How To Take Apart Fukushima's 3 Melted-Down Reactors
If the final price comes anywhere near as low as $15 billion (adjusted for inflation) I'll be very, very surprised.
On the subject of robots ...
Personally, I'm waiting to have a combination utility fog / bush robot mapped onto my consciousness.
How an Astronaut Falling Into a Black Hole Would Die Part 2
I'm going to assume some things that are pretty well accepted by the physics community. Of course, one can always find people with opposing viewpoints.
I attended a talk on the firewall issue by Leonard Susskind last week, and he started with some interesting comments on the whole "what do theoretical physicists do?" question.
He gave four cases:
- "Discovery" where someone makes an observation and then the theorists have to figure it out. There are plenty of these. Atomic spectra comes to mind.
- The theorists come up with something, tell the experimentalists about it, and they go off and their observations either do or don't support the theory. A lot of this happens in particle physics.
- A set of theories suggest an underlying common theory, and the theorist seeks a resolution using mathematical elegance as a guide. Susskind's example was Dirac putting together special relativity and quantum mechanics to come up with the relativistic wave equation. He wasn't even specifically talking about electrons, but when applied to electrons, antimatter popped out.
- A set of theories present a glaring conceptual conflict, and concerned theorists seek to resolve the situation. Susskind's example of this was Boltzmann taking on the conflict between Newtonian mechanics with its time-reversibility, and thermodynamics, which is irreversible.
The conflict with firewalls is that quantum entanglement (which has held up very well so far) shouldn't cause the equivalence principal to be violated (this, too, has done very well experimentally). The equivalence principal states that an accelerated observer, absent other information, can't tell if their in a rocket or standing on a surface in a gravitational field. Implied by this is the "no drama" notion that says that nothing interesting should happen when one falls through an event horizon, which itself is a smooth bit of space-time. (I'm assuming here, for the sake of a macroscopic observer, that it's a big enough black hole that tides don't come into play until well towards the central singularity and that the surroundings aren't full of super heated, radiating matter.) The firewall hypothesis arises as a possible solution to what happens (very) late in the evolution of a black hole when most of the matter still inside the horizon is entangled with matter that's been emitted as Hawking radiation. The equivalence principal says that a firewall, being very dramatic, shouldn't happen. This firewall isn't the same as the very, very late stage of a black hole when the Hawking radiation is so intense that nothing is likely to get past and make its way into the hole. Maldacena and Susskind seek to resolve this and have come up with the notion that EPR bridges (entanglement) and wormholes (general relativity) are the same thing. (Now before everyone gets going about wormholes, these aren't expected to be anything more than a sort of identity mapping between entangled particles.) I don't claim to follow everything about how the initial entanglement described in the paper actually comes about, but the overall argument has a feeling of making sense, and a room full of gray haired physicists didn't tear it down. Susskind also pointed out that if black hole horizons become messy, so do other kinds of horizon such as cosmological ones, adding further inelegant complications for the theorists.
The paper by Ellis is interesting in that it could just make the whole problem go away along with the information paradox. Ellis's argument, however, assumes that the classical event horizon that goes into the infinite future is the real one. Personally, I like dynamical/apparent horizons better.
Link Rot and the US Supreme Court
srsly, SCOTUS isn't the first place of long term reference to have this problem.
Link Rot and the US Supreme Court
-- member of Project Xanadu
My SSID Is...
I find it interesting that for this audience the media list doesn't include books.
A Cold Look at Cold Fusion Claims: Why E-Cat Looks Like a Hoax
Something that makes this new paper fit in with all previous "scientific" papers I've seen on cold fusion:
- No error analysis. Just straight numbers and tidy graphs with no error bars. The couple of uncertainty ranges added to make it look better were pulled out of their hat.
- Pictures of the experimental apparatus, but no diagrams of what's actually claimed to be going on.
- Most of the authors have never been seen before on arxiv.
- The one who has posted a lot to arxiv (Essen) has mostly produced articles relating to fractured ceramic vessels.
Physicists Create Quantum Link Between Photons That Don't Exist At the Same Time
It looks like quantum teleportation meets delayed choice.
NWS Announces Big Computer Upgrade
It would be nice if they'd also do something about the remote sensing infrastructure to get more data to these nice new supercomputers. My current understanding is that the Feds are getting increasingly weak in that department.
Scientist Seeks 'Adventurous Human Woman' For Neanderthal Baby
This will definitely give the bio-ethicists something to chew on.
Mathematicians Extend Einstein's Special Relativity Beyond Speed of Light
A friend of my in the 70's who was a math grad student at the time was playing with taking the absolute value of gamma = 1 / sqrt(1-v^2/c^2) to avoid the imaginary aspect of the term. Only at light speed was a massive particle forbidden. The square of the momentum remains real. Other results were the same: Things become less energetic the farther you get from light speed in either direction. At sqrt(2) times c, your relativistic mass and time are the same as at rest and your subjective trip time matches that of distant observers. Finally, at infinite speed you have zero mass and your subjective trip time is the same as the distance traveled (times c, of course).
I seriously doubt my friend was the first person to come up with this.
What's different with the new publication, AFAICT, is that these guys have an eager university press office. I love it when the press release folks feel obliged to mention that the work appears in a "prestigious" journal.
Scientists Themselves Play Large Role In Bad Reporting
I've seen many Slashdot posts that are copy/pastes of press releases, so what's new. I follow eurekalert.org, and have been really appalled at times at the low quality of the reporting.
Interviews: Ask Physicist Giovanni Organtini About the Possible Higgs Boson Discovery
I'm curious what's going on such that the top is heavier than the Higgs rather than the other way around. All I've been able to find is people asking why the top was found first. *That* I understand--the Higgs signal is much much smaller. I remember something from long ago about the top's mass "leaking," if you will, to the the lighter particles, but that doesn't mesh with how I understand the Higgs mechanism. Anyway, I would expect the Higgs particle manifestation to be the most massive of those that participate in the Higgs field.
Dark Matter Filament Finally Found
Not so strange. Space.com is one of many more or less hermetically sealed news sites.
Elon Musk Shows off the SpaceX Dragon Space Capsule (Video)
It will be cool if the experimental permit works.
If WikiLeaks Suspect Manning Is Legally Guilty, What Punishment?
I can't decide if the question is about what punishment he should get as opposed to what punishment he's likely to receive. Legally I think they could go for the death penalty. I hope they don't.
Kepler Finds Bizarre Systems
Slashdotting + Ad click revenue => $$$
Visible Light 'X-Ray' Sees Through Solid Objects
The actual "FA" is here, with images. Gigan, et al. say, "opaque materials."
It's Time To Build the Analytical Engine
John Mauchly, who knew a thing or two on the subject, made the same observation in a conversation that touched on the issue. It wasn't so much that Babbage was pushing the day's technology too far, he just never froze his design.