What I observe, however, is that most people, including those in the referenced fields, have only the vaguest position on cryonics picked up from pop-culture. If you're lucky, something like "those idiots spend a fortune on con artists who tell them freezing a body means it can be revived after Science develops a cure for whatever killed them."
Common sense positions aren't necessarily wrong: any astrogeologist will agree that the Moon is indeed not made of green cheese.
Anyway, comments by "kalla724", who identifies him/herself as a neuroscientist (I can't verify that, but I have no reason to believe he/she is lying) seem quite detailed, and PZ Myers, an evolutionary biologist specialized in the nervous system, also made a technical comment against cryonics.
The Society for Cryobiology, which was initially sympatetic towards cryonics and included cryonicists as their members, later formally distanced themselves from the practice and even banned cryonicists from being members. Is their position on cryonics just vaguely picked up from pop-culture?
So why aren't more scientists writing detailed debunkings of cryonics? Well, one of the house rules of the scientific community is that the burden of providing evidence lies on who is making the claim. Most scientists will not invest time and effort to debunk every detail of arguments in the form of "you can't prove this doesn't work".
At least not until those who make these claim generate enough noise in the arena of public opinion and start political lobbying. At that point, scientists may feel compelled to debunk as a form of civic duty.
The fact that physicists have not flocked to cryonics providers is not in any sense strong evidence that they possess evidence we don't.
No, but the fact that neurobiologists and cryobiologists haven't flocked to cryonics, and in particular cryobiologists have flocked away from it, implies that according to the best available scientifc understanding of the subject, cryonics is unlikely to work.
Tapping out now.
Bye.
In the past, the Cryonics Institute has had a policy that said that they would not accept anyone who is not a member. This has changed. The policy now is that someone who has full legal authority over your body can sign you up after you die. It costs $36,250 to be frozen if you are not signed up, which is more expensive. They also will not do anything until you have been on dry ice for 2 weeks after they have been contacted, so not being a member is more risky.
This is very important news for anyone who is currently cryocrastinating. It means that you can drastically increase your chances of survival without filling out any forms. All you have to do is tell a loved one you want to be frozen upon death, and that you would like them to take responsibility for making sure this happens. This takes literally 30 seconds. Do it now!
This news might also be a reason to not sign up right away, if you think something better (like radical life extension or uploading) will come along in your lifetime. We should discuss this in the comments.
Edit: The general consensus of this discussion is that this is a really bad reason not to sign up for cryonics.