By Rohan Roberts
A fantastic romp along the frontiers of modern cosmology – and beyond. Halpern makes us wonder about our place in the vast universe, both in space and time, and marvel at the mystery of dark matter, dark energy, extra dimensions, parallel universes, and so much more. — Cliff Pickover
In accessible prose and with lucid explanations, Paul Halpern discusses how big the universe is, what it is made of, what lies beyond it, and whether there was time before the Big Bang. Along the way he drops delicious intellectual titbits such as the possibilities of extra dimensions, the nature of dark matter, and the existence of parallel universes. With very effective analogies and cleverly constructed metaphors, Halpern expatiates on that granddaddy of all questions: What lies at the edge of the universe?
Halpern first takes the reader on a journey through space—to the edge of the observable universe and reminds us that we cannot peek beyond the borders of the observable universe, no matter how good our telescopes. The fact is, we don’t know what fraction of the entire universe the visible universe represents. But not to fear, because stretching 93 billion light years across, the observable universe is vast enough to keep us occupied for a long time.
The book reminds the reader that any journey to the edge of the universe must also necessarily be a journey back in time—at least from our humble earth-based vantage point. So a journey to the edge of the universe entails a journey 13.75 billion years back in time. That’s how much time it would have taken light from the most distant stars and galaxies observed through Hubble’s deep field images to reach us.
After discussing the ramifications and consequences of an expanding universe, Halpern touches upon the mystery of why the Universe or ‘the fabric of space’ seems so smooth—in other words, the observable universe is remarkably similar no matter which direction we look. One reason for this is the possibility that very early in its existence, the universe experienced an extraordinarily brief period of ultrarapid growth. Physicists call this period the inflationary era. Recent measurements of geometry of space through the Wilkinson Microwave Anisotropy Probe (WMAP) have established it to be absolutely flat.
Halfway through the book, Halpern discusses the latest findings on the Dark Matter and Dark Energy front. He reminds us that dark matter represents 72% of everything in the universe. Oddly enough, Halpern points out that nothingness itself may be the answer to the riddle of dark energy. Dark energy may be understood to be the energy represented by the vacuum of space, also known as zero-point energy. In a corroboration of Lawrence Krauss’s remarkable book ‘A Universe from Nothing’, Halpern reminds us that even in complete vacuums, particles of matter and anti-matter constantly pop in and out of existence. (This is due to the Heisenberg Uncertainty Principle that informs us that the briefer a particle’s lifetime, the less we know about its energy).
Another mind-expanding concept that Halpern discusses is the possibility of a sort of Darwinian notion to string theory—as was earlier proposed by Physicist Leonard Susskind. The fittest universes (or the universes that have the right string vacuum state) survive long enough for intelligent life to evolve. Less ‘fit’ universe die out. This idea paves the way for the possibility of the existence of a multiverse. Primordial space was a spawning ground for bubble universe each with different initial properties. Those universes with different constants and parameters that didn’t allow it to inflate and expand would not be suitable for life.
Halpern exposes the reader to another reality-shattering notion—the possibility that we might be living in a hologram. This idea is based on the principle the surface exteriors of black holes embody all the information inside a black hole. In other words, everything that happens anywhere within a 3-dimensional volume is linked to data on the surface of that volume. Taken to its extreme conclusion, it implies that the information in our 3-dimensional universe is only the surface representation of a far deeper and mysterious physical reality. If this sounds weird and freaky, the book has a more detailed explanation of why this could be true—in ways we aren’t equipped to understand yet.
Halpern enthrals the reader with many more true tales of with such delicious sounding titles “The Great Void of Eridanus” (a sector in the night sky 1 billion light years across with no radio sources—an incredible immense empty region in space) and “Dark Flow to Reaches Beyond” (an account of an astonishingly vast flow of clusters of galaxies moving along a single direction, unexplained by objects within the observable universe.)
For anyone interested in voracious supermassive black holes, the mystery of gamma ray bursts, the possibility of time travel and life in other universes, this is just the book for you—eminently readable and accessible even to the layperson. And if you are wondering whether the universe will end with a bang, bounce, crunch, rip, stretch or whimper, read the book to find out.