Loop Quantum Gravity

The inability of scientists to create a theory of quantum gravity arises from long-standing tensions between general relativity and quantum mechanics. There have been few approaches with any success. In this video, Fermilab’s Dr. Don Lincoln explains one of the few promising ideas, called loop quantum gravity.

Further reading:

[FreshBeatles]

Dr. Lincoln, I don't know if you will ever see this, but I want you to know that your way of speaking and body language strangely make you easy to listen to and understand. I would not grasp these subjects as easily if it weren't for you. Thanks

[poposterous]

According to loop gravity, the frame rate of the universe is 6 x 10^44 quantum intervals per second.

That's 600, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000 fps.

[RaoulBorges]

Interestingly, there is a very important, but I fear, very underappreciated, part in this video:

Do I believe in Loop Quantum Gravity?
No, of course, not.
There's no confirming data.
But it's a fascinating idea and I'm very interested in finding ways to test it.
If Loop Quantum Gravity is real, I'm sure we'll figure it out and, even if it's not, the journey will be fascinating.

That's a very good, and very powerful description of what a scientific mindset should be.

[andybeans]

The only thing more mind-blowing than LQG is trying to imagine the sort of cocktail party that Don frequents.

[Perryman]

Does this mean we can finally measure coastlines???

[Notaweebiswear]

I'm not sure if any of you are big readers but there is an amazing book on Quantum Space by Jim Baggot. He collaborated with some philosophical physicists and explains a lot about this subject. I could see a lot of parts mentioned in this video, great job on the understandable delivery!

[AliHSyed]

I do love the idea. Although I don't know what's crazier, that space and time are quantized, or that they are absolutely continuous. Confirming either would truly blow my mind.

[tonkroese]

Diffeomorphism Invariance for dummies: what happens in Vegas stays in Vegas.

[DCDevTanelorn]

Please don’t let it end here. Quantized space time deserves more videos!!!

[adamkendall]

I was at a cocktail party and I used diffeomorphism invariance in a sentence and I got slapped by a lady then ejected from the club. The bouncers used my head to open the door. Did I not use it properly?

[quahntasy]

Thank goodness someone finally did a video on Loop Quantum Gravity!

[PublicCommerce]

I think it is appropriate that they use footage of Adderall to illustrate the concept of discrete mathematics.

[RenoYeh]

7:05 I think here exists an error, from what I've read they predict higher energy light travels slower.

[jamesblank]

Just because something is a "cool idea" without any observational evidence doesn't mean scientists should be spending time on it. This state of physics saddens me greatly.

[buddychadwick]

Thank you for this contribution to internet knowledge. Too many wanna be experts pushing out material. Nice to see an actual expert make a clear video

[lando]

At 6:17, what does it mean to add mass and energy? Are we adding the two parts together or adding them into an equation?

[dlbattle]

But isn't the momentum, and therefore the wavelength, in a juxtaposition of states until it interacts with the measurement device? Why would you expect them to travel at different speeds before that interaction?

[fightocondria]

What year is "Don't forget! Uli's Goodbye Cake! 2:30pm" from?

[dachew]

Dr. Lincoln, thanks for the awesome video. I love learning about our amazing universe, and I really enjoy your presentations. Go physics!

[agamemnongames]

I have a problem with this theory.

My problem is based on how the theory is explained in the video.

In logic, for something to be true, it must exist or be real.

Using Discrete mathematics seems to ignore the "paper."

This presumes the paper is not real.

If the paper is not real and the equations exist on the paper then anything on the paper [the plane] cannot exist either. The existence of the equation is dependent on the paper. Applying this to real space and real-time, the plane is space-time. If you are removing the paper then you are removing the plane of space and therefore the equations that exist in space-time cannot exist.

In logic, the deduction [possibility] and the induction [probability] have to agree. You cannot have truth in induction and have non-truth in deduction.

Also, science is a system. For Loop Quantum Gravity to be real then it must exist within space-time and the science and philosophies too.

Science is a philosophy. Mathematics is a philosophy.

However, in reality, equations do not exist. Paper exists. My bias here is that I think there are only six dimensions in the universe. They are point, line, plane, the lesser infinity, and the greater infinity.

The Lesser infinity is zero or undefined. Which I believe is living energy. The greater infinity is a number that has not been realized by Man. This is undefined too.

I think it comes down to a person's fundamental belief in the universe. Do you believe the universe is a stationary thing and that particles suddenly without any reason acquire energy? And that an ultimate state of rest must exist?

My thought is and this is my own theory, that formless Energy exists everywhere. Energy is infinite. And the universe is a finite thing that exists inside the environment of energy. I term this lesser infinity and greater infinity.

I think Loop Quantum Gravity is going in the right direction but it ignores reality.

Our universe is moving at the constant speed of energy. Because the universe is moving through the formless energy field it induces friction at the sub-atomic particle scale. Keep in mind that the thing that is actually moving is the matter. Energy does not move. Matter is finite. matter takes up space. Once you can measure it, the matter has gained enough energy to form photons through the Higgs Fields.

I call the smallest form of matter ether.

I do not know what that number is or how to determine it.

I think that why gravity and the speed of energy are constant everywhere in the universe is because the universe is a big ball moving through an energy field that cannot be measured. I believe that we are never going to know what the greater and lesser infinity numbers are going to be. They are not measurable because they do not take up space or have mass. In the universe, mass and energy are exchangeable because there must be an equivalent amount of matter with energy to be measurable or to be an observable thing.

[I used to think the universe was a torsal shape, however, I have moved to a ball shape]

Second to my theory I think light does not actually move. I think the universe is moving and what we see is the friction or inducement of that friction. I call it 'the after-effect."

I study psychology and if you study contour lines and how the human eye perceives them then you understand they do not really exist in the universe. Contour lines are the product of the human eye. It is a process known as lateral inhibition.


The Loop Quantum Theory seems to want to ignore reality for the math to work.

Sidenote, the part where I included my theory is so you understand where my biases are or how they are derived. But circling back to my second point. At the quantum level of the universe or quantum scale, it really comes down to what you believe as a scientist and a human being. I believe that energy is alive and has intelligence. It is a massive organism.

However, if you believe the universe is just a dead thing and stationary and in a permanent state of rest. Since I subscribe to the previous belief, that theory makes sense to me. The second theory does not make any sense to me.

I hope my words and my meaning are clear.

Thank you.