With all of that, it can be easy for non-scientists and early-career scientists to confuse prejudice with legitimate scientific objections to new ideas. After all, famous physicists and astronomers of the past often had trouble convincing others of the correctness of their theories, which today we acknowledge as legitimate accomplishments. So, when my fellow physicists and I point out that (say) wormholes probably don’t exist or that a project to build a working warp drive is probably doomed to fail, it can seem that we’re out deliberately to spoil dreams and stifle new ideas. While I know some people do take pleasure in wrecking others’ dreams (I’ve run into more than a few in physics), that’s not what I’m about.
So, I’m going to give you a little advice today on the right road to revolution in physics. I’ll start with some general points, then talk about my own area of expertise — general relativity — and where there might be room for change in that theory.
Theoretical physics is hard work
A theoretical physicist has a large set of challenges in this era. Scientific knowledge is cumulative, which means you have a lot of background to learn before you can hope to attempt anything new. If you want to work in the edges of gravitation theory where stuff like wormholes and warp drives lives, you need to know general relativity at an advanced level, the current thinking about quantum gravity, and (in my opinion at least) the mathematical structure of quantum field theories. This isn’t stuff you can pick up in a few weekends of light reading. If you’re interested in other fields — solving the problem of high-temperature superconductivity or figuring out the quantum measurement problem — you’ll need solid backgrounds in those fields, to know where the problems exist and what others have done before.
Starting from scratch can seem tempting, but that way leads to heartache. But there’s nothing wrong with building on the work of others, either! There’s a reason general relativity and quantum physics are so successful: they contain testable predictions, which have been confirmed by experiment. Any new theory has to take those tests and successes into account, so you need to understand why they work before you can see where change is needed. Additionally, ideas from other areas can sometimes be grafted into the theory, using successes in one field to boost another.
Theoretical physics is hard work — but that’s not a bad thing. You can’t reasonably expect to go to your basement and build a rocket from scratch without learning first about fuels, stabilization, and other topics in rocket engineering. You shouldn’t reasonably expect to discover something fundamentally new in gravitation without understanding established gravity theory first. Standing on the shoulders of giants may leave you cold, to quote musician-physicist Michael Stipe, but you kinda need to do it anyway.
The bad news: expect to fail often
If you build a rocket, you risk death and destruction. Everyone who builds rockets faces those risks, from the amateurs to the big companies. The better you know what you’re doing, the higher your chance of success, but you can never make the chance of failure go away completely.
In theoretical physics, the situation is even worse: most theories will fail. Either they will be mathematically inconsistent within themselves, or they will be at odds with experiments or observations. (The good news is that theories don’t kill, so if you try something and it doesn’t work, nobody gets blown up. You might run into trouble if you build an experiment based on a flawed theory, but that’s another story.) Many of the best theorists in physics came up with more failed ideas than successful ones — and many of their successful theories were actually made to work better by people who came after.
But again, that’s OK. The problems arise if you don’t learn from failure; sometimes failure can teach you something new. Some of the most intriguing ideas in theoretical physics came out of ideas that didn’t work. One famous example is the Kaluza-Klein 5-dimensional theory that attempted to unify gravity and electromagnetism in the 1920s, which though unsuccessful in itself is one of the foundations of string theory. And failures can teach us about why other theories work: Einstein proposed an alternative version of quantum theory that doesn’t work, but that failure has helped us understand quantum entanglement and the limits of naive solutions to the problems of quantum measurement.
That latter example is important to me, because as a wet-behind-the-ears physicist entering graduate school, I was confused about something very important. I didn’t like the Copenhagen interpretation of quantum mechanics. However, I thought the right way to go about fixing that problem was to reject a lot of what makes quantum mechanics successful, pushing me hard toward the crackpot corner. Along the way, I tried attacking the theory on its strongest side, rather than trying to understand why it works.These days, I still dislike the Copenhagen interpretation — as all right-minded people do — but I have long since grown to love quantum physics for its elegance and power.
The gravity of the situation
The researchers and science-fiction aficionados who want to make warp drives and wormholes work run into a similar problem I had when I was a quantum hater. The problem is that there is nothing in our experiments or observations that say either wormholes or warp drives should exist. To make it worse, there are several reasons in general relativity and quantum field theory to doubt the existence of the kind of negative-energy-density fields needed to make both of those concepts work.
By contrast, dark matter and dark energy exist and require explanation, so there could be room for new ideas in both of those areas. Not all of those ideas are created equal, though: claiming that dark matter could have negative energy density and therefore make wormholes contradicts astronomical observations. Just because we don’t know the identity of dark matter doesn’t mean we don’t know anything about it! We know roughly how much of it there is, and can place limits on how much it interacts with other matter and within itself. We also know a lot of things it can’t be, which isn’t a bad thing: it’s not neutrinos (of the ordinary type at least), it’s not brown dwarfs or tiny black holes, it’s not Hostess Dingdongs.
But here’s the deal: wormholes and warp drives are almost certainly ruled out by general relativity. If some new theory gravitational managed to solve the problem of dark energy while still replicating the successes of general relativity, then maybe there could be room for such science fiction awesomeness. It’s a really horrible idea to start working on a new theory by saying “wormholes must exist because they’re so fluffy I could just die”, though: far better for such things to arise naturally.
Einstein came up with general relativity to reconcile gravity with special relativity, which itself explained how to reconcile particle motion with the production of light. We got black holes, gravitational waves, gravitational lensing, and cosmology as happy side effects. Quantum mechanics came about to explain the structure of atoms and the spectra of light they produce, and we got … well, pretty much the entire modern technological world. Any new ideas must similarly be grounded in experiment and observation, but also in an understanding of why earlier successful theories work.
Physics is hard, but it’s worth it — if you don’t solve all the mysteries of the cosmos, you’re still learning something wonderful about the world we inhabit. That’s valuable. Go and learn.
- The particularly infamous examples of this, of course, are cases where women have been passed over for Nobel Prizes in favor of male collaborators working on the same projects. Additionally, along with scientific and philosophical objections to relativity, Einstein faced strong antisemitic sentiment from some prominent colleagues, to the point where the Nobel committee actually refused to award a physics prize one year to avoid giving him one. And these are just a few examples we know about. Scientists can be really sucky people sometimes.
- There is a second type of revolution that is desperately needed: changing the culture of physics to stop valuing white men over everyone else. That’s a fundamentally different sort of revolution, though, and a far harder one than merely discovering new successful theories.
- To make matters worse, understanding these areas requires background in classical field theories (especially electromagnetism) and basic quantum theory.
- Or maybe it is. Stay tuned for my Hostess Dingdong Dark Matter Theory.