Posts Tagged ‘Physics’
What happens when an immovable object encounters an unstoppable force? MinutePhysics explains…
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As we acclimate ourselves to anticlimax, we might send ethereal birthday greetings to Edward Williams Morley; he was born on this date in 1838. A chemist by training, Morley is best remembered for his collaboration with physicist Albert Michelson at (what is now) Case Western Reserve University, where both taught. They attempted to detect the relative motion of matter through the stationary luminiferous aether (“aether wind”– the medium required, scientists then believed, for the transmission of light). On their first attempt, they found nothing; they tried again, with more sensitive equipment, and again found nothing.
The Michelson-Morley Experiment, as it’s now known, has been called both the most famous and the most important failed experiment of all time: because the aether couldn’t be detected, scientists had to contemplate the possibility that it didn’t exist… thus, the Michelson-Morley Experiment kicked off the Second Scientific Revolution– initiating the line of research that eventually led to special relativity (in which a stationary aether concept has no role).
[Here's a candidate for the "experiment with surprising results" that might herald the Third Scientific Revolution...]
On the heels of yesterday’s film recommendation, another… albeit somewhat different: Stanford physics professor, Leonard Susskind, one of the fathers of string theory, articulator of the Holographic Principle, and explainer of the Megaverse, has a gift for making science accessible… a gift that is on display in this lecture, “Demystifying the Higgs Boson“:
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As we say “ahh,” we might spare a thought for Pierre de Fermat; he died on this date in 1665. With Descartes, one of the two great mathematicians of the first half of the Seventeenth Century, Fermat made a wide range of contributions (that advanced, among other fronts, the development of Calculus) and is regarded as the Father of Number Theory. But he is best remembered as the author of Fermat’s Last Theorem.* Fermat had written the theorem, in 1637, in the margin of a copy of Diophantus’ Arithmetica– but went on to say that, while he had a proof, it was too large to fit in the margin. He never got around to committing his proof to writing; so mathematicians started, from the time of his death, to try to derive one. While the the theorem was demonstrated for a small number of cases early on, a complete proof became the “white whale” of math, eluding its pursuers until 1995, when Andrew Wiles finally published a proof.
* the assertion that no three positive integers a, b, and c can satisfy the equation an + bn = cn for any integer value of n greater than two
For years both scientists and science fiction writers have suggested that a sufficiently advanced civilisation could– and thus would– create a simulated universe. And since simulations beget simulations (within simulations, within simulations, etc., etc.), there would ultimately be many more simulated universes than real ones… meaning that it would be more likely than not that any one universe– say, ours– is artificial.
First, some background. The problem with all simulations is that the laws of physics, which appear continuous, have to be superimposed onto a discrete three dimensional lattice which advances in steps of time.
The question that Beane and co ask is whether the lattice spacing imposes any kind of limitation on the physical processes we see in the universe. They examine, in particular, high energy processes, which probe smaller regions of space as they get more energetic
What they find is interesting. They say that the lattice spacing imposes a fundamental limit on the energy that particles can have. That’s because nothing can exist that is smaller than the lattice itself.
So if our cosmos is merely a simulation, there ought to be a cut off in the spectrum of high energy particles.
It turns out there is exactly this kind of cut off in the energy of cosmic ray particles, a limit known as the Greisen–Zatsepin–Kuzmin or GZK cut off.
This cut-off has been well studied and comes about because high energy particles interact with the cosmic microwave background and so lose energy as they travel long distances.
But Beane and co calculate that the lattice spacing imposes some additional features on the spectrum. “The most striking feature…is that the angular distribution of the highest energy components would exhibit cubic symmetry in the rest frame of the lattice, deviating signiﬁcantly from isotropy,” they say.
In other words, the cosmic rays would travel preferentially along the axes of the lattice, so we wouldn’t see them equally in all directions.
That’s a measurement we could do now with current technology. Finding the effect would be equivalent to being able to to ‘see’ the orientation of lattice on which our universe is simulated…
Read the whole mind-blowing story (including some comforting caveats) at “The Measurement That Would Reveal The Universe As A Computer Simulation” (and find Beane’s paper here).
As we wonder if there’s a “reset” button, we might spare a thought for the extraordinary Erwin Rudolf Josef Alexander Schrödinger; he died on this date in 1961. A physicist best remembered in his field for his contributions to the development of quantum mechanics (e.g., the Schrödinger equation), and more generally for his “Schrödinger’s cat“ thought experiment– a critique of the Copenhagen interpretation of quantum mechanics– he also wrote on philosophy and theoretical biology. Indeed, both James Watson, and independently, Francis Crick, co-discoverers of the structure of DNA, credited Schrödinger’s What is Life? (1944), with its theoretical description of how the storage of genetic information might work, as an inspiration.
It seems plain and self-evident, yet it needs to be said: the isolated knowledge obtained by a group of specialists in a narrow field has in itself no value whatsoever, but only in its synthesis with all the rest of knowledge and only inasmuch as it really contributes in this synthesis toward answering the demand, “Who are we?”
- from Science and Humanism, 1951
… to photos…
… readers will find the backstories to these gaffes and myriad others at Poynter’s “The best (and worst) media errors and corrections of 2012.”
Special Bonus: Jim Romenesko’s Headline of the Year: “Maneater: Hall Bitten by Oates.”
As we fixate on fact-checking, we might recall that this is the birthday of quantum physics: it was on this date in 1900 that Max Planck published his study of the effect of radiation on a “blackbody” substance, demonstrating that in certain situations energy exhibits the characteristics of physical matter– something unthinkable at the time– and suggesting that energy exists in discrete packets, which he called “quanta”… thus laying the foundation on which he, Einstein, Bohr, Schrodinger, Dirac, and others built our modern understanding of physics.
As readers know, some physicists believe that the universe as we know it is actually a giant hologram, giving us the illusion of three-dimensions, while in fact all the action is occurring on a two-dimensional boundary region (see here, here, and here)… shadows on the walls of a cave, indeed.
A common theme of science fiction movies and books is the idea that we’re all living in a simulated universe—that nothing is actually real. This is no trivial pursuit: some of the greatest minds in history, from Plato, to Descartes, have pondered the possibility. Though, none were able to offer proof that such an idea is even possible. Now, a team of physicists working at the University of Bonn have come up with a possible means for providing us with the evidence we are looking for; namely, a measurable way to show that our universe is indeed simulated. They have written a paper describing their idea and have uploaded it to the preprint server arXiv…
Phys.Org has the whole story at “Is it real? Physicists propose method to determine if the universe is a simulation“; the paper mentioned above can be downloaded here.
As we reach for the “reset” button, we might send carefully-calculated birthday greetings to Paul Isaac Bernays; he was born on this date in 1888. A close associate of David Hilbert (of “Hilbert’s Hotel” fame), Bernays was one the foremost philosophers of mathematics of the Twentieth Century, who made important contributions to mathematical logic and axiomatic set theory. Bernays is perhaps best remembered for his revision and improvement of the (early, incomplete) set theory advanced by John von Neumann in the 1920s; Bernays’s work, with some subsequent modifications by Kurt Gödel, is now known as the Von Neumann–Bernays–Gödel set theory.
Lest, per the simulation speculation above suggest that cosmology has a hammerlock on weirdness: Set theory is used, among other purposes, to describe the symmetries inherent in families of elementary particles and in crystals. Materials such as a liquid or a gas in equilibrium, made of uniformly distributed particles, exhibit perfect spatial symmetry—they look the same everywhere and in every direction… a condition that “breaks” at very low temperature, when the particles form crystals (which have some symmetry, but less)… Now Nobel Laureate Frank Wilczek has suggested that there may exist “Time Crystals“– whose structure would repeat periodically, as with an ordinary crystal, but in time rather than in space… a kind of “perpetual motion ‘machine’” (weirder yet, one that doesn’t violate the laws of thermodynamics).