Jeffrey Bennett’s handy resource is probably the best primer on Einsteinian relativity on the market today. Far more lucid than your average physics textbook, Bennett runs through a slew of accessible thought experiments that are easy to commit to memory. While quick to emphasize that each of the ideas discussed has sound mathematical basis, there is almost no math in the book. Its focus is on the conceptual — how relativity works, how it is applied, and what Einstein’s ideas can tell us about the nature of scientific inquiry.

It is often said that the concepts of relativity upend our common sense in ways that make them difficult to grasp. But as Bennett points out, this might not be the best way to think about it. Our local experience of spacetime does not include traveling at speeds approaching the speed of light, orbiting in the vicinity of black holes, or compressing objects to infinite densities. How can we have “common” sense about things we don’t commonly experience, Bennett asks? Instead, Einstein’s ideas ask that we revise our everyday intuitions about spacetime in the same way that learning the Earth isn’t flat occasioned us to revisit our intuitions about the meaning of ‘up’ and ‘down’.

Bennett shows readers how, armed with just two foundational principles — that physical laws (or patterns) are the same for everyone (what Hume called the “Principle of Uniformity of Nature”) and that the speed of light is a universal constant — Einstein forever changed our understanding of the universe. Those principles ultimately fused the concepts of space and time such that we can no longer speak of certain phenomena in Newtonian terms, of spooky “action at a distance” between objects orbiting other objects. Einstein resolved this dilemma in 1916 by giving us a new view of gravity, otherwise known as the general theory of relativity. As Bennett writes:
 

“Gravity arises from the curvature of spacetime, and the curvature of spacetime is shaped by the masses within it. The greater the mass, the more it curves spacetime around it. A small object orbiting a more massive object simply follows the straightest possible path that it can given the local structure of spacetime.” (p. 112)

 
There is nothing here that should make your head hurt, excepting perhaps any futile attempts to grapple with the interminable distance between the stars and what that means for our getting there. Early in the book he lays bare this reality while pondering the preposterous speeds at which light travels in a vacuum:
 

“The fastest spacecraft we’ve ever built are traveling out into space at speeds of around 50,000 kilometers per hour, which is the same as about 14 kilometers per second. This is quite fast by human standards; in fact, it is about 100 times as fast as a “speeding bullet.” However, it is less than 1/20,000 of the speed of light, which means that at this speed, it would take more than 20,000 years to go the distance that light travels in a single year.” (pp. 9-10)

 
Consider that Andromeda is our closest neighboring galaxy. It is 2.5 million light-years from Earth. Yeah. The math on that is not pretty for aspiring spacefarers.

Throughout the book Bennett patiently debunks the ‘just a theory’ rhetoric often applied to not just Einstein’s ideas but to various other cornerstones of the sciences. More than anything else, what sets science apart is its evidence-based approach to explaining the natural order of the universe. The corroboration of theories by way of experimentally verifiable predictions affords us deeper insight into the workings of physical reality.

Far more than a ‘theory’ in any colloquial sense, the relativistic effects described by Einstein’s equations have been multiply attested using everything from particle accelerators and nuclear power to mobile phones and GPS navigation and other common-use technologies. What began as fanciful speculation in the young Einstein’s brain became the empirical bedrock of modern physics through repeated testing and validation. We cannot truly understand the universe without first understanding relativity, and we cannot truly understand the essence of science until we understand its commitment to evidence.

Postscript: Double kudos to Bennett for using the proper terminology: ‘general theory of relativity’, as opposed to the ‘theory of general relativity’, the latter of which is not only a semantic contradiction but commonly found in popular press and even in some introductory texts.

Note: This review is mirrored over at Goodreads and at Amazon.

 
 
As with many other sciences, advances in physics tend to proceed in fits and starts. Banner years come in serial fashion, as one high-profile discovery leads to another, leaving out of date textbooks within their wake, while the more fundamental problems can take ages to resolve. If we freeze the frame in January 2016, some of the latest secrets the universe has revealed to us include the discovery of the Higgs boson particle in 2012 (confirmed on 14 March 2013), CERN’S observation of two new baryon particles which may be key to our understanding of the interactions of quarks, and the rumored confirmation of gravitational wave detections which caught fire just this past week (emphasis on the rumored). Meanwhile, dark matter, thought to make up 85% of the universe’s mass, was first theorized in the 1930s, yet we hardly know more about its properties today than we did back then.

Physics in Minutes, by contrast, is a snapshot of the state of physics circa the tail end of 2013. So the tentative confirmation of the short-lived, massive, and massively unstable Higgs particle is given its due, while the discovery of pentaquarks (a vital prediction of quantum chromodynamics), other instantiations of hitherto unobserved baryonic matter, and LIGO’s potential detection of actual gravitational waves (as opposed to imprints of primordial waves in the CMB vis-à-vis the BICEP2 debacle of 2014) don’t make the cut. On occasion, science moves quickly, but not quickly enough to overturn any of the foundational concepts described in this splendid primer.

As a shortcut to conversational competence, this 400-page cheat sheet of sorts delivers exactly what it promises. Key concepts throughout the various realms of physics—from the macroscopic scales of black holes and the universe writ large down to the subatomic world of nuclei and electrons—are unspooled with the right mix of jargon and everyday wordage. You won’t be giving lectures any time soon, but there’s enough on board to keep you afloat at the next cocktail party.

Perfect for lavatories and coffee tables, Physics in Minutes offers up accessible descriptions of the physical principles which govern the Universe and everything within it. Use it to refresh forgotten knowledge, revise common misconceptions or spark far-ranging conversations about existence. Just add thinking.

Note: This review is mirrored over at Goodreads and at Amazon.

 
 
Quantum Physics (2002) is your one-stop primer on the quantum mechanical world — chock full of lucid explanation and revealing quotes by leading physicists. John Gribbin is among my favorite science writers, whose trade books always serve to illuminate physical realities in ways only a rarefied few can.

This addition to the Essential Science series begins with an introduction to classical mechanics, appropriately setting the stage for the quantum revolution that would follow. Far from a complete picture of reality, Newton’s laws of motion and Maxwell’s equations underpinning electrodynamics were only the beginning. And the quantum world proved almost infinitely more mysterious, disclosing a set of superordinary phenomena on nanoscopic scales that bewildered the likes of Einstein and Schrödinger and Feynman and the best minds of our day.

As Gribbin emphasizes frequently here, whether our brains can grasp the nature of quantum physics or not is irrelevant to its experimental efficacy. The specifics of quantum theory have been borne out in experiment after experiment, from subatomic supercolliders to the hydrogen bonding that holds our DNA together. Feynman’s calculations on QED reached the most precise agreement between theory and observation than any other in the history of science. Gribbin compares this level of precision to getting the distance between New York and LA correct within the width of a human hair (1/127th of an inch or 0.2 mm).

Some of the common applications of quantum theory, often taken for granted today, are also covered, such as laser technology used in CD, Blu-ray, and other optical disc formats and retinal surgery; silicon-based devices such as mobile phones and GPS; nuclear power; and, the next frontier, quantum computing.

Very little preliminary knowledge is required to gain from this book; the basics of atomic and subatomic theory will do. The included glossary and index are nice aids as well.

Quantum Physics (2002) is a wonderfully helpful little book on one of the most impenetrable topics in the world of science. As Feynman himself was fond of saying, you may not fully understand the sphinx that is QM. No one does, of course. But in learning about it, you’ll emerge from that dark alley a little less blind than you were before, and with a greater appreciation of cosmic complexity and its brute capacity for shattering our native intuition.

Note: This review is mirrored over at Goodreads and at Amazon.

 
 
Quantum locking, quantum trapping, quantum levitation, flux pinning. Whatever you designate this phenomenon, prepare to have your mind detonated.

Yesterday a physics team from Tel-Aviv University performed a demonstration with a sapphiric crystal wafer that appears to be floating in the air—that’s right, levitating. Why is this block of matter ostensibly immune to the encompassing force of gravity? Because it is offset by another physical force: magnetic fields. Due to the ultra-thin, ultra-cooled superconductor layer applied to the surface of the crystal wafer, the object takes on a diamagnetic property which counteracts both the track’s magnetic field as well as the gravitational effect. This delicate interplay “locks” the object in position and creates the illusion that the object is levitating.

Or in the words of the presenters: “Suspending a superconducting disc above or below a set of permanent magnets, the magnetic field is locked inside the superconductor; a phenomenon called ‘Quantum Trapping’.”

To replicate this party trick you will first need the right type of film coating; the Tel Aviv team made good use of yttrium barium copper oxide. You then supercool this layer to temperatures approaching the freezing point of liquid nitrogen (63 K; −210 °C; −346 °F). At such frigid temperatures, an equal and opposite magnetic field is generated and gravity is repelled, resulting in  the eye-catching proscenium you see in the video.

Don’t expect hoverboards or pendulous vehicles just yet, however, as we know of no room-temperature superconductors flush with these properties. (Yet, that is.) The superconductor’s repellent properties diminish above a critical temperature threshold. Second, the magnetic surfaces seen in this demonstration are not exactly ubiquitous. The sheer strength of the magnetic fields required to sustain something as large as a car, say, is not presently feasible. Still, such hindrances don’t take away from the brilliance of physics in action.

Further reading:

A Mind-Boggling Demonstration of Quantum Levitation

It’s Okay To Be Smart (Joe Hansen)