In a world where exploring the future means unraveling the past, Loop Quantum Gravity is no doubt another competitor for the search of a universal unified theory, a master theory, an ultimate theory that links together and attempts to give us purpose for our very own existence. It would be that one theory which allow classical and quantum physics to seamlessly intermingle with each other to create a skeleton with a backbone holding all the laws of the universe together! On the search for such an elegant theory, we are faced with paramount paradoxes that kept stumbling upon us. Will the Loop Quantum Gravity theory prove to be another loophole in our search for a unified theory where the mathematics of it doesn't fall apart?
The Loop Quantum Gravity theory is one of the most misunderstood theories out there because it tends correlates with String Theory which simplified, is a framework of the universe depicted in strings. To begin with, we live on a planet where particles are infinitesimally small. Unfortunately, we can't measure these fundamental elementary particles precisely of their position or velocity due to Heisenberg's Uncertainty Principle. However, Loop Quantum Gravity allows us to interpret gravity as not a force, but a property of Space-Time.
Quantum Loop Gravity takes Einstein's general theory of relativity by redefining gravity itself with nodules and links. But the problem arises when we attempt to grasp this as a whole picture...that is...if we could ever see this whole picture. Let's go a few steps back and revisit those nodules. This theory tells us that unlike what Einstein expresses as a geometric fabric called Space-Time, which is a continuum, states that instead it is made up of small discrete quanta. Imagine space-time made up of a finite number of loops, just as its named. Wherever these loops tend to intersect each other, they form nodes.
Similar to the picture above but with loops instead.
Now, when you look at these loops from a larger scale, you form a Spin Network of these loops which provide a more structural and geometrical comprehensive understanding behind the fabric of Space-Time. But what would "time" be in these spectacular networks? Time would therefore be the movement required to arrange, or shape this Spin Network. When we eventually combine time and these structural loops together, we give arise to the term Spin Foam. However, just as we have described Space-Time ever so discretely in terms of quanta, these intricate details such as their quantized discrete values are roughly estimated to be:
MINIMUM LENGTH: 10^-33 cm
MINIMUM AREA: 10^-66cm
MINIMUM VOLUME: 10^-99cm
MINIMUM TIME: 10^-43 seconds
These values play a role as the important lower limits of the parameters while analyzing a more geometric understanding of space-time.
Quantum Loop Gravity has Background Independence; a core fundamental in which Einstein highlights in the general theory of relativity illuminating the idea of how mass creates a distortion forming a space-time curvature. There would be no background unless these loops build it through a spin network. Similarly, the spin foam becomes distorted when exposed to mass and energy giving the arise of the concept of gravity. In this case of describing gravity, the nodules of the loops undergo a change in volume when they distort as similar to warping of space-time but in which due to time, affect movement of the volume quanta. So, in a way, we can say that Loop Quantum Gravity is an extension of The General Theory of Relativity.
This compelling theory offers us a theoretical approach as to how we can finally merge general relativity with the quantum field theory. An even more marvelous approach to this theory would be String theory where it goes on to escalate into 11 dimensions! (10 + 1 including time)
Unfortunately, the Loop Quantum Gravity theory doesn't have the capacity to hold its dynamics in such complex states. Moreover, the quantum constraint such as the Hamiltonian Constraint which brings in spatial and time diffeomorphism, which in short, regulates the parameters of these 3D spaces between the loops. In addition, even though this theory seems to bring us some satisfaction in the quantum field, the bigger questions need be tackled. What holds for Loop Quantum Gravity in the fourth dimension? Does backgrtound independence still hold as we progress forward? Does this theory still give us those equations at a larger scale? How close are we to proving it practically through experimentation? Unfortunately, these questions still remain a mystery at large.
The beautiful mathematics weaving this theory together helps brings us even closer to our universe than before. Perhaps in the future there would be fewer loopholes in our expedition for a theory that unites the universe together.
Check out the link below to learn more about findings on Loop Quantum Gravity!
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