PBS Space Time

Quantum physics predicts the universe should’ve collapsed right after the Big Bang, because all particles were immeasurably heavier. Yet it obviously didn’t. Observations confirm this puzzle, and experiments at the Large Hadron Collider still haven’t explained why. At its core is the lightness of the Higgs boson, part of the “hierarchy problem,” which many call physics’ biggest unsolved mystery.

The universe is expanding and that expansion is accelerating under the power of dark energy and eventually all matter and energy will be dispersed over such unthinkable distances that nothing can stop space from blowing up infinitely. Unless of course cosmologists blundered and dark energy doesn't even exist. Then it's back to the drawing board.

Dark matter has eluded us for many decades. Even our most advanced particle colliders and sophisticated underground detectors have come up short. But it may be that we can finally solve this mystery with a much simpler experiment, involving a ray of light, a good clock, and the planet Mars.

What do you get if you take something that’s infinitely massive and combining with something else that’s negative infinitely massive? You get a single electron, at least that’s what it looks like in our most precise way of describing the quantum world.

What does an electron really look like? I mean, if we zoom in all the way. Is it a sizeless speck of charge? Is it a multidimensional vortex of quantum strangeness? Is it the boundary of a tiny universe with universe-electrons of its own? Let’s find out.

The James Webb Space Telescope has found a quasar that simultaneously breaks a century-old theoretical limit and may explain the conundrum of gigantic black holes in the early universe.

Every good nerd knows that E=mc^2. Every great nerd knows that, really, E^2=m^2c^4+p^2c^2 Want to know what that even means? Sure, I’ll tell you, but today I’d like to invite you to an even higher level of nerdom with extra bits to Einstein’s famous equation that will make even the greatest nerds quiver in their … space time merch if they turn out to be real.

We know that the universe is getting bigger. And we know that the speed that the universe is getting bigger is also getting bigger. The standard assumption is that the acceleration rate is itself constant, which will result in ultimate heat death. But a recent survey of primordial sound waves frozen into the way galaxies are sprinkled through the universe reveals that this fate is now in question.

Space is expanding evenly everywhere, but if you rewind that expansion you find that all of space was once compacted in an infinitesimal point of infinite density—the singularity at the beginning of time. The expansion of the universe from this point is called the Big Bang. We like to tell this story because it's the correct conclusion from the description of an expanding universe that followed

If you track the motion of individual stars in the ultra-dense star cluster at the very center of the Milky Way you’ll see that they swing in sharp orbits around some vast but invisible mass—that’s the Sagittarius A* supermassive black hole. These are perilous orbits, and sometimes a star wanders just a little too close to that lurking monster, leading to a tidal disruption event.

If we discover how to connect quantum mechanics with general relativity we’ll pretty much win physics. There are multiple theories that claim to do this, but it’s notoriously difficult to test them. Let’s talk about some ideas for quantum gravity experiments that can be done on a non-galaxy-sized lab bench, and in some cases already have been done.

The holy grail of theoretical physics is to find the long-sought theory of quantum gravity. But what if this theory is as mythical as the grail of legend? What if gravity isn’t weirdly quantum at all, but rather … just a bit messy? Or random? So says the postquantum gravity hypothesis of Jonathan Oppenheim.