There are two sources of apparent randomness. First is the probabilistic nature of quantum mechanics, with fundamentally non-deterministic randomness. For example, radioactive decay is a random process, even though the expected half-life emerges from many such events. Though Einstein protested, it appears that God does play dice. (Maybe someday a successful Planck-scale string theory will reveal some hidden deterministic mechanism underlying quantum randomness? Don't hold your breath -- you'd need an accelerator bigger than the solar system!)
Then there are non-linear dynamic systems with chaotic behavior, which are deterministic but nonetheless completely unpredictable. You can't really call them random because of their deterministic nature, being completely governed by known equations, but since every real-world input is known only to a limited precision, and since these systems display "sensitive dependence on initial conditions" (butterfly effect), they are effectively unpredictable, much the same as pseudo-random computer algorithms that produce numbers with statistical properties of randomness even though completely deterministic.
For example, a rock tumbling down a cliff is always governed by Newton's law, but because the detailed geometry of all the contact points cannot be precisely known, its path is rendered unpredictable as if random. Some water faucets drip at time-varying rates that are also unpredictable, even though governed by known equations. Essentially it's why we can't exactly solve a three-body problem in gravitation.
At human scale, chaotic physical systems seem to be everywhere -- most real-world objects have interacting parts that introduce non-linearity that usually gives rise to chaotic behavior in the mathematical sense. (The book to read is "Chaos" by Gleick.) = copied
It hasn't had a singularity for nearly 50 years.>>
Are you saying that you're nearly 50 years old?
What I said wasn't about me. It was about the fact that the standard model of cosmology had inflation added in the 1970s. While people refer to this being very early in the Big Bang, there is no bound on how long inflation lasted, nor any knowledge of anything that might have preceded it (information is effectively eradicated by inflation).
It's all downhill now, you know. At 45 I could still play football for three hours. Now, 23 years later, I can barely crawl out of bed.
Son also got an MMath (1st) from Newcastle, and the physics bit was at St Andrews. He once told me that he thinks physics PhDs are easy and hard, or "soft" and "useful". He thinks that a relatively average person can get a physics PhD if they're lucky with their assignment.
LOL. The average person can't pass A-level physics, so your son is very generous.
He also thinks that the less able tend to be drawn to cosmology for the reason that it's much harder to get real evidence which will prove them wrong. So actually I got the impression he doesn't have too much respect for cosmologists.
My experience tells me that people are driven to what attracts them most and the appeal of the branch of science that deals with the history of everything we can observe is clear. It is the biggest subject of all ("subject" in the sense of that which is studied).