PBS
Is The Universe Finite?
Every time you walk out the door, light from the Big Bang strikes your face, enters your eyes. This is the cosmic microwave background radiation - the left-over heat-glow from the very early universe. We can’t see this microwave light...
PBS
How Does Gravity Affect Light?
We know that gravity exerts its pull on light, and we have an explanation for why. Actually, we have multiple explanations that all predict the same thing. And at first glance, these explanations seem to describe completely different...
PBS
Black Hole Harmonics
When physicists talk about black holes they’re usually referring to highly theoretical objects – static, unchanging black holes viewed from “infinitely” far away. This makes everything clean and simple enough to attempt the already...
PBS
Zeno's Paradox & The Quantum Zeno Effect
“A moving arrow is at rest.” This is obviously a nonsensical contradiction. But Zeno, a Greek philosopher famous for his metaphysical trolling, devised a paradox whose conclusion is just this. Here’s how it goes: if you look at an arrow...
PBS
How Do We Know What Stars Are Made Of?
Pin-pricks in the celestial sphere, through which shines the light of heaven? Or gods and heroes looking down from their constellations? Or lights kindled above middle earth by Varda Elbereth and brightened with the dew of the trees of...
PBS
How Quantum Entanglement Creates Entropy
Entropy is surely one of the most perplexing concepts in physics. It’s variously described as a measure of a system’s disorder - or as the amount of useful work that you can get from it - or as the information hidden by the system....
PBS
Is ACTION The Most Fundamental Property in Physics?
It’s about time we discussed an obscure concept in physics that may be more fundamental than energy and entropy and perhaps time itself. That’s right - the time has come for Action.
PBS
Gravitational Wave Background Discovered?
It was pretty impressive when LIGO detected gravitational waves from colliding black holes. Well we’ve just taken that to the next level with a galaxy-spanning gravitational wave detector that may have detected a foundational element of...
PBS
Why Is 1/137 One of the Greatest Unsolved Problems In Physics?
The Fine Structure Constant is one the strangest numbers in all of physics. It’s the job of physicists to worry about numbers, but there’s one number that physicists have stressed about more than any other. That number is 0.00729735256 -...
PBS
Does Gravity Require Extra Dimensions?
It’s been 120 years since Henry Cavendish measured the gravitational constant with a pair of lead balls suspended by a wire. The fundamental nature of gravity still eludes our best minds - but those secrets may be revealed by turning...
PBS
How Decoherence Splits The Quantum Multiverse
Why is it that we can see these multiple histories play out on the quantum scale, and why do lose sight of them on our macroscopic scale? Many physicists believe that the answer lies in a process known as quantum decoherence.
PBS
What’s Your Brain’s Role in Creating Space & Time?
Physics is the business of figuring out the structure of the world. So are our brains. But sometimes physics comes to conclusions that are in direct conflict with concepts fundamental to our minds, such as the realness of space and time....
PBS
What Happens During a Quantum Jump?
Since the very beginning of quantum mechanics, a debate has raged about how to interpret its bizarre predictions. And at the heart and origin of that debate is the quantum jump or quantum leap - the seemingly miraculous and instantaneous...
PBS
How to Communicate Across the Quantum Multiverse
In the Many Worlds interpretation of quantum mechanics, the universal wavefunction is the reality, encompassing all possible histories and futures and all exist. But we are only sensitive to a slice of the wavefunction corresponding to...
PBS
How Luminiferous Aether Led to Relativity
As the 19th century came to a close, physicists were feeling pretty satisfied with the state of their science. The great edifice of physical theory seemed complete. A few minor experiments remained to verify everything. Little did those...
PBS
Is Earth's Magnetic Field Reversing?
Earth’s magnetic field protects us from deadly space radiation. What if it were drastically weakened, as a precursor to flipping upside down? I mean, it has before … many, many times.. Spaceship Earth has a literal deflector shield. A...
PBS
What Caused the Big Bang?
Every astronomy textbook tells us that soon after the Big Bang, there was a period of exponentially accelerating expansion called cosmic inflation. In a tiny fraction of a second, inflationary expansion multiplied the size of the...
PBS
How Black Holes Kill Galaxies
Black holes are really only dangerous if you get too close. Ha, who am I kidding. It turns out they may be responsible for ending star formation across the entire universe. When we first realized that black holes could have masses of...
PBS
Electroweak Theory and the Origin of the Fundamental Forces
Our universe seems pretty complicated. We have a weird zoo of elementary particles, which interact through very different fundamental forces. But some extremely subtle clues in nature have led us to believe that the forces of nature were...
PBS
Are Cosmic Strings Cracks in the Universe?
Reality has cracks in it. Universe-spanning filaments of ancient Big Bang energy, formed from topological defects in the quantum fields, aka cosmic strings. They have subatomic thickness but prodigious mass and they lash through space at...
PBS
Did Time Start at the Big Bang?
Our universe started with the big bang. But only for the right definition of “our universe”. And of “started” for that matter. In fact, probably the Big Bang is nothing like what you were taught. A hundred years ago we discovered the...
PBS
Does Time Cause Gravity?
We know that gravity must cause clocks to run slow on the basis of logical consistency. And we know that gravity DOES cause clocks to run slow based on many brilliant experiments. But I never explained WHY or HOW gravity causes the flow...
PBS
What If Dark Matter Is Just Black Holes?
It may be that for every star in the universe there are billions of microscopic black holes streaming through the solar system, the planet, even our bodies every second. Sounds horrible - but hey, at least we’d have explained dark matter.
PBS
Why Quantum Computing Requires Quantum Cryptography
Quantum computing is cool, but you know what would be extra awesome - a quantum internet. In fact if we want the first we’ll need the latter. And the first step to the quantum internet is quantum cryptography.