Niayesh Afshordi (left) is professor in the Department of Physics and Astronomy at the University of Waterloo and associate faculty at the Perimeter Institute for Theoretical Physics in Ontario, Canada. He was a consultant to PBS’s NOVA, and outlets including Scientific American, Science, the Guardian, and the New York Times have featured his work. Phil Halper is a fellow of the Royal Astronomical Society and the creator of the popular YouTube series Before the Big Bang. His astronomy images have been featured in the Washington Post, the BBC, and the Guardian. Their book is Battle of the Big Bang.
Why cosmology?
Cosmology is the study of the universe, its distribution, its fate and origins. As a species we are fascinated by origins, we trace out family trees, treasure photos of the past and religious creation stories are ubiquitous across cultures. But with the dawn of twentieth century, it’s finally been possible to scientifically model the evolution of the cosmos and probe these deep question that we crave answers for. We’ve come a long way in our understanding but there’s still far to go. Surely nothing can be more tantalising than revealing the trigger of the Big Bang.
Why this book?
The Big Bang is where perhaps the biggest gap exists between what the public think and what professional scientists accept. We are told that the Big Bang has proven a beginning of time or that it came from an infinitely dense singularity or even that it came from nothing. But science says none of these things. The Big Bang only says the universe was in a hot dense state some 14 billion years ago. What came before is an open question, one we try to address and explore. We wanted to show what was established about the Big Bang and what remains mysterious. To revel in the wonder of the different possible histories of the universe that cosmologists are imagining but to provide caution against false certainty.
Is a theory that will never be experimentally or observationally verified science at all?
It’s tempting to write a two letter answer to this question: No. However, it’s often the case that things are more complicated than they seem. What is at stake is a tricky philosophical question called the demarcation problem. How do we tell science from non-science? A lot of physicists believe this was solved by Sir Karl Popper who suggested that a theory is scientific if it can be falsified by some imaginable experiment. But many philosophers think this is overly simplistic. Any theory can be saved from falsification by adding an auxiliary hypothesis, how do we know if the auxiliary hypothesis is reasonable or not? If a theory isn't testable now, does that mean it never will be? After all, when Aristarchus suggested the heliocentric model, he couldn't have possibly imagined that it would be tested by a telescope thousands of years later. How do we develop theories so that they are testable if we banish ones that are not yet so? Speculation is part of science, and we should embrace it, but at the same time we must not mistake speculation as fact. Only theories that are thoroughly tested can be admitted into our cathedral of scientific knowledge, but that doesn't mean those that haven’t aren’t legitimate parts of the discourse. Ultimately, science as Feynman put it, is 'imagination in a straight jacket' a straight jacket made of observational data.
What’s next?
For us, writing the book was a wonderful but lengthy process. Perhaps we will do another, but there will certainly be a break. How long that would be might depend on how well The Battle of the Big Bang is received. So, if you want more, post those 5 star reviews!
What’s exciting you at the moment?
There are so many existing new developments in cosmology and fundamental physics it’s hard to know where to start. From the Hubble tension to the possibility that dark energy might not be a constant after all, to new telescopes like Euclid, Roman, Event Horizon, Sphere X and many more. But for us the most exciting thing is the new window to the universe revealed by gravitational wave astronomy. This has the potential to probe black holes, maybe even finding echoes from the abyss, the quantum hearts of these astrophysical monsters. More importantly, the Big Bang may have emitted gravitational waves that future probes could detect and perhaps distinguish between the models we examine, revealing a winner in The Battle of the Big Bang.
Images by University of Waterloo and Monica Halper
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