How Our Universe Violates a Fundamental Law of Physics! Energy Conservation
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Published 2023-06-18
REFERENCES
General Relativity: • General Relativity Explained simply &...
Dark Energy: • What is Dark Energy made of? Quintess...
History of the universe: • A Brief History of the Universe! All ...
All Physics Explained: • All physics explained in 15 minutes (...
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CHAPTERS
0:00 Energy only changes form
1:19 Open vs Closed vs Isolated system
2:39 Is the universe an Isolated system?
3:50 What General Relativity says about energy conservation
6:00 Evidence for Violation of Energy conservation
7:40 Could lost energy be transforming into Dark Energy?
8:50 If the Universe is infinite, then all bets are off
9:47 Even if not infinite, we are almost certainly losing energy
10:28 Opposing view on why Energy could still be conserved
SUMMARY
The law of energy conservation may be the most fundamental law in physics. It says that overall energy is always conserved. It can never be created nor destroyed - it can only change form. But this law is probably violated by our universe as a whole.
Specifically, the Energy Conservation law states that in an isolated system, that is a system in which no matter or energy enters or leaves, overall energy remains the same. Energy only changes form.
But isn't the entire universe a well-defined isolated system? Since the universe if everything, shouldn’t it be the ultimate isolated system? It turns out that the answer not straightforward. If we want to include the whole universe, we have to include everything from the very small to the very large. Let’s start with the very small. The behavior at the micro-scale is described by quantum mechanics.
At the quantum level, the concept of energy conservation is explicitly defined. This is shown in the Schrodinger equation, which states that total energy is equal to kinetic energy plus potential energy. Energy is conserved according to this equation. So there is no problem at micro scales.
But at the largest scales, where Einstein’s theory of general relativity applies, this is not the case. What his field equations show is that the derivative of the energy-momentum tensor is zero. So the simplified way to think of this is that the change in energy and momentum remains zero. This is called the principle of energy momentum conservation.
This equation is not saying that energy stays the same, only that the combination of energy AND momentum remains the same. This means that energy can change, as long as the combination of energy and momentum doesn't change. So, it tells us that at large scales, energy is really not conserved in the universe.
Several observations confirm this. First is the expansion of the universe. Empty space has energy. If the volume of this space is increasing then energy is increasing. We know that the energy density of spacetime doesn’t change, but energy density is energy over volume. If the volume increases, then energy also increases.
Another consequence of an expanding spacetime is the observed redshift. The light from distant galaxies is redshifted. As the universe expands, the wavelength of light also expands, which means it loses energy. So light is losing energy within an expanding spacetime from our perspective.
Could it be that the energy that light waves lose turns into dark energy, thus conserving energy overall? The answer is no. I explain why in the video.
In an expanding universe, we don't even know what the size of the universe really is, so we can’t define what the isolated system would be. We only know the observable universe, which is about 94 billion light years in diameter. But there is a cosmic event horizon which is the end of this observable universe. We don't know how big big the universe is beyond this horizon.
If the universe is infinite, then we would have to conclude that the universe likely does not conserve energy.
Evan if the universe is not infinite, it is probably still the case that it is much much larger than the 94 billion year diameter that we observe. We are losing energy of the galaxies that are moving out of the observable universe.
#energyconservation
Some experts believe that overall energy is conserved in an expanding universe because, they say, you have to include the energy of the gravitational field along with the energy of the matter and radiation. In other words, as distances between objects increase, the increasing gravitational potential between them, which is a kind of negative energy, also increases, balancing overall energy.
All Comments (21)
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I've read somewhere that conservation of energy is such an important concept in physics that each time it didn't seem to work energy was just hiding somewhere else and it lead to immense breaktroughs in physics. I hope this will be the case for this as well.
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My mind just exploded. That's a good thing. One valuable insight is that I don't understand momentum well enough. Thank you, Dr. Ash!!!
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Arvin, that is a great video. When we first intreracted, I told you my brain had suffered. Now it has melted. I can get much more out of your explanations. You're a really great presenter who knows his subject. I will add, your presentations have acquired a subtle gloss and a wonderful technical advancement. If we are to continue to attract juniors into the STEM subjects at school, we couldn't do better than making your series part of the curriculum. Learning is sometimes difficult, but if it is attractively and coherently presented, students will assimilate the information easily. Knowledge is power and we will need more and more science students to lead us into the future. Thank you for your keen interest and your work.
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Thank you for the video! Energy is the conserved quantity that arises from time translation symmetry. Our Universe as a whole doesn’t seem to have time translation symmetry.
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A wonderful, condensed video on a complex subject. I truly appreciate your simplification to accommodate the time. Thank you! I've been looking for a new video , concerns for your health after the long period of treatment/cap. Thanks
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Fascinating observations as always, Arvin!
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1:33 I have a BChE in chemical engineering and even I long forgot this clear distinction. I've seen Youtubers toss these words around but NOBODY stated the definitions THIS clearly like YOU did, Arvin Ash! Thanks!
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Good deal man,I always enjoy watching ur videos then thinking about the universe, keep making these great topics 😎
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I remember the first and second laws of Thermodynamics this way: 1. You can't win (matter and energy are always conserved; you can't get more out of a closed system than you put in; there's no such thing as a perpetual motion machine) 2. You always lose (entropy always increases, and also no perpetual motion machine) As for the third, "a perfect crystal at 0K has zero entropy," I'd not be able to remember even on a multiple guess quiz. But discrepancies occur at the small end, too. Certain quantum mechanical studies seemed to say that particles wink in and out of certain fields. We need to explore these.
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This is gold! You are a scholar and a gentleman my friend, love your content and your style.
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Thanks Arvin, for another well explained, interesting video.. Please keep on making them.
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great work, respect for your work sir!
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Finally, I have been saying this for quite a long time. Nice to hear someone else break it down.
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Sir Arvin thanks again for providing us all with such high quality videos , in the future I would like to work with you in Science field as it's my passion and I get really excited by it. I think that nowadays we are not having that many breakthroughs in science as compared to the previous century. It could be due to some reasons. I rarely comment, cos i think its not worth the time. But on your videos, i really love all your videos. GOD BLESS YOU, SIR😊
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Mind blown 🤯
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Thanks for another science-heavy video and breaking it down into smaller bits
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You're the best Arvin! Luv your content. I was wondering if you might consider doing a series on each (or at least the most commonly used) of the physics equations? Really break down each of the variables in what they represent, how they are measured/derived, and what is implied by their relationships. I know it sounds kind of dry, but folks like me would really appreciate it! Thank you 🤗 Or if there is a really good library of such content out there to freely access, please point me in the right direction, anyone.
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WoW...what a beautiful explanation
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Keep up the great work Team Ash! ^.^
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Awesome video! Seems like you addressed all the typical questions 👍
