A naive quantum field theory calculation of the vacuum energy density predicts a value roughly 10^120 times larger than the observed dark energy density, exposing a massive unresolved crisis in physics.
Lincoln lays out the 'worst prediction in physics': summing quantum field contributions to vacuum energy yields a number about 10^120 times bigger than what's actually observed for dark energy, signaling something is deeply wrong in current theory. ✦ AI generated
Don Lincoln · Lex Fridman · 2026-05-29 · original ↗
starts at this moment · 135:28
“Can you, can you explain this crisis?”
We can take the quantum field theory, and we can calculate what the density of energy is due to quantum field theory... if you add that all up, then you get a number, and that number is the rather embarrassing 10 to the 120 power times, that's a one with 120 zeros after it, bigger than the measurement of dark energy.
verbatim transcript · starts at 135:28
135:28due to quantum field theory. And basically what you do is you take within a volume the all of the wavelengths, the longer wavelengths, the shorter wavelengths, the shorter wave-- shorter and shorter, and you can add them all up. And each wavelength adds a certain amount of energy, and if you add that all up, then you get a number, and that number is the rather embarrassing 10 to the 120 power times, that's a one with 120 zeros after
136:04it, bigger than the measurement of dark energy. So you go, "Yuck, that is not fun at all." And that is because the equation comes to the highest energy or the smallest wavelength particle that you can imagine to the fourth power, since anything to the fourth power is a big deal. So that's where you get that awful number. Now, if it turns out that there is some new physics that's just about at the energy
136:37scale we can measure using our biggest particle accelerators, remember I told you that that was a factor, the maximum energy scale, Planck scale, is 10 to the 15 times bigger than what we can measure now. So let's say that we don't have to calculate up to the Planck scale because something happens, something changes at the energy that we know right now. Well, then that means we don't have to integrate to Planck scale, we
137:03integrate to 10 to the 15th less of the Planck scale, and this thing is to the fourth power, so 10 to the 15th to the fourth power is 60. So now, even if we say, you know, Don, he's brilliant, he's gonna find something at the LHC tomorrow that's gonna solve all this problem, now we've solved it, it's much better. It's only different by 10 to the 60th power,
137:26which is still pretty bleeding big. So the short answer is there is very clearly something going on, something wrong, very badly wrong in the quantum field theory. You know, we have to have, maybe there's another field that balances out the energy, that cancels it down. And even that, you know, that's not so outrageous. You know, you could imagine that there's another, you know, like we have matter and antimatter, they
- ·QFT predicts vacuum energy density from summing field contributions
- ·Predicted value is ~10^120 times observed dark energy density
- ·Discrepancy signals a deep unresolved crisis in physics
- ·Called physics' most embarrassing theoretical mismatch
- ·Theory vs. observation differ by a factor of 10^120
- ·A '1' followed by 120 zeros — beyond ordinary comparison
- ·No known fix reconciles QFT calculation with measurement