of the title should be decided when a more fundamental formulation of the theory is known.
What are the 26 dimensions?
The 26 dimensions of Closed Unoriented Bosonic String Theory are interpreted as the 26 dimensions of the traceless Jordan algebra J3(O)o of 3×3 Octonionic matrices, with each of the 3 Octonionic dimenisons of J3(O)o having the following physical interpretation: 4-dimensional physical spacetime plus 4-dimensional ...
How many dimensions are there?
The world as we know it has three dimensions of space —length, width and depth—and one dimension of time. But there’s the mind-bending possibility that many more dimensions exist out there. According to string theory, one of the leading physics model of the last half century, the universe operates with 10 dimensions.
Is the universe a loop?
Instead of being flat like a bedsheet, our universe may be curved, like a massive, inflated balloon, according to a new study. ... So it’s been largely rejected in favor of a “flat universe” that extends without boundary in every direction and doesn’t loop around on itself .
Why does string theory require 11 dimensions?
In string theory, the multiverse is made of different dimensions but the highest is 11th dimension. Beyond 11 dimensions, the universe would become unstable and dimensions higher than 11 would collapse to an 11-dimensional universe .
Who proposed loop quantum gravity?
In 1986–87, physicist Abhay Ashtekar completed the project which Amitabha Sen began.
What is loop quantum gravity?
Loop quantum gravity (LQG) is a theory of quantum gravity , which aims to merge quantum mechanics and general relativity, incorporating matter of the Standard Model into the framework established for the pure quantum gravity case. ... Consequently, not just matter, but space itself, prefers an atomic structure.
How many dimensions do we live in?
In everyday life, we inhabit a space of three dimensions – a vast ‘cupboard’ with height, width and depth, well known for centuries. Less obviously, we can consider time as an additional, fourth dimension, as Einstein famously revealed.
What are the 10 dimensions?
- Length. ...
- Width. ...
- Depth. ...
- Time. ...
- Probability (Possible Universes) ...
- All Possible Universes Branching from the Same Start Conditions. ...
- All Possible Spectrums of Universes with Different Start Conditions.
How many universes are there?
There are still some scientists who would say, hogwash. The only meaningful answer to the question of how many universes there are is one, only one universe .
