Search PBS Space Time


2022-07-20: What If We Live in a Superdeterministic Universe?

  • 08:18: Let’s play out the Bell test on something called a space-time diagram - with one dimension of space only on the x axis and time on the y.

2021-02-24: Does Time Cause Gravity?

  • 02:09: We can show this with our old friend the spacetime diagram.

2021-02-10: How Does Gravity Warp the Flow of Time?

  • 07:36: We can see that when we use a spacetime diagram to show how the traveler tracks the passage of time back on Earth.
  • 07:52: Here’s the spacetime diagram for our rotating lab.

2021-01-19: Can We Break the Universe?

  • 04:07: The best way to see this is on a space-time diagram.
  • 04:33: ... the spacetime diagram, the set of simultaneous events for a motionless observer lie on a ...
  • 05:12: ... the spacetime diagram, that’s whenever one of these lines of constant time extending from ...
  • 06:20: But to see why we need a much weirder version of the spacetime diagram.
  • 09:46: Again, the best way to see this is on a spacetime diagram.
  • 11:12: The answer is in our looped spacetime diagram.

2020-06-15: What Happens After the Universe Ends?

  • 04:41: This is a spacetime diagram.

2019-04-03: The Edge of an Infinite Universe

  • 05:40: As a quick review: start with a graph of space versus time – a spacetime diagram – then compactify.

2018-11-07: Why String Theory is Right

  • 03:34: On a spacetime diagram, time versus one dimension of space, this is called its world line.
  • 04:32: When strings move on a spacetime diagram, they trace out sheets or columns.

2018-04-04: The Unruh Effect

  • 01:26: We just need a little special relativity and a space-time diagram.
  • 01:34: A space-time diagram has two axes, time and, well, space, with time on the vertical axis.
  • 02:04: On the space-time diagram, this is a line with a 45-degree angle from the vertical axis.

2017-08-16: Extraterrestrial Superstorms

  • 12:41: To prove this to yourself, try drawing a space-time diagram, time on the y-axis and space on the x-axis.

2017-03-29: How Time Becomes Space Inside a Black Hole

  • 05:19: On our ever popular spacetime diagram, we see a sharp division between the two.

2017-03-22: Superluminal Time Travel + Time Warp Challenge Answer

  • 01:23: We'll do this in flat space, so we need a flat or Minkowski spacetime diagram.
  • 04:43: Let's see what that looks like on the spacetime diagram.

2017-03-08: The Race to a Habitable Exoplanet - Time Warp Challenge

  • 00:51: In that episode, we talked about the spacetime diagram and how it transforms between observers traveling at different speeds.
  • 01:35: ... respect to x and to equal zero as contours, then we can transform the spacetime diagram into a 3D graph, in which causality must always flow ...
  • 03:29: To answer this, you'll need to draw a spacetime diagram showing the world lines of the two ships.
  • 04:43: Submit your answers with full explanations and spacetime diagrams within two weeks of the release of this video to be in the running.

2017-02-15: Telescopes of Tomorrow

  • 11:39: ... wondered about the relationship between the geometry I depicted on the space-time diagram and the geometry that comes from mass and energy-curving ...
  • 11:49: The space-time diagram I showed is for flat or Minkowski space.

2017-02-02: The Geometry of Causality

  • 02:49: To preserve our sanity, we represent this on a spacetime diagram plotting time and only one dimension of space.
  • 03:03: There is no standing still on a spacetime diagram.
  • 04:51: First, we need to draw the spacetime diagram from the perspective of one of the other travelers.
  • 06:27: That comes from insisting that we all see the same speed of light, 45 degrees on the spacetime diagram.
  • 09:40: In fact, the nearest downhill contour defines the forward light cone for anyone anywhere on the spacetime diagram.
  • 10:08: ... spacetime diagram we looked at today was for a flat or Minkowski space, in which faster ...

2016-12-08: What Happens at the Event Horizon?

  • 02:08: It's a special type of space-time diagram designed to clarify the nature of horizons.
  • 02:15: But first, a quick refresher on basic space-time diagrams.
  • 02:30: With the right choice of space and time units, the speed of light becomes a diagonal line on the space-time diagram.
  • 03:01: Let's drop a black hole onto our space-time diagram.
  • 03:48: The problem with the regular space-time diagram is that the path of light and the shape of the light cone changes as space-time becomes warped.
  • 04:10: It transforms the regular space-time diagram to give it two powerful features.
  • 04:48: ... as with a regular space-time diagram, blue verticalish lines represent fixed locations in one dimension of ...

2016-02-17: Planet X Discovered?? + Challenge Winners!

  • 04:11: The best way to illustrate this is with a spacetime diagram.
  • 04:21: So a photon clock that stationary on the spacetime diagram moves straight up.

2015-08-19: Do Events Inside Black Holes Happen?

  • 00:37: ... technical terms like "geodesic" or "flat spacetime" and if I can draw a spacetime diagram or ...

2015-07-29: General Relativity & Curved Spacetime Explained!

  • 01:54: ... think about it, on the flat spacetime diagrams of inertia observers, the world lines of other inertial observers are ...
  • 05:44: On a flat spacetime diagram the world lines of those photons should be parallel and congruent.

2015-07-15: Can You Trust Your Eyes in Spacetime?

  • 01:22: Our principle tool for exploring flat spacetime geometry will be something called a spacetime diagram for representing physical events.
  • 04:34: ... spacetime diagrams are great for visualizing cool phenomena like time dilation, or length ...
  • 04:51: Because here's the thing, the answer is not clear a priori since you can't trust your eyes in spacetime diagrams.
  • 05:19: ... spacetime diagrams preserve the spacetime interval between points with its weird minus ...
  • 07:25: But that interpretation doesn't work on a spacetime diagram.
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