Strange but true: the expanding Universe doesn’t conserve energy
Credit: NASA, ESA, P. Oesch (University of Geneva), and M. Montes (University of New South Wales)
Farhan Juratli shared this article. I'll try to write some background and leave it up to you to read the entire article.'
Background: My comprehension
The expanding universe has piqued people's interest. I recently wrote a note about energy conservation in the expanding universe. I presented my ideas about 2 days ago and concluded that the laws of energy conservation - the first law of thermodynamics - would still hold true in the expanding universe. Because the universe has no surroundings where it can do thermodynamic work and lose energy, I simply concluded that the total energy or enthalpy, H = U, equals the internal energy.
I also concluded that this may reduce the energy density of the universe, which may reduce the stored potential energy on Earth, raising the temperature on Earth.
Based on my study, I explained that the universe is experiencing an energy push-pull between the gravitational forces acting between galaxies and the mysterious dark energy that is sucking the energy of the universe and pulling the galaxies apart by sucking the energy of the universe.
What is the universe? How NASA defines the universe?
“The Universe is a big, open place. You are in the Universe. Things you can't see are in it, too. The biggest stars are in it. Even the smallest things on Earth are part of the Universe. We don't even know how big the Universe is!
Scientists study the Universe. They look at the stars and planets. They are called astronomers. They want to find out the size of the Universe. They don't know the answer, yet. But they do know it is still growing.
The Universe started long ago. It is still getting bigger today. We do not know if it will stop. Will it change direction? Or, will it keep going forever?”
What is dark energy? How the universe is expanding?
The universe is full of matter and the attractive force of gravity pulls all matter together. Nobody expected or understood how the universe is expanding in spite of so much gravitational attraction between matters in the universe. Eventually theorists came up with explanations. One of the theories is that maybe there is some strange kind of energy fluid that filled space. This was named dark matter.
Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect, or emit electromagnetic radiation and is, therefore, difficult to detect.
We call that mysterious force “dark energy”. Despite the name, dark energy isn’t like dark matter, except that they’re both invisible. Dark matter pulls galaxies together, while dark energy pushes them apart.
Dark energy does not have any local gravitational effects. This leads to a repulsive force, which tends to accelerate the expansion of the universe.
The article: Strange but True: the expanding Universe Doesn’t conserve energy
The key points in the article
-The conservation of energy is one of the most important laws in all of physics: energy can change forms but can never be created or destroyed. At a fundamental level, however, that is only true because the Universe obeys an underlying symmetry: time-translation symmetry, which states that everything is the same from one moment to the next. Only in the expanding Universe is this not true: the Universe changes from one moment to the next. As a result, energy is not conserved, which has truly cosmic consequences. Cosmic rays provide matter from outside the solar system. They are high-energy particles that move through space at nearly the speed of light. Most cosmic rays are atomic nuclei stripped of their atoms with protons (hydrogen nuclei) being the most abundant type but nuclei of elements as heavy as lead have been measured.
You can read the paper here