Wednesday, December 21, 2005
The classical physics of Newton separates clearly between matter and information. A kid throws a rock in the air; The rock is matter, the coordinates x(t) of this rock are information. Information is information about matter. The air is matter, the field describing the temperature T(x,t) at each point is information. Physics is the science of matter, while mathematics and nowadays computer science handles information.
It all changed 1915 with the theory of General Relativity (GR). The geometry g is needed to measure distances and is thus information about matter. The various types of matter are described by the stress-energy tensor T. Or so you would perhaps think. But then how do we understand the vacuum solutions of GR? There is no matter, so what does the geometry mean? It calculates distances, but distances between what? The 'official' answer is that the geometry of a vacuum solution measures distances between arbitrarily tiny test-particles (because information has to be about matter). But those test particles do not appear in the field equation.
In my opinion, GR indicates clearly that our separation of matter and information is just one of several prejudices, which one needs to give up at some point. The study and discovery of exact solutions in GR may be the Zen-like exercise to find a fresh perspective on this issue. The Schwarzschild solution was the first vacuum solution; It was found in 1916 but it took several decades until it was fully understood to describe the curved space-time of a black hole without any matter.
In my humble opinion, the Copenhagen interpretation and the philosophy of Niels Bohr is still the best approach to understand quantum theory and physics in general. The core idea of this philosophy, as I understand it, is the following: There is one reality, but multiple descriptions of this reality are necessary. These descriptions are incompatibel, but the correspondence principle explains why we do not observe contradicting evidence.
In particular, the measurement of observables requires the classical description of the observer (usually including a measurement device), while quantum mechanics describes the evolution of the objects in a particular experiment.
The classical description is in this case a coarse-grained macroscopic description. This is necessary, since the observer cannot describe or store her own microscopic state. As long as physics requires an observer, the split in two different descriptions cannot be avoided.
The microscopic description is fundamental in the sense that we can (almost) arbitrarily choose objects for our experiments. We can choose objects in a laboratory (e.g. elementary particles), or we can choose a certain region of space-time(e.g. a black hole) and (try to) determine its quantum state.
The classical, macroscopic description is fundamental, because we cannot extend the microscopic description to the whole universe. The observer cannot determine or describe her own quantum state and has to describe herself and her measurement devices using a coarse-grained description, reducing the description to a few variables.
The correspondenc principle indicates when to switch from one description to the other and how to choose the split between both descriptions; A quantitative formulation requires the calculation of decoherence effects.
While the classical description includes spacetime and in particular a time parameter, the quantum theory of gravity may not contain this concept.
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Sunday, December 18, 2005
the price of oil
We demand clean beaches and untouched wildernesses at home but live in an energy-intensive fashion that leads other countries to sacrifice their waters and forests. This disconnect is easily explained. You don't need to alter your lifestyle much to help protect baby seals or punish Kathie Lee for supporting sweatshops, but you might need to suffer inconveniences - like higher gas prices, energy-conservation efforts and new taxes for alternative-fuels research - if better energy policies were adopted. In the end, the only red line that Americans insist upon, in terms of unacceptable ways for gasoline to be supplied to our cars, is that it must not come from ANWR or the waters off California and Florida. The politicians and environmental groups are, in many ways, just following the wishes of voters and donors.
the new world economy
If the protection of our environment comes at the expense of others, might it be an expression of selfishness rather than virtue? The more we focus on defending our environment, the less we may focus on environments outside our borders; activism can become anesthesia. Domestic restrictions on drilling have had the unintended effect of insulating our tender consciences from the worst impacts of oil extraction. Out of sight, out of mind. For that reason, could it be that drilling rigs within sight of Key West or in a part of Alaska that is an Alamo of conservationism would be a useful thing? Perhaps a few more drilling platforms in our most precious lands and waters would make us understand that the true cost of oil is not posted at the gas pump.
The argument over Wal-Mart's virtue or villainy is interesting but ultimately academic; it is like having had an argument, at the dawn of the microchip, about the merits of automation. The service economy is a reality of our time, and it would be wishful to expect that its engine can sustain the middle class in the way that industry once did. Wal-Mart didn't ask to be the new G.M., and even if it wanted to treat its employees as generously, it couldn't; Furman concludes that Wal-Mart's profits would be obliterated by adopting companywide health care or a significant raise in wages. It makes little sense to blame one company for the pain caused by a profound economic transformation.
What would be more constructive, probably, is a total reimagination of the basic contract between government, businesses and workers - a process that Clinton tentatively put in motion but that has since stalled as both parties retreated from the vexing challenges of globalization. After all, if you were going to sit down and create a system for our time, it probably wouldn't look much like the one we have. Does it make sense to expect businesses to finance lavish health care plans when foreign competition is forcing companies to cut their costs? Isn't government better equipped to insure a nomadic work force while employers take on the more manageable task of childcare - a problem that hardly existed 50 years ago? If government were to remove the burden of health care costs from businesses, enabling them to better compete, wouldn't it then be more reasonable to create disincentives for employers who are thinking of shipping their jobs overseas? Isn't the very notion of a payroll tax for workers antiquated and inequitable in a society where so many Americans earn stock dividends and where a growing number are self-employed? If they were to spend more time debating these and other longer-term questions, our politicians might have some small hope of leaving a legacy to match their predecessors' - a legacy better than the choice between the New Deal and no deal at all.
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Saturday, December 17, 2005
on the TV front
TV programming in 2005
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Monday, December 12, 2005
god i'm in love;
like u know when yr in love
when u say totally sappy shite to a girl
and totally mean every word of it :D
god this sux;
i shaved my balls for u!
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