Category: cosmology

Theoretical Reorganization

Mark DavisLeave a comment

Sean Carroll of Caltech takes on the philosophy of science in his paper, Beyond Falsifiability: Normal Science in a Multiverse, as part of a larger conversation on modern theoretical physics and experimental methods. Carroll breaks down the problems of Popper’s falsification criterion and arrives at a more pedestrian Bayesian formulation for how to view science. Theories arise, theories get their priors amplified or deflated, that prior support changes due to—often for Carroll—coherence reasons with other theories and considerations and, in the best case, the posterior support improves with better experimental data.

Continuing with the previous posts’ work on expanding Bayes via AIT considerations, the non-continuous changes to a group of scientific theories that arrive with new theories or data require some better model than just adjusting priors. How exactly does coherence play a part in theory formation? If we treat each theory as a binary string that encodes a Turing machine, then the best theory, inductively, is the shortest machine that accepts the data. But we know that there is no machine that can compute that shortest machine, so there needs to be an algorithm that searches through the state space to try to locate the minimal machine. Meanwhile, the data may be varying and the machine may need to incorporate other machines that help improve the coverage of the original machine or are driven by other factors, as Carroll points out:

We use our taste, lessons from experience, and what we know about the rest of physics to help guide us in hopefully productive directions.

The search algorithm is clearly not just brute force in examining every micro variation in the consequences of changing bits in the machine. Instead, large reusable blocks of subroutines get reparameterized or reused with variation.… Read the rest

Simulator Superputz

Mark DavisLeave a comment

The simulation hypothesis is perhaps a bit more interesting than how to add clusters of neural network nodes to do a simple reference resolution task, but it is also less testable. This is the nature of big questions since they would otherwise have been resolved by now. Nevertheless, some theory and experimental analysis has been undertaken for the question of whether or not we are living in a simulation, all based on an assumption that the strangeness of quantum and relativistic realities might be a result of limited computing power in the grand simulator machine. For instance, in a virtual reality game, only the walls that you, as a player, can see need to be calculated and rendered. The other walls that are out of sight exist only as a virtual map in the computer’s memory or persisted to longer-term storage. Likewise, the behavior of virtual microscopic phenomena need not be calculated insofar as the macroscopic results can be rendered, like the fire patterns in a virtual torch.

So one way of explaining physics conundrums like delayed choice quantum erasers, Bell’s inequality, or ER = EPR might be to claim that these sorts of phenomena are the results of a low-fidelity simulation necessitated by the limits of the simulator computer. I think the likelihood that this is true is low, however, because we can imagine that there exists an infinitely large cosmos that merely includes our universe simulation as a mote within it. Low-fidelity simulation constraints might give experimental guidance, but the results could also be supported by just living with the indeterminacy and non-locality as fundamental features of our universe.

It’s worth considering, however, what we should think about the nature of the simulator given this potentially devious (and poorly coded) little Matrix that we find ourselves trapped in?… Read the rest

Gravity and the Dark Star

Mark DavisLeave a comment

I began at 5 AM from the Broomfield Aloft hotel, strategically situated in a sterile “new urban” office park cum apartment complex along the connecting freeway between Denver and Boulder. The whole weekend was fucked in a way: colleges across Colorado were moving in for a Monday start, half of Texas was here already, and most of Colorado planned to head north to the zone of totality. I split off I-25 around Loveland and had success using US 85 northbound through Cheyenne. Continuing up 85 was the original plan, but that fell apart when 85 came to a crawl in the vast prairie lands of Wyoming. I dodged south and east, then, (dodging will be a continuing theme) and entered Nebraska’s panhandle with middling traffic.

I achieved totality on schedule north of Scottsbluff. And it was spectacular. A few fellow adventurers were hanging out along the outflow lane of an RV dump at a state recreation area. One guy flew his drone around a bit. Maybe he wanted B roll for other purposes. I got out fast, but not fast enough, and dodged my way through lane closures designed to provide access from feeder roads. The Nebraska troopers were great, I should add, always willing to wave to us science and spectacle immigrants. Meanwhile, SiriusXM spewed various Sibelius pieces that had “sun” in their name, while the Grateful Dead channel gave us a half dozen versions of Dark Star, the quintessential jam song for the band that dates to the early, psychedelic era of the band.

Was it worth it? I think so, though one failed dodge that left me in a ten mile bumper-to-bumper crawl in rural Nebraska with a full bladder tested my faith in the stellar predictability of gravity.… Read the rest

Quantum Field Is-Oughts

Mark DavisLeave a comment

teleologySean Carroll’s Oxford lecture on Poetic Naturalism is worth watching (below). In many ways it just reiterates several common themes. First, it reinforces the is-ought barrier between values and observations about the natural world. It does so with particular depth, though, by identifying how coarse-grained theories at different levels of explanation can be equally compatible with quantum field theory. Second, and related, he shows how entropy is an emergent property of atomic theory and the interactions of quantum fields (that we think of as particles much of the time) and, importantly, that we can project the same notion of boundary conditions that result in entropy into the future resulting in a kind of effective teleology. That is, there can be some boundary conditions for the evolution of large-scale particle systems that form into configurations that we can label purposeful or purposeful-like. I still like the term “teleonomy” to describe this alternative notion, but the language largely doesn’t matter except as an educational and distinguishing tool against the semantic embeddings of old scholastic monks.

Finally, the poetry aspect resolves in value theories of the world. Many are compatible with descriptive theories, and our resolution of them is through opinion, reason, communications, and, yes, violence and war. There is no monopoly of policy theories, religious claims, or idealizations that hold sway. Instead we have interests and collective movements, and the above, all working together to define our moral frontiers.

 … Read the rest

Spurting into the Undiscovered Country

Mark DavisLeave a comment

voyager_plaqueThere was glop on the windows of the International Space Station. Outside. It was algae. How? Now that is unclear, but there is a recent tradition of arguing against abiogenesis here on Earth and arguing for ideas like panspermia where biological material keeps raining down on the planet, carried by comets and meteorites, trapped in crystal matrices. And there may be evidence that some of that may have happened, if only in the local system, between Mars and Earth.

Panspermia includes as a subset the idea of Directed Panspermia whereby some alien intelligence for some reason sends biological material out to deliberately seed worlds with living things. Why? Well, maybe it is a biological prerogative or an ethical stance. Maybe they feel compelled to do so because they are in some dystopian sci-fi narrative where their star is dying. One last gasping hope for alien kind!

Directed Panspermia as an explanation for life on Earth only sets back the problem of abiogenesis to other ancient suns and other times, and implicitly posits that some of the great known achievements of life on Earth like multicellular forms are less spectacularly improbable than the initial events of proto-life as we hypothesize it might have been. Still, great minds have spent great mental energy on the topic to the point that elaborate schemes involving solar sails have been proposed so that we may someday engage in Directed Panspermia as needed. I give you:

Mautner, M; Matloff, G. (1979). “Directed panspermia: A technical evaluation of seeding nearby solar systems”. J. British Interplanetary Soc. 32: 419.

So we take solar sails and bioengineered lifeforms in tiny capsules. The solar sails are large and thin. They carry the tiny capsules into stellar formations and slow down due to friction.… Read the rest

A Paradigm of Guessing

Mark DavisLeave a comment

boxesThe most interesting thing I’ve read this week comes from Jurgen Schmidhuber’s paper, Algorithmic Theories of Everything, which should be provocative enough to pique the most jaded of interests. And the quote is from way into the paper:

The first number is 2, the second is 4, the third is 6, the fourth is 8. What is the fifth? The correct answer is “250,” because the nth number is n 5 −5n^4 −15n^3 + 125n^2 −224n+ 120. In certain IQ tests, however, the answer “250” will not yield maximal score, because it does not seem to be the “simplest” answer consistent with the data (compare [73]). And physicists and others favor “simple” explanations of observations.

And this is the beginning and the end of logical positivism. How can we assign truth to inductive judgments without crossing from fact to value, and what should that value system be?… Read the rest

Keep Suspicious and Carry On

Mark DavisLeave a comment

I’ve previously argued that it is unlikely that resource-constrained simulations can achieve adequate levels of fidelity to be sufficient for what we observe around us. This argument was a combination of computational irreducibility and assumptions about the complexity of evolutionary trajectories of living beings. There may also be an argument about the observed contingency of the evolutionary process that is an argument against any kind of “intelligent” organizing principle though not against simulation itself.

Leave it to physicists to envision a test of the Bostrom hypothesis that we are living in a computer simulation. Martin Savage and his colleagues look at Quantum Chromodynamic (QCD) theory and current simulation methods for QCD. They conclude that if we are, in fact, living in a simulation, then we might observe specific inconsistencies that arise from finite computing power for the universe as a whole. Those inconsistencies would be observed in looking at the distribution of cosmic ray energies, specifically. Note that if the distribution is not unusual the universe could either be a simulation (just a sophisticated one) or could be a truly physical one (free running and not on another entity’s computational framework). It is only if the distribution is unusual that it might be a simulation.… Read the rest

The Universe is Smeary Stuff

Mark Davis4 Comments

What should our expectations be regarding scientific theories? That question regularly bobs to the surface for me. When I taught physics in the Peace Corps over twenty years ago I worried over it. And now, with an inquisitive thirteen-year-old curious about the recent results from the pursuit of the Higgs Boson asking me questions, I continue to think that the conceptual shifts requisite for scientific understanding are perhaps as important as the science itself.

You see, none of it makes simple, clean sense. And none of it makes sense precisely because there is no conceptual similarity between our everyday scales of interaction and those of the mega and the micro. They are baffling and complex and not fully understood. We should take great pride in this, as human beings. We should revel in the rise of experimentation and rationality that has led us to this baffling precipice. We should not back away into the gray simplicity that predates what our scientific investigations have brought us to, because they make enough sense that they can be understood with some effort. But the urge is there; relent at the scale, scope, and complexity of the edifice that is required to get even basic traction. It either doesn’t impact me or is inhuman at some level.

But it needn’t be. The Higgs Boson is simply badly explained because it it based on preserving explanatory footholds that relate to everyday physics of cars and bowling balls. Drop that assumption and things get both weirder and simultaneously simpler. The universe appears to be composed of stuff that has a holographic quality to it in the sense that holograms replicate images throughout their structure. Break a piece off of a hologram and you can still see the image in it.… Read the rest

Apache Point Memories

Mark DavisLeave a comment

When I was eight or nine, I traveled with my father up into the rarefied air of the Sacramento Mountains of Southern New Mexico. Getting there was long, hot and complicated. Our VW van pushed up over the mountain passes as thunderheads rolled in from the west, plum and steel-gray, and the sky flashed and shuddered under the monsoonal effects of the late-summer deserts. I avoided touching the metal surfaces of the VW van as my father, a professor of electrical engineering, explained how the lighting, were it to hit the car, would likely melt the tires and travel through the shell of the van and into the ground below.

We were in search of another kind of lightning, however, as we passed through the Border Patrol check-point near White Sands and ascended into the Ponderosa Pines of the high, western mountains. The van chugged along but kept ascending and any limitations it may have had were lost on my youthful mind as the smell of pine needles and the cooler air rolled in through the open windows until we finally slowed to a crunching stop in a gravel lot near a couple of unimpressive shacks. We were above the clouds, with just the tops of the cumulonimbus visible to the south and west.

I knew that I was at a place called Sunspot and that there were telescopes there that were used to look at the sun. It was an act of technological disregard of the countless warnings I had received about looking at the sun as a child, including when my father brought home dense smoked filters from the Naval Observatory in Washington DC when I was four to let us watch a full solar eclipse.… Read the rest