How Vacuum Decay Would Destroy The Universe

**SPEAKER_1** (0:00)
Study and play. Come together on a Windows 11 PC. And for a limited time, college students get the best of both worlds. Get the Unreal College Deal, everything you need to study and play with select Windows 11 PCs. Eligible students get a year of Microsoft 365 Premium, and a year of Xbox Game Pass Ultimate with a custom color Xbox wireless controller. Learn more at windows.com/studentoffer.
While supplies last, ends June 30th, in terms at aka.ms slash College PC.

**SPEAKER_3** (0:39)
You could say that again.

**SPEAKER_4** (0:49)
Now we party. Whoo!

**SPEAKER_3** (0:51)
This is incredible!

**SPEAKER_4** (0:53)
Wow, I am clearing the rest of the day.

**Matt O'Dowd** (1:00)
The universe is going to end, but of all the possible ends of the universe, vacuum decay would have to be the most thorough, because it could totally rewrite the laws of physics. Today I hope to help you understand exactly how terrified you should be.
It seems pretty lucky that the universe is how it is. It's just the right size, it's just the right expansion rate, and has just the right particle properties to allow stars and planets and people to exist. The habitability of our universe is largely defined by the properties of the quantum fields that pervade all space. The quantum fields give rise to the particles that make up all matter and all forces, and if those quantum fields were a bit different, none of the familiar structures from atoms to galaxies would be possible.
In fact, for most possible configurations of the quantum fields, no structures would exist at all.
Fortunately things are the way they are, although don't get too cozy. There's at least one mechanism that could rewrite the laws of physics across the universe. That mechanism is vacuum decay, and some physicists think it's inevitable. First to give you a crude picture, vacuum decay looks like a bubble of annihilation that expands at the speed of light, rewriting the nature of the quantum fields as it passes. To understand whether or not this might happen, we first need to understand the quantum fields that it threatens. For that, let's try an analogy. Think of all space as being sort of springy at every point. As a simplistic example, imagine a rubber ring at each point. If you compress the ring in one direction, it bounces back and begins to oscillate around its equilibrium shape. But each ring is also connected to neighboring rings, so it can transfer its oscillations, causing a wave to propagate through space. And there are other ways for the rings to oscillate. It has different vibrational modes. For example, it could twist back and forth on different axes, or deform in more complex ways. We can think of each quantum field as a set of these modes of oscillation. And each quantum field, each type of oscillation, has a corresponding particle, and that's the oscillation itself. Just like the deformed ring, a quantum field wants to return to its equilibrium position. That position is the field value where the energy is minimized. Physicists like to represent this by plotting the energy in the quantum field versus the field value. It takes more energy to get further away from the minimum, the equilibrium point. Just like it takes more energy if you want to deform the rubber ring. Another nice physical analogy is a ball rolling in a dip. The ball will roll up and down, oscillating around the equilibrium, and the height it reaches depends on how much energy it has. For most quantum fields, the minimum energy is where the field value is zero. For example, for an electromagnetic wave, a photon, the electric and magnetic fields rise and fall between positive and negative values, but the average field value is zero. And after the photon passes, the electromagnetic field goes back to zero. But there's one quantum field that breaks these rules. That's the Higgs field. The minimum energy state of the Higgs field is not where the field strength is zero.
Instead, the Higgs field likes to settle into an equilibrium value where it has a real positive value. This means that the entire universe is filled with this soup of Higgs-iness.
Most elementary particles that have mass gain their mass due to interactions with this ubiquitous field. I go into all the details of the mass-granting power of the Higgs mechanism in a previous video.
For today, all you need to know is that there's this one quantum field that has a minimum energy value where the field strength is non-zero, and this also means that the energy carried by the Higgs field is non-zero even at this minimum.

**SPEAKER_1** (5:00)
Tomorrow morning is knocking.

**SPEAKER_4** (5:02)
Stock your fridge now.