Symmetry in physics
Published by admin September 12th, 2007 in Physics, Doctors of PhilosophyFrom1 Lie Groups in Physics:
Many systems2 studied in physics show some form of symmetry.3 In physics this means the following: We consider some transformation rule like rotation, displacement, reflection and we compare the original system with transformed system.4 If this shows resemblance5 we have symmetry.
A snow flake looks like itself6 when we rotate it by 60 degrees. We say that the snow flake has a symmetry.
If we replace a proton by a neutron, and vice versa, the replaced particles behave very much like the originals; this is also symmetry.7
Many laws of Nature have symmetries in this sense.
Only a physicist can write this meaningless sentence. What physicists call “Law of nature” is what stays constant as some other things vary, i.e., physicists call proportionalities laws of nature. But a proportionality is a statement of symmetry (as some things change some other thing stays the same).
Physicists call symmetry a law and then they say that law has symmetry!
Law, proportionality, symmetry are synonyms in physics. Only a scholastic doctor of physics can revel in such circular reasoning. Can there be a better proof that physicists are in the business of inventing scholastic labels and labels on labels and discuss their labels as laws of nature?
Sometimes the symmetry is perfect, but often it is not exact; the transformed system is then slightly different from the original; the symmetry is broken.
One of the defining characteristics of scholasticism is the murkiness of concepts. In scholasticism every label is speciated8 into finest possible graduation of meanings. So it is not surprising that in physics symmetry is a graduated concept and it can be broken into non-symmetry and physicists will still call it symmetry.
Symmetry is a concept of visual arts and mathematics. Physics comes in only when physicists use symmetry to study their occult forces.
- Lecture notes by Gerardus ‘t Hooft. Can also be found here. [↩]
- Warning: In physics “system” is a term of art that can acquire instantaneously any meaning that suits the present doctrines of the physicist. [↩]
- Symmetry defines the system or object not vice versa. [↩]
- He considers pre-transformed and post-transformed objects to be two different objects. There must be a philosophical term for this but I cannot remember now. [↩]
- this is a weak requirement. Just resemblance? A stronger match between pre- and post-transformation is needed. [↩]
- now he does not consider the same snowflake two different objects [↩]
- Physicists named the same item two different names and they surprise themselves when the same item behaves as itself. [↩]
- the famous hair splitting of scholastic doctors [↩]
I agree on this.
Physicists worship symmetry, but its use in physics is strictly utilitarian. It’s a mathematical trick that makes solving parts of difficult problems much easier. It gives quick answers without requiring the user to fully understand the problem, sometimes without even being able to write down the problem.
If you’re too stupid to solve a problem, symmetry is a great way to try to weasel out a little bit of the solution. But by itself it can almost never provide a complete solution; its use frequently indicates no true understanding of the problem.
The fact that it sometimes works is certainly no evidence whatsoever that nature is symmetry. What it is evidence of is that when a drunk loses his wallet at night, the first place he looks for it is under the lamp post. Symmetry takes out the soft underbelly of problems, but this success is not even proof that one understands the nature of the problem.
The phrase “broken symmetry” should be enough to convince the laymen that the standard model of physics, which is based on symmetry principles, is quite broken.