PBS_SpaceTime

The laws of physics are the same everywhere in the universe. At least we astrophysicists hope so. After all, it’s hard to unravel the complexities of distant parts of the universe if we don’t know the basic rules. But what if this is wrong? There is a hint of evidence that the fundamental constants that govern our universe may evolve over time, and even from one location to another.

The Kepler mission has determined that terrestrial planets are extremely common, and may orbit most stars in the Milky Way. But these planets are difficult to directly image because they’re dense and small. Our Sun is about ten billion times brighter than Earth. Train a distant telescope on us, and it will be overwhelmed by the Sun’s rays. So how can we find terrestrial planets around stars light

In this video, we discuss the reports about the detection of a pair of supermassive black holes orbiting only one light year apart from each other. Studying the dance of these giants should tell us a ton about how black holes grow.

Lurking in the depths of the mathematics of Einstein’s general relativity is an object even stranger than the mysterious black hole. In fact it’s the black hole’s mirror twin, the white hole. Some even think that these could be the origin of our universe.

In 1990, an experiment conceived by Carl Sagan was performed using using the Galileo spacecraft. The purpose? To detect life on a planet based on measurements by a space probe. The experiment was successful, and abundant life was unequivocally confirmed. That planet? The Earth. Now, a quarter century later, we’re on the verge of conducting that same experiment on a world orbiting another star.

Earth has its share of monster storms, but even our most powerful hurricanes are a breeze compared to the great, planet-sized tempests of the gas giants.

Could it be that all the electrons in the universe are simply one, single electron moving back and forth through time?

Last year LIGO announced the detection of gravitational waves from the merger of two black holes. The science world went a little crazy. Only a few weeks ago a new rumour emerged: that LIGO had, for the first time, spotted gravitational waves from the collision of a pair of neutron stars. If it’s true, some long-standing astrophysical mysteries are about to be unlocked.

Are matter, mass, and time real?

We’ve broken down our preconceived notions about mass and time, now let’s redefine what they really are. Since we know that time is not a universal constant, what is? Matt defines causal order and explains how even though time may look different to multiple observers, it is the one concrete reality that we can all agree on.

On July 4th 2016, the Juno spacecraft entered orbit around the planet Jupiter after leaving earth five years ago. The Juno probe will tell us what lies inside the mysterious gas giant and with this information we’ll better understand the formation of our solar system.

If you study a map of the Cosmic Microwave Background, or CMB, you may notice a large, deep blue splotch on the lower right. This area, creatively named the Cold Spot. Is this feature a statistical fluke, the signature of vast supervoids, or even the imprint of another universe?

Paul Dirac’s insights into the nature of Quantum Mechanics laid the foundation for Quantum Field Theory and predicted the existence of anti-matter. Part 1 in our series on Quantum Field Theory.

Get your eclipse glasses ready because the a total solar eclipse is an astronomical event unlike any other.

General Relativity! Spacetime! And... curved lines? On this week's episode of Spacetime, Gabe talks about what it actually means for a line to be straight so we can better understand what we mean by the idea of "Curved Spacetime". To make it easer he will divide this ground work at three parts: Part one: Geometry, part two: Spacetime, part three: Spacetime + curvature. This is part one of our series on General relativity, so be sure to check it out! Part one is about straight lines and curved spaced, no physics. Gabe gives great explanation about how a curve can be “straight” if tangent vectors stay tangent when parallel- transported along with that curve. Simple, isn’t it? This is great example with an ant confined to the surface of an ordinary sphere with no concept of or an access to the direction off the surface. From the ant’s two dimensional confined prospective, curve one between A and B is straight. The vector tangent to curve one at point A remains tangent all along curve one as we parallel transport it to point B. Once the ant does that over lots of curves joining A and B it finds that the tangent vector will remain tangent only. That segment is called a geodesic and piecewise it’s straight. Topology is global, but geometry and curvature are local. Now what we have learned from Gabe is that in a three dimensional space you can test curvature just by moving a vector parallel to itself around a circle. If you end up with the same vector you started with space is flat, if not, it’s curved.

Every once in a while we add a second onto our days. Similar to the Leap Year, this is known as the Leap Second. But, if the Leap Year already helps us account for the offset from a calendar in days, what exactly does the Leap Second do? Check out this video for the answer!

Last time we talked about what curvature means, looked at geodesics, great circles on spheres, and tried to understand the notion of "straightness". This week on Spacetime, we take a detour into how geometry works in spacetime. Get excited, because this episode is even more mind-bending than the last!

We've been through the first few episodes of our crash course on general relativity, and came out alive! But it's officially "time" for CURVED spacetime. Join Gabe on this week’s episode of PBS Space Time as he discusses Newton and Einstein's dispute over inertial frames of reference. Is Einstein's theory inconsistent? Is gravity even a force??? Check out the episode to find out!

We all know tides have something to do with gravity from the Moon and Sun, but if gravity affects the motion of all objects equally, then how come oceans have large tides while other bodies of water don't? It's because your mental picture of the tides is probably WRONG!

Black holes! From Stephen Hawking to Interstellar, black holes are mammoths in the world of science AND sci-fi. But what exactly IS a black hole? Do events happen inside black holes? Are black holes really a hole? Are black holes really black?!

Lots of people believe the Universe is infinite, but there's a good possibility that might not be the case. Which means that there would be an actual edge of the Universe. What happens at that edge? Is there a restaurant?

With millions of Earth-like planets around sun-like stars in our galaxy alone, why don't we see intelligent alien life? Or any other life for that matter? It gets especially weird when you factor in new scientific revelations that life on Earth occurred crazy fast! So if you want to help us theorize on the real reasons we haven't found alien life, you should check this video of Space Time! Why don’t we see alien civilization? The resolution for it has to be that there is some sort of great filter that either makes intelligent life extremely rare in the first place or that wipes out, essentially, all advanced civilization before they get to the galactic empire stage, whether by a nuclear war, environmental catastrophe, accidentally making a black hole that swallows the planet, et etcetera. But some people believe in that and some people just don’t buy that theory. The other logical explanation is that we know of exactly one instance intelligent life happening, the case of the earth. Multicellular life evolved independently dozen of times. It just took a really long time for those single cells to become complex enough to form large collaborative structure capable of collective reproduction, I.e plants, animals, species capable of making the Kerbal Space Program. So what is the great filter? Maybe it’s just time. If life is common then of the billions of Earth-like planets in the galaxy , only a tiny fraction needed to have a small head start on us in order to have produced the Federation of Planets and Stargates and stuff by now. Well, that explains a lot!

When it comes to dangerous asteroids striking Earth, it's not a matter of if, it's a matter of when. We have begun to track projectiles large enough to destroy our planet, and we are in the clear for the foreseeable future. However, there are countless asteroids large enough to take out an entire city that we cannot see. If you’ve ever watched the movie Armageddon, you know what we are talking about. There is a high probability that sometime in the future we would have to resort to those kinds of actions to save our planet. There is a reason to believe that it hasn’t been the first time an asteroid of large proportions changed the course of history when it fell on the Earth and wreaked havoc on it. The dinosaurs as species were wiped of the face of the Earth by an asteroid that hit the coast of the Yucatan peninsula, triggering a series of changes in the Earth’s climate and biodiversity. The first thing to do when under the threat of an asteroid hitting our only home is trying to locate it sooner rather than later. Efforts have been made to scan as much of the dark sky for flying rocks that are bigger than 500m, so that we are aware of their approach, but it’s still unclear as to where those smaller than 500m are. They are just like a grain of sand in the vastness of space. Other ways of dealing with them include finding a way to change their trajectory, whether by kinetic or gravitational force.

Earth mysteries are a wide range of spiritual, quasi-religious and pseudo-scientific ideas focusing on cultural and religious beliefs about the Earth, generally with regard to particular geographical locations of historical significance. Believers in Earth mysteries generally consider certain locations to be "sacred", or that certain spiritual "energies" may be active at those locations. The term "alternative archaeology" has also been used to describe the study of Earth mystery beliefs. A black hole is a region of space-time exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it. The theory of general relativity predicts that a sufficiently compact mass can deform space-time to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, no locally detectable features appear to be observed. In many ways a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved space-time predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe. Black holes have mystified physicists for decades, but with the help of quantum mechanics, we are beginning to make serious progress in understanding these strange objects. This week on Space Time, Matt dives deeper into the physical process of creating a black hole, and what that can tell us about how black holes behave. Take a look as this video is sure to broaden your horizons!

Quantum Field Theory is generally accepted as an accurate description of the subatomic universe. However until recently this theory had one giant hole in it. The particles it describes had no mass!