Monty Hall, with the earthquake... and musings

...further to my last post...

So, when Monty opens the door, that does not alter the probability that the prize was in (b) - the two non-chosen doors. We know that regardless of whether the prize is in (a) or (b), he's not going to reveal the prize when he opens the door. When he opens the door what it does is guarantee that if it was in (b), it is now behind the one remaining (b) door, which now has the whole of the 2/3 probability to itself.

But, when the earthquake opens one of the (b) doors and shows the prize is not there, that does alter the (b) probability. The earthquake might have revealed the prize, but it didn't, so what it tells us is just that it's not behind that particular door. The prize is not behind that door but is equally likely to be behind either of the others. The (b) probability drops to 1/2 and the (a) probability increases to a half.

David Mackay has a much more rigorous explanation*. However, my point is that while I am now fully convinced that I 'understand' what's going on, my initial intuition has been twice overturned. For a while previously I was fully confident of the opposite opinion. So, how can I ever trust what I earnestly believe to be true? New insights might overturn what I believe. It's back to this idea of the provisional again. What we believe can only ever be provisional. That's the only knowledge on offer.

* If you want to read it, David Mackay has made his excellent book available for free download here. The problems are on page 57 and the solutions on page 61.

Water into Watts

Another story of someone finding a way of getting unlimited power from water - but this one's backed by $60 million! I saw it in a paper in IEEE Spectrum:

Imagine that you could make hydrogen atoms do something that quantum mechanics says they can’t: slip into an energy state below the ground state, the collapse releasing 100 times as much energy as you’d get by just burning the hydrogen. If you could harness the heat to produce power, using hydrogen from water as fuel, you’d consume no oil, create no fumes, and solve the problems of energy and global warming forever.

Of course, first you’d have to overturn a century’s worth of physical theory, prove your point experimentally, and demonstrate its feasibility in a prototype power-producing system. Yet this is precisely what a company called BlackLight Power says it has done. The company, based near Princeton, N.J., has raised US $60 million, equipped massive labs, hired two dozen employees, gotten some high-profile executives to serve on its board, and attracted a devoted following of fans to online discussion boards.

Unlimited power from water (like 'the car that runs on water') is a staple of the popular press and a favourite of DIY 'inventors'. By and large, I think these claims are nuts. (We touch on this in the block on power for digital media in the new course T325: Technologies for digital media in the context of fuel cells for portable products such as laptops - there have been claims of cells that 'run on water'. In fact these cells do work and you do add water to keep them going, it is just that the energy isn't coming from the water, it is chemical potential energy in something else already in the cell. Saying it runs on water is sort of true but misleading.)

Anyway, back to the $60 million funding of something that requires the last 100 years of physics to be wrong for it to succeed. What I am wondering, is why I simply do not believe it, whereas clearly lots of people do. I'm quite confident in NOT believing it, and find the $60 million funding depressing. I have an undergraduate degree in physics but I don't claim that makes me an expert - I know I have pretty much no grasp of string theory, to take one example. So, it is not that I can honestly say that I, personally, can prove that the Hydrino theory is wrong.

Meadow says:

How do you come to have faith in a source or in a scientific test or procedure? Generally, you have learned from experience that a person, publication, or a broadcaster tells the truth or because someone that you trust encouraged you to believe in the source.

I suppose that is it: I have developed trust in the sources that tell me quantum mechanics is true (sort of), but I have no reason to trust Randell Mills of BlackLight Power. Most of the people I know would, I believe, instinctively agree with me. Indeed, I think a lot would wonder why I'm wondering about it at all: it is clearly rubbish and so what if a load of daft-but-rich people in America support it? But, I don't know, that seems like evasion. There are things taken as conventional wisdom that I don't want to sign up to, so how do I decide?