Saturday, June 18, 2016

Physicists with faith in the multiverse

Peter Woit reports:
So, from the Bayesians we now have the following for multiverse probability estimates:

Carroll: “About 50%”
Polchinski: “94%”
Rees: “Kill my dog if it’s not true”
Linde: “Kill me if it’s not true”
Weinberg: “Kill Linde and Rees’s dog if it’s not true”

Not quite sure how one explains this when arguing with people convinced that science is just opinion.
Neil comments:
When a weather forecaster tells me the probability of rain tomorrow is 50%, I translate it as “I don’t know.” With a greater than 50%, I hear “There is more reason to think it will rain than it won’t” and vice versa with less than 50%.
No, this is badly confused.

If you really don't know anything, then you can apply the Principle of indifference to say that both possibilities have a 50% prior. But that is certainly not what the weather forecaster means. He is says that when historical conditions have matched the current conditions, it has rained 50% of the time. That is very useful, as a typical day will usually have a much less chance of rain (in most places).

A multiverse probability estimate does not refer to other instances that may or may not have been multiverse. So all the probability can mean is a measure of the speaker's belief. This is not any evidence for the multiverse, so it is like a measure of one's faith in God.

1 comment:

  1. Bayesianism is overrated and mathematics degrades public issues. Not only has it had a small role to play in invention, it causes a great deal of damage because it provides people with false assurances. Even over-optimization and bad management techniques result from mathematical perspectives. It's cheesy and corny and practiced by asperger types. They're not even that good at it. I have slowly moved into the "I hate math" camp over my life. It's so overrated and useless. I can't believe it gets any more respect than classical music. Add and subtract but the rest is controversial. There is no art in these people.