misc links

[gusl]

very good interview with Aubrey de Grey

MP3s from Tranvision 2003, including Aubrey's talk.



Really good tab site
http://www.cifras.com.br/

Physicists: is this yet another quack theory?
http://www.quackgrass.com/space.html

Comments

[spoonless.livejournal.com]

Physicists: is this yet another quack theory?
http://www.quackgrass.com/space.html

Don't know if quack is the right word, since it's more philosophy than physics. But I'd definitely call his opinions misinformed.

I wish I knew what definition of causality he was using, because I know he can't mean what physicists mean when they say "causality". The physics definition of causality is "any theory which does not allow signals to travel faster than light". The reason we define it that way is because sending a signal faster than light leads immediately to closed-timelike-loops, where you could have A affecting B and B affecting A recursively which is nonesense. A causes B causes A is self-fullfilling, and A causes B causes not A is self-negating. Either one is ridiculous, so we throw out any theories which violate (our definition of) causality in this way. I don't know why he seems to think relativity is anti causality because it is usually used as the ultimate enforcer of causality (even when other branches of physics start to lead scientists down the path of questioning causality, relativity keeps them in check.)

He says non-Euclidean geometry is just using "squishy lengths" instead of "rigid lengths" but that's not true, they are just as rigid. And there's no way to use a Euclidean metric on the parts of space which are curved, because you wouldn't get consistant results. For instance, if you measure the diameter of a large circle nearby a black-hole and then measure the circumference of the same circle (with the same rigid meter stick) their ratio will not be pi as Euclidean geometry predicts. There's no way to account for this with Euclidean geometry, unless you really did go to using squishy lengths.

Another part where he is completely uninformed about scientists' general opinions on things:
"We can now understand why relativists must postulate the speed of light in vacuum to be a universal constant. They equate vacuum with void; and if vacuum were nothing, there would indeed be nothing which could change the speed of light in vacuum! Relativists have no grounds to be smug about this fragment of consistency, for it comes at a terrible price: it banishes reason and causality from physics."

No physicists I know equate vacuum with void. An everyday layperson might think the vacuum is like a void, but to a physicist, it's far from empty... the vacuum is a sea of quantum foam, continuously bubbling and broiling and frothing with activity, creating and annihilating infinitely many pairs of particles all over the place at once. To call it a void would be a complete mischaracterization of how it's seen in modern physics. I don't know why he thinks it being or not being a void would be at all related to the speed of light being constant, but the reason the speed of light is postulated to be constant is because it was observed to be constant... to the great surprise of the physicists of the early 1900's.

[kvschwartz.livejournal.com]

Interesting you should use the word "frothing", because that sounds like a good description of writer of that web page. :p

On a side note: the Michelson-Morley experiment, which showed that the speed of light was constant, wasn't in the early 1900s but rather in 1887:

http://en.wikipedia.org/wiki/Michelson-Morley_experiment

[selfishgene.livejournal.com]

You posted a link to de Grey but you didn't provide any 'teaser' material to stimulate my interest. I had never heard of him before. My LJ friends post a lot of links, I only open about 20% of them. Even those I do open, I need at least some information to justify it. Unfortunately a lot of them are weird videos that take x time to download and watch and are only x/2 worthwhile.
But de Grey is very interesting now that I'm familiar with his ideas.