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
Secrets of the Cosmic Microwave Background
Hook up an old antenna to your TV and scan between channels. The static buzz you hear is mostly due to the ambient radio produced by our noisy pre-galactic civilization. But around one percent of that buzz is something very different –...
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
The Crisis in Cosmology
The search for a single number: the hubble constant, which is the rate of expansion of our universe, has consumed astronomers for generations. Finally, two powerful and independent methods have refined its measurement to unprecedented...
PBS
The Strange Universe of Gravitational Lensing
Niels Bohr, a Danish Physicist said “Everything we call real is made of things that cannot be regarded .” Is what we see perceived to be real or is it an illusion? In the world of our mind’s eye, light travels in a straight line. In...
PBS
Sound Waves from the Beginning of Time
Invisible to the naked eye, our night sky is scattered with the 100s of billions of galaxies the fill the known universe. Like the stars, these galaxies form constellations – hidden patterns that echo the reverberations of matter and...
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
100 Years of Relativity + Challenge Winners!
The results are in - on this weeks episode of Spacetime we reveal the answer to our Asteroid Challenge, as well as our T-shirt winners! Check out who saved the world!
PBS
Are Virtual Particles A New Layer of Reality?
Sometimes our mathematical hacks point to strange new aspects of reality. For example Max Planck used a quantization trick to figure out the spectrum of light emitted by hot objects. The quantization part of his math trick was meant to...
PBS
How To Become an Astrophysicist + Challenge Question!
Do you want to major in Astrophysics? Are you thinking about becoming (or ever just wondered how one becomes) an Astrophysicists? Do you want to know Matt O’Dowd’s origin story? Then buckle up and enjoy the ride and try your astrophysics...
PBS
Should We Build a Dyson Sphere? | Space Time | PBS Digital Studios
The Kepler telescope recently noticed a strange partial eclipse that some have speculated could be a Dyson Sphere. Are Dyson Sphere's possible? Are they practical? What other alternatives to futuristic energy capture do we have to choose...
PBS
Loop Quantum Gravity Explained
The holy grail of physics is to connect our understanding of the tiny scales of atoms and subatomic particles with that of the vast scales of planets, galaxies, and the entire universe. To connect quantum physics with Einstein’s general...
PBS
The Impossibility of Perpetual Motion Machines
Bad ideas come and go in physics. But there’s one bit of nonsense that is perhaps more persistent than all others: the perpetual motion machine. No working perpetual motion machine has ever been experiment verified. All break the laws of...
PBS
Are Dark Matter And Dark Energy The Same?
Astronomers are the worst at naming things. Dark energy AND dark matter? Who can remember which is which. But perhaps one astronomer has just fixed it, with a theory that says perhaps actually they are they same stuff.
PBS
Is Dark Energy Getting Stronger?
The power of Dark Energy may be increasing as the universe ages. Subtle clues are emerging that the accepted model for the nature of dark energy and dark matter may not be all that. We saw the first such clue recently in our recent...
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
Can We Survive the Destruction of the Earth? ft. Neal Stephenson
What do we do to protect ourselves from extinction level events? And what if some of those events are unavoidable? Can we survive adrift in space? Find out in this episode of Space Time.
PBS
Could We Terraform Mars?
We already have the technology to bring humans safely to Mars and set up small settlements - or at least could do within a generation. But those settlements will need to be cocooned - shielded against the deadly cold, intense radiation,...
PBS
Could the Universe End by Tearing Apart Every Atom?
The universe is expanding, and that expansion is accelerating. We don’t know what’s causing that acceleration, but that hasn’t stopped us from giving it a name. We call this unknown influence dark energy. The observed acceleration is,...
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
How Far Beyond Earth Could Humanity Spread?
We humans have always been explorers. The great civilizations that have arisen across the world are owed to our restless ancestors. These days, there’s not much of Earth left to explore. But if we look up, there’s a whole universe out...
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...