It’s very important to put things in order, right? Because otherwise, how would you know which is the number 1 most popular song on iTunes, so you can look cool by buying it too? Or how would you know who is Who Weekly’s most beautiful person in the world, so you can work your way down the list, being rejected by each of them in turn? Or how would you know who is New Zealand’s Next Top Model?
Following this lofty tradition, today we’re going to rank the world’s best physicists. And to do that, we’ll use an algorithm devised by Johannes Koelman, the Hammock Physicist. This uses something called the Einstein Index, which was designed to try and identify the next Einstein – someone who may have only written a handful of papers but that have had a big impact in their field.
To calculate the Einstein Index all you do is add up the number of citations for each scientist’s top 3 papers, and that total is their Einstein index. It’s very easy to do using Google Scholar which very helpfully gives you the number of citations for each paper, and even lists them in the correct order. Go on, try it yourself at scholar.google.com.
It’s very simple, but we’ve done the work for you anyway. And it’s quite enlightening, as what it also tells you is which are the hottest topics in physics, generating the most frenzied research activity. So even though it sounds frivolous, it’s really a great way to get an overview of what’s happening.
So click through after the break, as we count down the top 10 physicists in the world today.
10. Igor Klebanov (Einstein index 6,349)
Like many of the physicists on this list, Igor Klebanov is a string theorist, meaning that he studies string theory. String theory, of course, is an attempt to explain all the fundamental forces of the universe by the idea that instead of everything being made of particles, it’s instead made out of tiny, tiny loops of string. And what we see as particles are in fact just particular vibrations of these strings.
This may sound a little silly, but it’s one of the best ideas anyone has come up with for developing a quantum theory of gravity. Because of that – and because it’s so complicated there’s still a lot to figure out – it’s hugely popular. Which is why so many of our top 10 physicists, ranked as they are by the popularity of their research, are string theorists.
For more about Igor Klebanov’s work, see his web page at Princeton University.
9. Steven S. Gubser (Einstein index 7,830)
Professor Gubser is also a string theorist, also working at Princeton University. He mostly works on something called gauge-string duality, or AdS/CFT correspondence. ‘AdS’ stands for Anti-de Sitter, which is space-time bent into a particular shape, and ‘CFT’ is conformal field theory, which is a type of quantum theory that explains the interaction between subatomic particles.
(Don’t worry if this all sounds complicated, because it is. You don’t get into the top 10 by studying easy physics.)
For more on his research, and his mountain climbing, visit Steven Gubser’s homepage.
8. Kenneth G. Wilson (Einstein index 8,882)
The first Nobel Prize winner on our list, Professor Wilson was recognised in 1982 “for his theory for critical phenomena in connection with phase transitions”.
Phase transitions are when matter changes from one state to another, like from solid to liquid, or from magnetised to de-magnetised. They’re second order when they happen all throughout the material when it reaches a specific temperature called a critical point. Examples include superconductors, or heating ferromagnetic material to the point where it loses its magnetism.
To find out more in his own words, read Kenneth Wilson’s Nobel Prize lecture.
7. Stephen Hawking (Einstein index 9,797)
At last, a name we all recognise. Stephen Hawking is best known to the public for his book, A Brief History of Time, which popularised many ideas in theoretical physics and cosmology. But he’s also a genuinely good scientist; perhaps his most famous discovery is that of Hawking radiation, which is emitted from black holes.
Black holes, as the name suggests, used to be considered completely black. This is because their gravity is so strong that not even light can escape. But Stephen Hawking found an exception, thanks to quantum fluctuations that create pairs of particles and anti-particles (their antimatter equivalents) right on the surface of a black hole. One half of each pair falls into the black hole, leaving the other one to escape.
In this way, black holes continually lose energy, and can eventually evaporate. This is remarkable in itself, but even more so for being one of the first times quantum mechanics and general relativity (Einstein’s theory of gravity) were shown to combine.
Naturally, being so famous Stephen Hawking has an official website.
6. Sheldon Glashow (Einstein index 10,076)
Another winner! Sheldon Lee Glashow (pronounced GLASH-oh) shared the 1979 Nobel Prize in Physics with Abdus Salam and Steven Weinberg (no. 2 on our list), for their work in unifying two of the fundamental forces of the universe.
There are (currently) known to be four fundamental forces: gravity, electromagnetism, the weak nuclear force (which causes radioactive decay) and the strong nuclear force (which binds atomic nuclei together). Glashow, Salam and Weinberg successfully showed that electromagnetism and the weak nuclear force are derived from an imaginatively named electroweak force.
This unification of two of the forces has set physicists on the path to trying to unite all the others as well, to create a “theory of everything” – and string theory is an attempt at doing this. Although Sheldon Glashow himself is not convinced, calling string theory “a tumor”.
5. Alexander Markovich Polyakov (Einstein index 10,346)
As the name might suggest, Alexander Polyakov is originally Russian, although now he’s also at Princeton University (the Ivy League also features prominently on this list).
In the 1970s and 80s, Polyakov made some important discoveries about gauge symmetries. I alluded to this earlier: these sort of symmetries are very important in creating quantum field theories, like the electroweak theory mentioned above.
But these days, like so many others Polyakov works on string theory.
4. Lisa Randall (Einstein index 10,566)
You probably won’t be surprised to hear the Professor Randall is also a string theorist. But her specialty is the extra dimensions that string theory predicts.
See, to work properly, string theory requires higher dimensions beyond the 3 space and one time dimension we can see. That may sound crazy, but like so many things, just because we can’t see them doesn’t mean they’re not there. And to her credit, Lisa Randall is also involved in trying to figure out how we could possibly detect these dimensions, using the Large Hadron Collider.
3. Edward Witten (Einstein index 11,334)
The story goes that in 1995 a conference was being held to mark the 10th anniversary of string theory, or at least an important development in string theory. Ed Witten felt that such a special occasion needed a special presentation, so he combined a whole lot of ideas about different types of strings and higher dimensions to make a Theory of Everything. As you do. And he called it M-theory, although what the M stands for was never specified.
Ed Witten is yet to win a Nobel Prize, but in 1990 he was the first physicist to win the Fields Medal, which is often regarded as the equivalent of the Nobel Prize for mathematics.
2. Steven Weinberg (Einstein index 12,154)
Thankfully, not another string theorist! Steven Weinberg shared the 1979 Nobel Prize in Physics with Sheldon Glashow (number 6) and Abdus Salam, for creating electroweak theory.
He’s also written many books about science and the universe, ranging from very detailed textbooks on quantum field theory to his views on religion – you can read about that in his essay, A Designer Universe?
1. Juan Maldacena (Einstein index 12,998)
At last, we come to our number one. Juan Maldacena is Argentinean by birth, only 42 years old, he’s also currently at the Institute for Advanced Study at Princeton University, and… yes, he’s a string theorist!
He’s actually the person who came up with the AdS/CFT correspondence, mentioned earlier, which was a breakthrough in finding a way to understand the way gravity works in string theory, but showing that it corresponds to something we know very well, which is a normal quantum field theory.
To do this, he used something called the holographic principle. In the same way that a hologram has only 2 dimensions but can fully represent a 3 dimensional object, the holographic principle says that you can explain gravity in 3 dimensional space – like the one we live in – using a quantum theory in 2 dimensions.
This is a huge simplification, of course. If you want a better explanation, then I recommend reading about it in Maldacena’s own words in this article from Scientific American.
That concludes our top 10 countdown. What do you think? Did your favourite physicist miss out?
Use the comments below to tell us who you think is the next Einstein!