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A View From the Top
Thinking of causation as a "two-way street"—along which the passage of information can be inverted—could have implications for the origin of life.
Classic Article: Black Holes, Paradox Regained
In 2004, Stephen Hawking famously conceded that black holes do not devour all information when they swallow matter—seemingly resolving the "black hole information paradox" that had perplexed physicists for decades. But some argue that the paradox remains open, and we must abandon our simple picture of spacetime to unravel it.
Diving into Thomas Nagel's "Mind and Cosmos" (subtitle: "Why the Materialist Neo-Darwinian Conception of Nature Is Almost Certainly False"), I experienced a vague but mounting sense of apprehension--the type one gets during the wine and cheese at a scientific conference when the person you’re speaking to puts finger quotes around the word "evolution." To be perfectly blunt, I thought I had accidentally bought an anti-science polemic by a creationist.
"I would like to defend the untutored reaction of incredulity to the reductionist Neo-Darwinian account of the origin and evolution of life," Nagel tells us near the outset. "It is prima facie highly implausible that life as we know it is the result of a sequence of physical accidents together with the mechanism of natural selection."
Is it? An evolutionary biologist, at this moment, would interject a salient distinction between terms like "physical accident," as they are commonly misapplied when critiquing natural selection, and the ability of imperfect replicators to conserve those random variations across time that yield selective advantage. I don't share Nagel's view that the latter state of affairs is highly implausible; I find it both illuminating and rather wonderful. But so what? Of what concern are our respective personal intuitions about nature? It is highly implausible that the same yardstick becomes shorter when I throw it than when I hold it in my hand: but there it is.
Aware of the raised eyebrows among his target audience, Nagel adds some caveats. His is just "the opinion of a layman"--here he is too modest: he is an accomplished professor of philosophy at New York University--and his "skepticism is not based on religious belief, or belief in any definite alternative."
Well and good. Those cards played, though, he makes a full frontal assault on "psychophysical reductionism," and the reductionist-materialist worldview in general, which he sees as having become a shibboleth among the sciences; one that clearly is going fail. His critique is nothing if not sweeping: "The aim of this book is to argue that the mind-body problem is not just a local problem, having to do with the relation between mind, brain, and behavior in living animal organisms, but that it invades our understanding of the entire cosmos and its history."
I myself see nothing of value in the “intelligent design” crowd, and a good deal at which to be alarmed (to say nothing of what branch of science may be targeted next). Nagel is more tempered: while not buying I.D., he gives the movement credit for opening the way to a large-scale critique of natural selection, and from there to our current schema for understanding nature as a whole. Consciousness, cognition, value are simply not explicable--I am speaking now from Nagel's perspective--by psychophysical reductionism, and likely never will be; therefore even physical phenomena cannot ultimately be explained so long as such explanations are based on materialist, reductionist principles. No, the Cosmos as a whole shows far more evidence of something else going on . . . Tielhard De Chardin seems to be in the offing here . . . something as yet unknown . . . but something that is headed *somewhere*, as "principles of the growth of order" in nature are, "in [their] logical form, teleological rather than mechanistic."
You heard right: Biology is teleological, indeed nature is teleological, clearly assembling itself toward some grand purpose (setting aside that whole "second law of thermodynamics" thing). This is probably the moment that earned Steven Pinker's description of "Mind and Cosmos" as "the shoddy reasoning of a once-great thinker."
Religious folks of a certain bent, by contrast, may cheer--but prematurely. Nagel, an atheist, is adamant that a God-style answer won’t fit the bill either: "So my speculations about an alternative to physics as a theory of everything do not invoke a transcendent being but tend toward complications to the immanent character of the natural order." (In any event, such a God would be quite unlike the Judeo-Christian version. If anything, Nagel's intuition sounds more like what Gene Rodenberry suspected: that the universe as a whole is gradually growing into a self-consciousness that will, in time, bring itself retroactively into existence.) Rather, Nagel is only intending to lay the groundwork for how a non-materialist future science might be called for in order fully to explain the presence of mind in the order of nature.
Or, if you like, the presence of nature in the order of mind.
Without further ado, I am happy to announce the start of FQXi's 2013 Essay Contest!
Our new topic:
It From Bit or Bit From It?
The past century in fundamental physics has shown a steady progression away from thinking about physics, at its deepest level, as a description of material objects and their interactions, and towards physics as a description of the evolution of information about and in the physical world. Moreover, recent years have shown an explosion of interest at the nexus of physics and information, driven by the "information age" in which we live, and more importantly by developments in quantum information theory and computer science.
We must ask the question, though, is information truly fundamental or not? Can we realize John Wheeler's dream, or is it unattainable? We ask: "It From Bit or Bit From It?"
Possible topics or sub-questions include, but are not limited to:
What IS information? What is its relation to "Reality"?
How does nature (the universe and the things therein) "store" and "process" information?
How does understanding information help us understand physics, and vice-versa?
I couldn't write a better introduction to the contest than FQXi Member George Musser, over at the site of our contest partner Scientific American. As George puts it, "Going to a physics conference these days is like landing in The Village of the old TV series The Prisoner, where all anyone talks about is information." Well, now is the time to break out and join us for the discussion here at FQXi.
You can find out more including official rules and entry information at this link. There, you'll also find links to our previous contest entries, including our previous contest Questioning the Foundations.
Entries are due June 28, 2013. Good luck and good writing.
The big news of the day--actually last night--is that a large meteor has apparently fallen on the city of Chelyabinsk in central Russia. The event caused serious damage and resulted in injuries to between 500-1000 people, with estimates still being tallied. This type of event is rare, but not without precedent: In 1908, an even larger meteor fell near the Tunguska river, also in Russia, and leveled more than 2000 square kilometers of forest. Adding to the intrigue, a near-Earth asteroid named 2012 DA14 is currently being monitored by scientists and has just made a close passage to the Earth today. With its closest approach distance projected to be 27,700 kilometers, and with an estimated diameter of 46 meters, the DA14 asteroid flew closer to the Earth than any large asteroid since scientists began monitoring these objects 15 years ago.
(This dramatic footage was uploaded to Youtube by Russia Today, courtesy of Alexsandr Ivanov.)
Taken together, these three events raise the question of how often our planet should suffer destructive impacts from the skies. Of course, small rocky bodies hit the upper atmosphere on a regular basis, whereas larger bodies, with significant destructive potential, are quite rare. Incoming meteors obey a scaling relationship, where the frequency of impact is almost a perfect power-law function of the size, so that the frequency is proportional to the inverse square of the diameter, D, i.e.,
This law apparently holds over a wide range of sizes, down to the tiny dust particles that hit orbiting satellites and up to the 10 km asteroid that killed our dinosaurs. Note that the impact frequency for 10 km asteroids would be about one event every 100 million years (which is about right). While different sources tend to agree on the power-law behavior of this scaling law, the normalization is uncertain, perhaps by an order of magnitude.
If we ignore all uncertainties, the above scaling relation shows that impacts by asteroids as large as DA14 are expected every 2100 years. Near misses, like today's, are more common, so that the DA14 close passage should perhaps be considered as a 'once a millenium' event.
The Tunguska event has been estimated to have an impact energy of about 10 megatons, comparable to a modern nuclear weapon. If this event was due to an asteroid impact, how large would it have to be? Note that the escape speed from Earth is about 11 km/s and the orbit speed of Earth around the Sun is about 30 km/s; impact speeds are thus expected to be of order 20 km/s. In order to attain 10 megatons of energy, the projected mass of the Tunguska asteroid must be about 2 x 1011 grams. For a density of 5 g/cm3, the corresponding diameter is 43 meters. In other words, the Tunguska asteroid is roughly the same size as the DA14 asteroid. In fact, the Wikipedia page lists the frequency of Tunguska events at one every 300 years.
How about the Chelyabinsk event from earlier today? The reports that I have seen to date do not specify the size of the rock, but we can make a rough estimate: Although the injuries are serious, the blast was not as large as the Tunguska event. If the impact energy were as small as one kiloton, the asteroid size would be about 2 meters; if the impact energy were as large as 100 kilotons, the asteroid size would be nearly 10 meters. Taken at face value, the scaling law predicts that 10 meter bodies should hit the Earth once a century. However, these energy estimates specify the size of the incoming body near the surface of Earth, whereas the scaling law holds for bodies striking the top of the atmosphere. As a result, the initial size must be larger, so that the frequency of impacts would be correspondingly lower.
The bottom line is that both Tunguska and DA14 events should occur only once or twice every millennium, whereas Chelyabinsk events could occur more often, perhaps every 100 years (where these estimates should be considered highly approximate). The smaller asteroids that lead to smaller, but still destructive, Chelyabinsk-like events are both relatively common and hard to detect. Larger asteroids like DA14 can be detected, but remain difficult to stop if they are on a collision course with Earth.
Quantum Biology: Flight and Sniffery By ZEEYA MERALI
Another discussion thread for January’s podcast, this time on quantum biology. This item also deserves a thread of its own because its been in the news quite a bit over the past few weeks.
To recap, in last May’s podcast, I chatted to Luca...
The Quasar Cluster that Kills the Cosmological... By ZEEYA MERALI
[picture]Thanks to John Merryman for suggesting the topic of this post. Earlier this month, a team of astronomers led by Roger G. Clowes at the University of Central Lancashire reported the discovery of the largest structure seen in the universe, a...
Here's a vacation photo from this past summer. It's taken on Mars; I went there, along with thousands of fascinated others, on the vehicle of the Curiosity rover and the vehicle of my imagination. I, for one, have yet to come...
Questioning the Foundations: Countdown and Thanks By BRENDAN FOSTER
This Friday, November 30, we will announce the winners of the 2012 Essay Contest, "Questioning the Foundations". We'd like to start the countdown to the big event now with some thanks and brief closing remarks.
Jiggling Atoms: The Art of Physics By ZEEYA MERALI
[picture]Particle physicists may often feel like their lives are part of a game of chance: A roll of the dice determines whether they will find the data they need to discover the Higgs particle--or whether their accelerator will even run at all....