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https://www.energy.gov/science/doe-explainsnuclear-fusion-reactions

https://www.nbcnews.com/mach/science/what-big-bang-theory-ncna881136

https://en.wikipedia.org/wiki/Georges_Lema%C3%AEtre

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Nuclear Fusion reactions power the Sun and other stars. In a fusion reaction, two light nucleimerge to form a single heavier nucleus. The process releases energy because the total mass of the resulting single nucleus is less than the mass of the two original nuclei. The leftover mass becomes energy. Einstein's equation (E=mc ²), which says in part that mass and energy can be converted into each other, explains why this process occurs. If scientists develop a way to harness energy from fusion in machines on Earth, it could be an important method of energy production.

Fusion can involve many different elements in the periodic table. However, researchers working on fusion energy applications are especially interested in the deuterium-tritium (DT) fusion reaction. DT fusion produces a neutron and a helium nucleus. In the process, it also releases much more energy than most fusion reactions. In a potential future fusion power plant such as a tokamak or stellarator, neutrons from DT reactions would generate power for our use. Researchers focus on DT reactions both because they produce large amounts of energy and they occur at lower temperatures than other elements.

DOE Office of Science & Fusion Reactions

The Department of Energy Office of Science, Fusion Energy Sciences (FES) program seeks to develop a practical fusion energy source. To do so, FES partners with other Office of Science programs. They work with the Advanced Scientific Computing Research program to use scientific computing to advance fusion science as well as the Nuclear Physics program on nuclear reaction databases, generation of nuclear isotopes, and research in nucleosynthesis. FES also partners with the DOE's National Nuclear Security Administration to pursue fundamental research on fusion reactions in support of DOE's nuclear stockpile stewardship mission.

Fusion Reaction Facts

The ITER international fusion energy experiment will be scientists' first attempt at creating a self-sustained fusion reaction for long durations. "Burning plasmas" in ITER will be heated by the fusion reactions occurring in the plasma itself.

Fusion reaction experiments at the DOE's National Ignition Facility at the Lawrence Livermore National Laboratory require 192 laser beams to align on a DT target smaller than a pea. This is like throwing a perfect strike in baseball from a pitcher's mound 350 miles away from the plate.

Resources and Related Terms

Acknowledgements
Matthew Lanctot (U.S. DOE Office of Science) Scientific terms can be confusing. DOE Explains offers straightforward explanations of key words and concepts in fundamental science. It also describes how these concepts apply to the work that the Department of Energy's Office of Science conducts as it helps the United States excel in research across the scientific spectrum.

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Another piece of evidence to support the Big Bang Theory is Red shifts. Red shifts is the tendency of waves to shift towards the red part of the light spectra when an object is moving away from you. For example, when looking at a galaxy that is moving away from you, the wavelength of the light coming from the galaxy would be shifting towards the red part of the light spectra. With this, astrologers have concluded that far away galaxies are moving away from us, supporting the statement that the universe is expanding, which is an idea of the Big Bang.

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https://www.space.com/24073-how-big-is-the-universe.html

https://www.sciencedaily.com/releases/2021/03/210308165239.htm#:~:text=This%20means%20that%20for%20every,1.4%20km%2Fsec%2FMpc.

https://physics.stackexchange.com/questions/484157/how-does-the-ratio-of-hydrogen-to-helium-help-prove-the-big-bang-theory/484170

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(Image: © NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team)

As technology has evolved, astronomers are able to look back in time to the moments just after the Big Bang. This might seem to imply that the entire universe lies within our view. But the size of the universe depends on a number of things, including its shape and expansion. Just how big is the universe? The truth is, scientists can't put a number on it.

The observable universe

In 2013, the European Space Agency's Planck space mission released the most accurate and detailed map ever map of the universe's oldest light. The map revealed that the universe is 13.8 billion years old. Planck calculated the age by studying the cosmic microwave background.

"The cosmic microwave background light is a traveler from far away and long ago," Charles Lawrence, the U.S. project scientist for the mission at NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement. "When it arrives, it tells us about the whole history of our universe."

Because of the connection between distance and the speed of light, this means scientists can look at a region of space that lies 13.8 billion light-years away. Like a ship in the empty ocean, astronomers on Earth can turn their telescopes to peer 13.8 billion light-years in every direction, which puts Earth inside of an observable sphere with a radius of 13.8 billion light-years. The word "observable" is key; the sphere limits what scientists can see but not what is there.

But though the sphere appears almost 28 billion light-years in diameter, it is far larger. Scientists know that the universe is expanding. Thus, while scientists might see a spot that lay 13.8 billion light-years from Earth at the time of the Big Bang, the universe has continued to expand over its lifetime. If inflation occurred at a constant rate through the life of the universe, that same spot is 46 billion light-years away today, making the diameter of the observable universe a sphere around 92 billion light-years. [ VIDEO: Oldest Light in the Universe: How it Traveled to Us]

Centering a sphere on Earth's location in space might seem to put mankind in the center of the universe. However, like that same ship in the ocean, we cannot tell where we lie in the enormous span of the universe. Just because we cannot see land does not mean we are in the center of the ocean; just because we cannot see the edge of the universe does not mean we lie in the center of the universe.

Even bigger?

Scientists measure the size of the universe in a myriad of different ways. They can measure the waves from the early universe, known as baryonic acoustic oscillations, that fill the cosmic microwave background. They can also use standard candles, such as type 1A supernovae, to measure distances. However, these different methods of measuring distances can provide answers.

How inflation is changing is also a mystery. While the estimate of 92 billion light-years comes from the idea of a constant rate of inflation, many scientists think that the rate is slowing down. If the universe expanded at the speed of light during inflation, it should be 10^23, or 100 sextillion.

Instead of taking one measurement method, a team of scientists led by Mihran Vardanyan at the University of Oxford did a statistical analysis of all of the results. By using Bayesian model averaging, which focuses on how likely a model is to be correct given the data, rather than asking how well the model itself fits the data. They found that the universe is at least 250 times larger than the observable universe, or at least 7 trillion light-years across.

"That's big, but actually more tightly constrained that many other models," according to MIT Technology Review, which first reported the 2011 story.

The shape of the universe

The size of the universe depends a great deal on its shape. Scientists have predicted the possibility that the universe might be closed like a sphere, infinite and negatively curved like a saddle, or flat and infinite.

A finite universe has a finite size that can be measured; this would be the case in a closed spherical universe. But an infinite universe has no size by definition.

According to NASA, scientists know that the universe is flat with only about a 0.4 percent margin of error (as of 2013). And that could change our understanding of just how big the universe is.

"This suggests that the universe is infinite in extent; however, since the universe has a finite age, we can only observe a finite volume of the universe," NASA says on their website. "All we can truly conclude is that the universe is much larger than the volume we can directly observe."

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(Image: © NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team) As technology has evolved, astronomers are able to look back in time to the moments just after the Big Bang.

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So What Happened To This Infinite Amount Of Heat, And Is This Infinite Heat Still Out There? + Why You Would Immediately Die If You Reached The Edge

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So What Happened To This Infinite Amount Of Heat, And Is This Infinite Heat Still Out There? + Why You Would Immediately Die If You Reached The Edge

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The heat coming from the infinite nuclear fusions isn't as prevalent anymore and is definitely not infinite... where we are. I'll get to it later. While I can't disprove or explain the theory that the universe is expanding faster, I can explain why it might be expanding at a constant rate. This takes us back to the prevalence of the infinite heat of these infinite nuclear fusions. From where we are right now, the ratio of hydrogen to helium is 3:1, or 75% hydrogen and 25% helium. And I believe it remains this way for pretty much the entire expanding universe, except for the outer edges. You see, an infinite amount of heat can't just fade away. It's infinite, it can't logically fade. So I believe that the outer edges of the universe are still infinite in temperature, which explains why it is still expanding, and why it is going to keep expanding until the universe has run out of matter. According to my guess, this means that we will probably never be able to get even remotely close to the edge of the universe since it would be infinitely hot, it would be brighter than anything in the universe, and since energy coming from nuclear fusion is released as electromagnetic radiation, it would horribly deform and disorient you before quickly vaporizing you from existence. As for how the center temperature of the universe isn't infinite when the outer edges are, I have no idea (yes, I admit, this theory has holes in it).

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So How Is Hydrogen Still Present In Our Time?

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So How Is Hydrogen Still Present In Our Time?

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I believe there are two scenarios (they're pretty simple, don't worry) that might have occurred that will explain why hydrogen still exists. Scenario #1: the infinite pieces of hydrogen wasn't all used up. Since nuclear fusion doesn't take the exact same amount of time for each occurrence, some hydrogen fragments, right before they were about to undergo nuclear fusion, were blown away by the infinite explosion, causing some of them to sort of weld back together into hydrogen atoms (well, when the universe cooled down enough), since the infinite pressure acting on them was not there anymore. Scenario #2: Hydrogen was fused back into existence. I don't like this one, because it's boring, but it's possible.

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So How Was The Universe Infinitely Hot, Infinitely Dense, and Infinitely Small?

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So How Was The Universe Infinitely Hot, Infinitely Dense, and Infinitely Small?

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This question is a bit tricky, so let me try to my best to dissect and explain it (because I can't find much on google). Let's start with size. If something is described as infinitely small, it means it is smaller than anything, it is smaller than the concept of measurement itself. For the universe to be infinitely small my only guess would be that it was insanely dense, like, much, much denser than a neutron star. Eventually this mass might have collapsed under its own weight since its matter might have been so compact that it would ignore the boundaries of other matter near it. This means all of the matter of this extremely dense object wasn't technically fusing (at the moment), but the matter instead sort of overlapped each other, meaning all of this matter would now have the same exact location in space-time, but would be separate things (and the matter I'm referring to is everything that something is made up of, meaning all atoms, electrons, neutrons, quarks). But, since half a quark is still considered matter, I believe infinitely small size-equal pieces of matter would be broken off, and the matter that would be overlapping each other would be these infinitely small pieces of matter. Since these pieces were somehow located in the same exact location in space-time, the size of these pieces would also be the size of this pre-Big Bang universe. This also solves the dense question, because if something is infinitely small, then it would also have to be infinitely dense. As for temperature, I believe that initially this premature universe was at 0 K, since if it was anything above absolute zero, then the matter would move, causing it to spread, which, according to my theory, can't be possible. However, I do believe that temperature was the trigger for the big bang. Let me explain. Hydrogen atoms were present in this premature universe, and when these infinitely small pieces of hydrogen sort of overlapped one another, they underwent nuclear fusion and it sort of used up most (most of infinity is still infinity) of these pieces of hydrogen, skyrocketing the temperature of the singularity from 0 K to ∞ K. And because matter starts to vibrate and move when its temperature is higher, this infinite amount of heat made all of the matter in this singularity start moving, causing the singularity itself to expand (sort of like what happens in a star). And this event of expansion in this singularity was known as the Big Bang.

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There is a surprising amount of evidence gathered by the scientific community to support the Big Bang Theory. One of the big pieces of evidence to support this theory is a type of radiation called cosmic microwave background (also known as relic radiation or cosmic background radiation) which is a supposed remnant of the big bang event. See, CMB was present around 400,000 years after the big bang event, in which the universe was one hundred-millionth of its size now, and it's temperature was 273 million K. It was so hot that any atom would immediately be broken down into small particles such as electrons and protons. The radiation from the CMB was scattered off electrons but were unaffected by the changes of temperature over time and remained intact through present time. However, the CMB has cooled so much that these rays are only 2.725 K above absolute zero. Because of their sheer temperature, they are most visible when put through the microwave section of the the light spectra (a.k.a. the electromagnetic spectrum). These historical rays are relics of the past, which very well may be the key to unlocking knowledge and confirming the existence of the Big Bang.

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https://www.space.com/25126-big-bang-theory.html

https://www.amnh.org/learn-teach/curriculum-collections/cosmic-horizons-book/georges-lemaitre-big-bang

https://www.space.com/33892-cosmic-microwave-background.html

http://physicsnet.co.uk/gcse-physics/red-shift/

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The Big Bang Theory explains how the universe began with an infinitely hot and dense single point that inflated to form the ever-expanding cosmos we see today.

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The theory was first acknowledged as an official scientific theory in 1931, however Lemaître had started developing the theory before 1927. He published his theory in a scientific paper in 1927 in a foreign language, however, which may have contributed to the lack of attention it got. In 1930, he told Arthur Eddington about his theory and Eddington was so astounded by Lemaître's findings that he immediately notified fellow cosmologists of Lemaître's paper and he and a group of cosmologists called for the publication of Lemaître's paper in english.

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The Big Bang Theory was a scientific theory developed by Georges Lemaître, a Belgian cosmologist and Catholic Priest. It basically states that before the universe was the way we knew it, it was an infinitely small singularity, which was also infinitely dense and infinite in temperature. However, a phenomenon known as the big bang caused this singularity to expand rapidly, and this singularity was then known as a universe. In fact, according to this theory, the universe still and will be expanding until the end of time (or until the Big Crunch happens but that's a different story).