Friday, August 26, 2011

The "standard model" explained

Nice piece in today's The Conversation that starts;

The “traditional” beauty of theoretical physics is its equations. If we want to describe something, or the way something behaves, we can write down a relation between some properties we think that thing will obey.

The simplicity and symmetry of these equations – to someone who understands them – is amazingly beautiful.

So far so good. Yes that is a joy of Physics.

But the piece goes on to say;

Given the mass of a ball, the height, angle, and strength with which it is thrown, physics will tell you the path the ball with take through the air, how long it will be in the air for, and how far away and how hard it will hit the ground.

Physics can fully describe this system with just a few simple properties.

But, of course, it can't. Projectile motion happens in the real world so on top of the simple model based on initial velocity and gravity you need to allow for air resistance. The next simple iteration is to assume air resistance is proportional to velocity and tweak the model.

But real atmosphere has "winds" - and they are incredibly complex systems that can only be modelled statistically.

The system cannot be "fully described". It can be "satisfactorily described" for most practical purposes - including artillery attacks, dropping bombs and shooting rockets into space.

All these little perturbations matter when you get down to the level of particle physics.

The "standard model" of particle physics is both well described but also fails to account for all empirical results and has too many variables to really be a meaningful "explanation".

The search goes on for something better. I can't help wondering whether the physicists are all looking in the wrong places because they still believe this stuff about their ability to "fully describe" any system.

Note: An unfortunate side effect of this is that economists believe economic science can "fully describe" the economic system.

Novae Meridianae Demetae Dexter delenda est

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