Book: "The Universe in the Rearview Mirror: How Hidden Symmetries Shape Reality"

Where did the big bang happen? It happened everywhere.*

A trip around big ideas in physics and the cosmological rules (re: the symmetries) that govern our universe, The Universe in the Rearview Mirror: How Hidden Symmetries Shape Reality is an easy read covering some less easy theoretical concepts. Relativity (general and special), sub-atomic particle physics, the directionality of time itself, all are among the topics illustrated by author Dave Goldberg. Goldberg, an astrophysicist by trade and frequently asked physicist on io9.com, skillfully delivers conceptually dense material with levity, in a familiar format well suited for the general scientifically-minded readership, and with an often tongue-in-cheek style much like I imagine he employs when teaching his undergraduates at Drexel University.

Like any good survey of a scientific field, The Universe in the Rearview Mirror** is salted liberally with quotes from historically influential figures. One that Goldberg utilizes in his introduction as a succinct justification of the book’s premise comes from Nobel laureate Phil Anderson:

“It is only slightly overstating the case to say that physics is the study of symmetry.”

And from there each chapter of the book gives a progressively compelling case for why such a statement, characterizing physics as the study of symmetry, is indeed only slightly overstating the case. Building from the more intuitive forms of symmetry (e.g. the symmetry of a [rearview] mirror; CPT symmetry; Lorentz invariance) up through mind-bending internal symmetries, critical at the most fundamental levels of physics, and ultimately on to how the breaking of certain symmetries is the crucial factor to the universe we see around us, The Universe in the Rearview Mirror orders the daunting complexities of modern theoretical physics into elegant underlying symmetries, allowing the rest of us to make some sense of it, even if only a little bit.

Of course the symmetries don’t explain everything. But they aren’t supposed to either. In fact much of the book has author Dave Goldberg pointing out just how wrong we often are when it comes to understanding this material intuitively. The theme of symmetries gives us a model with which to gain a better working understanding of the universe. And yet, in the end what we have is still a model and not the universe. Werner Heisenberg said it best:

“We have to remember that what we observe is not nature herself, but nature exposed to our method of questioning.”

The spinning disc of Antworld

*Why did the Big Bang happen everywhere? Because the universe expands like a stretching rubber sheet, not an explosion.
**While there isn’t a footnote on every page, this book probably does have nearly as many footnotes as it does pages. If you don’t like writing with frequent asides consider yourself warned. References to the bottom of the page aside, the notes themselves are often chuckle-worthy.

What would happen to me if I fell into a Black Hole?

A Black Hole

It’s safe to say you wouldn’t survive the trip, so stay on this side of the Event Horizon if you ever want to be seen again.

Black Holes are massive objects occupying a tiny volume in space. When a super-massive star (many times larger than the Sun) stops sustaining enough nuclear fusion at its core to support its size, its mass may collapse into itself and form a Black Hole, sucking in everything around it. Our Milky Way galaxy spirals around a super-massive Black Hole at its center.

Since nothing can escape from the incredible gravitational pull of a Black Hole (even light itself), scientists can only speculate on what would happen to a person falling into a Black Hole. However, it does seem evident that the crushing gravity would not be kind to your body. Soon after passing the Event Horizon, the point of no return, your body’s atomic structure would be ripped apart. The parts of your body closer to the singularity experience a stronger gravitational pull than the parts of your body further away from the singularity. This “tidal gravity” creates a differential gravitational pull on your body that literally stretches you out as you fall in. Alas, the rack of space-time is unforgiving to even the most pliant mind, and ultimately it’s impossible to keep yourself together.

Interestingly, getting sucked into a Black Hole doesn’t necessarily mean all trace of you is permanently erased. Physicist Stephen Hawking recently theorized that Black Holes emit minute amounts of radiation energy, like quantum information signatures of the stuff pulled in. So-called “Hawking Radiation” retains the information characteristics of the stuff that the Black Hole gobbled up; if a carbon atom gets sucked into the Black Hole, eventually the energy equivalent of a carbon atom will spew back out as Hawking Radiation. The information of the universe is conserved. So, at least in quantum theory, you could be reconstituted bit-by-bit if an outside observer were able to interpret Hawking Radiation and piece you together.

Cosmologist Ted Bunn’s Black Hole FAQ (Frequently Asked Questions) offers many expanded answers: http://cosmology.berkeley.edu/Education/BHfaq.html