I thought about linking this Forbes article on the economic situation simply because it’s interesting. What actually made me link it was the sentence at the end:
And reality tells us that we barely avoided, only a week ago, a total systemic financial meltdown; that the policy actions are now finally more aggressive and systematic, and more appropriate; that it will take a long while for interbank and credit markets to mend; that further important policy actions are needed to avoid the meltdown and an even more severe recession; that central banks, instead of being the lenders of last resort, will be, for now, the lenders of first and only resort; that even if we avoid a meltdown, we will experience a severe U.S., advanced economy and, most likely, global recession, the worst in decades; that we are in the middle of a severe global financial and banking crisis, the worst since the Great Depression; and that the flow of macro, earnings and financial news will significantly surprise (as during the last few weeks) on the downside with significant further risks to financial markets.
One sentence! Beginning with a conjunction! I guess the editors allowed it for the dramatic effect, because you could replace all the semicolons and probably three or more of the commas with periods without generating a sentence fragment.
While we’re linking, I’d like to make sure everyone has a chance to read this great post by Dr. Orzel of our own Uncertain Principles. It’s about teaching the photon concept in modern physics education. Turns out that in fact many of the “classic” demonstrations of the photon’s existence in fact don’t require the photon as an explanation at all. With enough subtlety the semi-classical picture works just fine. So why use photons at all, especially since they’re not “particles” in the usual sense and don’t really even have wavefunctions (though that too is a very subtle point fraught with complications)? Well, we use the concept because it’s right. There are in fact photons and there are experiments which unambiguously demonstrate their existence.
Which is not to say that the photon is something to casually throw around without taking a look and understanding all those issues. Every decent quantum optics text I’ve read spends considerable effort hashing out all those considerations in detail. (This one, for instance, does a particularly good job)
But those considerations aren’t too important at the introductory level, and it’s possible – and a good idea – to use the photon at a very early level. It simplifies a lot of problems, makes intuitive sense, and is correct. What’s not to like?
By the way, I notice in yesterday’s post that many readers were not satisfied with giving a “yes/no” answer to the multiple universes question. Instead many of you objected to the whole idea in the first place. If it’s not observable, what difference can it possibly make? This attitude warms my heart. I am strongly a subscriber to the “shut up and calculate” interpretation of quantum mechanics and I find the conclusion of the physicist quoted by EvolutionBlog to be downright nuts:
When I ask Linde whether physicists will ever be able to prove that the multiverse is real, he has a simple answer. “Nothing else fits the data,” he tells me. “We don’t have any alternative explanation for the dark energy; we don’t have any alternative explanation for the smallness of the mass of the electron; we don’t have any alternative explanation for many properties of particles.
Really? Aside from the extreme sketchiness of the claim that in fact a multiverse requires any of those things, how about this for an explanation: those quantities take those values because the underlying final theory happens to contain those values. Is that actually the case? I have no idea, but if we find a final theory and then have to chose between “It is what it is” and “There’s an infinite number of other universes where other theories hold sway and oh by the way there’s no possibility even in theory of ever checking this idea”, well, I can guess which one Occam is going to pull a Sweeney Todd on.
Well, I’m off to take the classical mechanics exam. Actually at the time this goes online I should be pretty close to done. I hope it goes well!