What is Supersymmetry?

physicists like to understand everything about the physical universe we've come up with a pretty good theory that does a pretty good job this theory is called the standard model using a handful of particles of matter and a few forces we can explain an awful lot of what we see as we study matter and energy space and time however the standard model is not complete there are questions it doesn't answer and so we continue to try and find better theories as explained even more an idea that is often tried is one that we call supersymmetry and I'm going to tell you what supersymmetry is all about in a single sentence a supersymmetric theory is one in which the equations for force in the equations for matter are identical well you might wonder why this is a good idea it turns out that if the world has this property you can explain many mysteries before we talk explicitly about supersymmetry I need to clear up a common misconception supersymmetry is not a theory it is a principle that a theory might have as I said supersymmetry treats forces and matter on equal footing in any theory with that property is said to be super symmetric let me emphasize that point there are dozens of supersymmetric theories and they're also not different this is a little subtle so let me use the idea of the principle of charity as an analogy there are many ways to be charitable an example of three different kinds of charity might be the approach where one works directly with the poor or rich philanthropist or even my buddy Eddie's latest scam if we found that one was ineffective or even all of them we wouldn't have ruled out the idea of charity just a specific approach similarly even if scientists rule out a particular supersymmetric theory it might be that some other theory that treats matter and forces on equal footing is Right disproving specific super metric supersymmetric theories is possible but to rule out the general principle of supersymmetry itself is actually quite difficult so let's take a look at how supersymmetry shows up in physics we'll start with the idea of symmetry symmetry is a common meaning which can be illustrated by the sphere take a look at it as I rotate it around in every direction no matter how much I twist it the sphere looks the same symmetry means that if I make a change the final result is the same in physics we think in terms of mathematical equations let's take a look at a simple example we see here the equation of 3 plus 4 which we all know equals 7 if we swap the order of the 3 and the 4 and have 4 plus 3 it's still equal 7 we can say that addition is symmetric under swapping the order swap the order and get the same answer that's a form of symmetry in particle physics we use much more complicated equations so let's take a look at the standard model equation shown here this equation governs the behavior of particles called fermions and bosons ok I was just kidding that's too complicated we can understand supersymmetry using only the important features of the standard model equation the basic equation is shown here it has a term for matter and a term for forces in each of them as a different color if we swap Mattern forces but not the colors we see that the new equation doesn't look like the old one this equation is not symmetric under the swapping of force and matter so let's see how to make the equation super symmetric I'll start by tossing out some building blocks now excuse me for a moment while I make the equation super symmetric you see that I've added some terms to the equation specifically a new matter and a new force term let's see what happens when we swap the matter and forces in this case when we make the swap we see the new equation is the same as the original one this is the essence of supersymmetry a super symmetric theory is one that treats matter and forces identically this is the most important takeaway message so is all this just mathematical hocus-pocus well maybe we don't actually know if these new and expanded equations which are unchanged if we swap the matter in for scarying terms describe the universe they may not but what if they do why is it the physicists are so interested in this idea of supersymmetry it's because equations they contain supersymmetry can explain some of the mysteries left by the standard model like explaining why gravity is so much weaker than the other forces why the Higgs boson exists and even provides a possible source of the dark matter that seems to govern mysteries and how galaxies rotate just to name a few I describe these benefits in another video so how will we know is supersymmetry is actually seen in the universe well supersymmetric theories predict a cousin particle for every particle we've ever observed these cousin particles have never been observed which is a good reason to be skeptical of the idea of supersymmetry still the idea is attractive enough to have generated over 10,000 scientific papers and the attention of thousands of physicists the search for these cousin particles is a hot research topic and we scientists anxiously await the outcome of these studies the next couple of years will be very exciting Oh

Channel: Fermilab

Views: 550,542

Rating: 4.8762465 out of 5

Keywords: Fermilab, Physics, Supersymmetry, SUSY, supersymmetric, standard model, particles, matter, energy, space, time, particle, questions, theories, force, mysteries, misconception, principle, charity, symmetry, sphere, math, equation, fermions, bosons, explained, proof, metaphor, example, scientist, science, physicist, don lincoln, universe, cousin, research, ian krass, simple, graphics, mathematics, theory, reason, fun, teaching, learn, educational, funny, higgs boson, higgs, dark matter, weak gravity, discovery, explanation

Id: 0CeLRrBAI60

Length: 5min 44sec (344 seconds)

Published: Tue May 21 2013

Reddit Comments

[u/RaoOfPhysics]

Hat-tip to /u/H4rtland who shared this on /r/Physics a few days ago.

[u/Sir-Francis-Drake]

The anti-particles are dark matter. Boom physics solves.

In all seriousness the future is going to be a very interesting place.