My sister’s new school book (physics, grade 11th) is introducing them with certain aspects of physics and it mentions unification in physics. it does not really say much about it that might be clearly understandable to me but I would like to know more about it.
does it mean there exists one equation which can be used for all problems? or will it link all existing theories? how will it be possible for equations of electricity to explain the equation of velocity?
In: Physics
Unification doesn’t actually mean that all problems are solved with a single equation. For example, if you drive twice as fast as your friend, you’ll still need to solve for the total distance with the same algebra we’ve always used.
Unification (“Theory of Everything”) refers to the theoretical description of the four fundamental forces of nature: gravity, electromagnetism, strong nuclear force, and weak nuclear force.
There are many reasons to suspect that those 4 forces are not as separate in nature as we might think, but rather are like different manifestations of a single physical law.
One major success in unification was the combination of two forces — electromagnetism and the weak nuclear force — into a single theoretical framework for a single fundamental force called “electroweak.”
On the face of things, it might seem completely bonkers to say that a massless photon has anything in common with a short-lived massive particle called Z. But through electroweak theory, these particles can be shown to be alllllllmost twins.
That area of physics is already in textbooks. The Z was discovered way back in the 80s. They wouldn’t have even tried looking for it if it hadn’t been predicted by electroweak theory.
A major piece of electroweak theory required some unobserved parts of physics to fall into place. So it was predicted that there must be a new type of particle that explains the theory’s so-called “Higgs mechanism”. The Higgs particle was experimentally confirmed at CERN in recent years.
Einstein spent decades fruitlessly testing ways to combine gravity with electromagnetism. But with our current perspective, we know he was fighting a losing battle. Gravity is notoriously hard to incorporate theoretically with the other forces. Throughout the ’80s and ’90s, it was hoped that String Theory would mature, and show us they way forward. It didn’t work out that way.
Theoretical physicists and experimental physicists are currently working on “Higgs sector physics” to better understand whether there’s one type of Higgs particle or multiple types, and if so, what their attributes are.
Physics is all about finding a set of rules which you can apply consistently to the universe so that in any given situation you can use those rules to predict what is going to happen. For instance if you let a hammer drop on a planet with a gravitational field the hammer will fall to the ground and not shoot up into the air. However there are currently some rules which don’t work equally on the large scale and the very small scale so physics is looking for a theory or theories which unify the rules.
I’m not sure what exactly the textbook was trying to say, but one big open problem in physics right now is the problem of finding a theory that would describe physical processes on all scales. It’s more about the second question you ask (linking existing theories), rather than just finding some magical single equation that explains everything.
To severely oversimplify the problem, we have an extremely well confirmed theory of how things behave on small scales (quantum mechanics). This theory explains and describes things like atoms, photons, and subatomic particles to an amazing degree of accuracy. For example, the periodic table of elements in chemistry comes from the laws of quantum mechanics.
We also have an extremely well confirmed theory of how things work on very large scales (general relativity). This theory explains and describes things like gravity, planetary motion, the behavior of light as it travels through space, the life cycles of stars and galaxies, and other things that involve large scales and/or long times. The predictions of this theory have also been confirmed to an amazing degree of accuracy.
However, there are some major problems that occur when the two theories are combined. For example, although general relativity predicts the existence of black holes and describes their features very well in some ways, it starts to break down when describing the microscopic features of black holes. Similarly, quantum mechanics doesn’t always make sense when we try to apply it to things on very large scales (for example, the universe itself in the case of things like the Wheeler-DeWitt equation).
To overcome these problems and find a theory that really works for all physical phenomena on all scales, we need a theory of quantum gravity. There is a lot of controversy about how to find a theory of quantum gravity, and which theories might be the best candidates as theories of quantum gravity. Two popular examples are string theory and loop quantum gravity. If you want to read more about this I would recommend looking at this page (https://en.m.wikipedia.org/wiki/Quantum_gravity). The book Trespassing on Einstein’s Lawn by Amanda Gefter is also great.
I’m assuming it means a grand unifying theory that explains standard and quantum physics. String theory may or may not be that unifying theory, but there’s a lot of research that still needs to be done. Because particles at the quantum level appear to defy our normal laws of physics, people are searching for a theory of physics that can account for that unexpected behavior.
https://en.m.wikipedia.org/wiki/Grand_Unified_Theory
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