Despite having the world’s knowledge at our fingertips, we live in a time of great scientific illiteracy. Disinformation is rampant about vaccines, climate change and even pandemics like Covid-19. But it gets even trickier when talking about the origins of life, the universe, and everything. Some of the facts we often hear about the cosmos are so absurd to imagine — they can almost feel like a religious dogma.

Of course, cosmic theories are based on mountains of data, not whimsical guesses. Yet, how do scientists really know a supermassive black hole is at the center of the Milky Way? How do scientists know distant nebulae are (sometimes) made of hydrogen clouds? How do scientists know 14 billion years ago there was a massive explosion of matter and energy that formed everything in our universe?

We hear these claims often, but most of us aren’t able to examine the gritty details behind a scientific theory. Two astronomers get at this problem in the new book The Cosmic Revolutionary’s Handbook: Or, How To Beat The Big Bang (Cambridge University Press, 2020).

Written by Luke Barnes, a cosmologist at Western Sydney University and Geraint Lewis, a cosmologist at the University of Sydney, the book lays out much of the raw data we’ve collected about the universe — the brightness of stars in the night sky, the chemical makeup of the cosmos, the drifting of galaxies — and builds up the ways scientists come to the conclusions we’re familiar with.

But Handbook goes one step further, explaining the scientific process in detail, so if you don’t accept the mainstream Big Bang theory, you can create your own. Yes, Barnes and Lewis encourage you to take on the intellectual giants of cosmology — Einstein, Hawking, and all the rest — by taking this data and interpreting your own hypothesis.

But it won’t be easy. There's a good reason theories like the Big Bang have staying power. You can’t cherry pick details either — you’ll need to explain all the data, from galactic redshift to dark matter, and present it all in a demonstrable formula that other physicists can explore. If you succeed, you’ll likely change humanity’s understanding of the cosmos forever. Even if you don’t, by reading this book, you’ll certainly learn a lot about what scientists know — and what they don’t — about the universe.

Supercluster spoke to authors Barnes and Lewis via video chat. This interview has been edited for clarity and length.

Of course, don't expect to find all the answers to any particular topic in just one book. There's just so much knowledge and information, the notion that you need to go beyond is important.

The book is ostensibly aimed at them to say, ‘Alright look, let us give you some advice on why what you're doing isn't working and how you can actually do it better.’ But then we found that there's a whole lot of people who are really interested in seeing behind the scenes of science, to see why cosmologists do the things they do. You know, what is the actual evidence that leads us towards this seemingly slightly weird idea of a Big Bang.

Along the way we do a pretty nice tour of the universe overall. We present it in an interesting, and most importantly, a very raw and unprocessed way, trying to get as down to the facts as much as we can.

So one of the ideas for this book was to draw a line, which we hadn't seen drawn clearly enough, of here's the stuff we see about the universe, and then here's the way we interpret it in the Big Bang Theory. You can't throw away that first bit. The stuff we see in the universe, if you throw that away, you're a conspiracy theorist that thinks NASA is faking photographs and all that sort of stuff. So if you're not a conspiracy nut, that's the stuff you’ve got to deal with. We can measure the Cosmic Microwave Background, but if you can explain it better than the Big Bang can, then you're onto something. Here's how you can do it rather than [come up with] some wacky ideas and see if it's as wacky as our idea. That's not how you do cosmology.

Lemaître realized that if the universe is expanding, it must have started from a more dense state. There would have been lots of high-energy radiation flying around in the initial moments of the universe, which as the universe has expanded, has cooled down, and should still be there in the background. But like a lot of theoretical predictions, they realized that this radiation would be very low-level and detecting it would be a very difficult thing to do.

The basic fact behind the CMB is we have instruments that can measure light at particular wavelengths and can measure the temperature of light, the sort of average energy per particle. When we point those at the sky we see a very uniform background. Once we isolate that background it has the sort of unmistakable signature of being light that's emitted by matter and radiation coupled together.

So this is a really crucial point actually. In 1905, even before the expansion of the universe was discovered, Max Planck worked out what mix of wavelengths of light you’d expect to see if you had matter and radiation perfectly coupled together at the same temperature. It's called a blackbody spectrum and there's a perfectly precise formula, very well experimentally confirmed, and we found it all over the sky at exactly 2.725 Kelvin. So that's the challenge of the CMB, those are the basic facts. What you do with it next is your theory. Go for it, you’re the cosmic revolutionary, take it on, but that's the basic facts.

But that doesn't mean that other people haven't tried to come up with potential sources for the Cosmic Microwave Background. One of the famous ones comes from Fred Hoyle, who is a famous cosmologist in Britain from the ‘50s, ‘60s, and ‘70s. He was famous for coining the phrase Big Bang. It was a derogatory term because he was trying to dismiss it, because he didn't think that the universe was born in a Big Bang at all.

He had his own idea of the steady state universe, which is expanding but is constantly replenishing itself, so it makes more matter as it expands. It always stays at the same density and always looks the same. And if you don't have a birth of the universe as a hot Big Bang then you have to ask yourself where does this Cosmic Microwave Background come from?

[Hoyle] came up with these various pictures, where he had to fill space with matter, you need material out there, but it had to be a special kind of matter, it had to be metallic material that was aligned with magnetic fields and his solution to why we have this background radiation becomes more and more elaborate and more and more fine-tuned and it never really works.

So people propose potential solutions, but nothing actually does as well as the prediction from the Big Bang model, that we should have this perfect blackbody temperature distribution as laid down by Planck and that should come from a time when matter and radiation were tightly coupled together in the early stages of the universe.

Understanding that no measurement is perfect is an integral part of doing science properly. Your conclusions carry the same uncertainty as your measurements. Error bars and certainty statistics and all the mathematical machinery behind that is an essential part of science.

When we made the figures for the book, we thought it was very important to put uncertainties onto measurement points. It becomes a bit of a rude shock for a lot of people entering science, I think, because they don't see this discussion of uncertainty and statistics when they see science portrayed in the media, but it becomes bread and butter any time you actually want to do some science.