PBS Space Time

Solar activity is still increasing in a sunspot cycle that is proving way more intense than scientists predicted. Just how much stronger is it going to get?

So you’ve decided to jump into a black hole. Good news: as long as the black hole is big enough you can sail through the event horizon without harm.

Cern's Large Hadron Collider routinely collides particles at energies equivalent to a fraction of a second after the Big Bang, but a particle with the energy of an LHC collision hits every square kilometer of the Earth every single second. And we only relatively recently figured out where these cosmic rays are coming from.

Black holes clash in multiple ways with quantum mechanics. One such clash is the black hole information paradox—and a proposed solution—black hole complementarity—may forced us to radically rethink what it even means to say that something to exists.

In the far future we may have advanced propulsion technologies, but what if those technologies never materialize? Are we imprisoned by the vastness of space—doomed to remain in the solar system of our origin? Perhaps not. A possible path to a contemporary cosmic dream may just be to build a ship which can support human life for several generations; a so-called generation ship.

Today we are jumping into a black hole. Again. Why? Well, to determine the fundamental structure of spacetime and its connection to quantum entanglement of course.

The Moon has been one of the most important theoretical stepping stones to our understanding of the universe. We’ve long understood that it could also be our literal stepping stone: humanity’s first destination beyond our atmosphere.

Of all the astronomical phenomena you can witness, the total solar eclipse has to be the most visceral--the most in-your-face reminder that our reality consists of giant balls of rock spinning around stars. It's also the eclipse and phenomena like it that set us on the path to understanding that reality in the first place.

Gravity might not be a more fundamental than the force of a stretched elastic band. Maybe gravity is just an entropic byproduct—an emergent effect of the universe’s tendency to disorder. If you allow entropy to keep you in your seat for a bit, I’ll tell you all about it.

Space seems fundamental. Many physicists now think that the fabric of space emerges from something deeper. And the most existentially disturbing such proposal is that our 3-D universe is just the inward projection of an infinitely distant boundary. A hologram, or sorts. Let’s see how that can actually work, and what the holographic principle really says about the “realness” of this universe.

In 1974 we sent the Arecibo radio message towards Messier 13. The message was mostly symbolic; we weren’t really expecting a reply. Yet surely other civilisations out there are doing the same thing. So, why haven’t we heard anything? What if the silence from the stars is a hint that we shouldn’t be so outgoing? What if aliens are deliberately keeping quiet for fear that they might be destroyed?

EMPs aren’t science fiction. Real militaries are experimenting on real EMP generators, and as Starfish Prime showed us, space nukes can send powerful EMPs to the surface. So what exactly is an EMP, and how dangerous are they?