I learned this today. Cold fusion is not possible because atoms repel each other and thermo energy on the scale of millions of degrees is necessary to overcome this repelling force and drive them together.
Nuclear fusion is the reaction that takes place in stars. It is the process by which they burn their fuel, hydrogen. When all of their fuel is used up, the stars die. Nuclear fusion is the reaction where two or more atomic nuclei are fused together. For example, in a star, four atoms of hydrogen are fused together to make one atom of helium. Hydrogen makes up the fuel of most stars because it is the lowest element on the periodic table and the most abundant in the universe. When the 4 hydrogen atoms combine to make helium, there is a tiny difference in the weight, and this difference is released as energy. The energy is incredibly small, but if you have enough atoms combining, it adds up. Our sun uses 620 million tons of hydrogen to make 616 million tons of helium every second. That difference is energy.
To make nuclear fusion happen, you need to have enough heat to overcome the Coulomb force, or electrostatic force, between particles. Coulomb’s force was first written about in 1785 by Charles-Augustin de Coulomb, hence its name. He studied the repulsion and attraction forces of charged particles and he worked out that the repulsion force increases as the particles get closer together. To overcome this force and get nuclei close enough together that their nuclear force takes over and holds them together takes a staggering amount of energy. In a star, the mass of the star creates stupendous pressure that crushes the nuclei together and gives them enough thermo energy to overcome Coulomb’s force. This is typically at about 15 million degrees Celsius. On Earth, we can’t recreate the huge gravity of a star, so we have to use even higher temperatures to make nuclear fusion work. We need to make temperatures of over 100 million Celsius. It is possible to attain nuclear fusion here on Earth, but it takes far more energy to achieve fusion than can be got out of it. The goal is to make a fusion reactor that would sustain itself and produce more energy than was put it.
And that is what gave rise to the idea of cold fusion. Cold fusion would be fusion that operates at room temperature. If such a reaction were actually possible, it would mean that unlimited energy could be made without putting anything in except the fuel. The problem is that according to the laws of physics cold fusion is not possible.
A few scientists have claimed that they have been able to make cold fusion work over the last century, but it has always been impossible to replicate their experiments. They have been experimenting with deuterium, which fuses more easily than hydrogen, but with no replicable results. If it were working, the experiment should produce helium, heat, neutrinos, and gamma radiation, all of which are testable.
If cold fusion were actually possible, it would be the holy grail of energy production. However, because it would violate the known laws of physics, it has become a crazy fantasy in the science world. In fact, it is now impossible to register a patent in America if it is recognizably an attempt at a cold fusion device.
Some scientists are still researching the topic and in 2019 Google spent $10 million on research into cold fusion, but nothing was found. The name has been changed from Cold Fusion to Low Energy Nuclear Reactions to try to gain back some of the respectability.
Experiments that passed an electric current through a deuterium solution with a palladium lattice in it have produced neutrons and some heat. However, this is an electron capture process and not cold fusion.
However, just because it seems impossible is not a reason to stop researching, some people have said. A lot of things that we now know to be possible were considered impossible at some point. The laws of physics can not be broken until we learn of something that is breaking them.
So, nuclear fusion is the process where nuclei from four hydrogen atoms are crushed together in the high-pressure center of a star to form one helium atom, releasing energy. To combine the atoms takes an enormous amount of energy because it is necessary to overcome the Coulomb’s force which makes atoms repel each other. Cold fusion is not possible because there is no physical way of getting atoms to stick together without this energy. It goes against the laws of physics. And this is what I learned today.
By Stevenkrivit at the English-language Wikipedia, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=5766203
Sources
https://en.wikipedia.org/wiki/Cold_fusion
https://www.seeker.com/5-reasons-cold-fusion-is-bunk-1767562536.html
https://www.scientificamerican.com/article/what-is-the-current-scien/
https://en.wikipedia.org/wiki/Nuclear_fusion
https://en.wikipedia.org/wiki/Main_sequence
https://en.wikipedia.org/wiki/Coulomb%27s_law
https://en.wikipedia.org/wiki/Weak_interaction
https://science.howstuffworks.com/fusion-reactor2.htm
https://www.euro-fusion.org/fusion/fusion-on-the-sun/
https://medium.com/the-infinite-universe/cold-fusion-may-not-be-fusion-2e7238f38b80