# Search PBS Space Time

## Results

### 2022-01-12: How To Simulate The Universe With DFT

• 15:14: The minimum velocity it could have on reaching the Earth is the solar system’s escape velocity at Earth’s orbit, or around 42 km/s.
• 15:49: Either way, it’ll still have solar system escape velocity after the passage through the earth and we would never see it again.

### 2020-08-17: How Stars Destroy Each Other

• 11:14: ... star - but if that core is above a certain mass it shrinks so that the escape velocity at its surface is greater than the speed of ...

### 2020-07-20: The Boundary Between Black Holes & Neutron Stars

• 05:34: And much more difficult to escape the neutron star - the escape velocity at the surface is up to half the speed of light.
• 05:42: ... stars are on the verge of being black holes, which by definition have an escape velocity at the event horizon equal to the speed of ...
• 05:51: If only you could cram a little more matter into the neutron star, the escape velocity would increase and it would become a black hole.
• 06:36: So more mass in a neutron star means higher surface gravity means higher escape velocity.

### 2018-12-06: Did Life on Earth Come from Space?

• 00:37: ... kicked to a minimum of eleven point two kilometers per second that's the escape velocity at Earth's surface that requires an acceleration of up to hundreds of ...

### 2017-12-13: The Origin of 'Oumuamua, Our First Interstellar Visitor

• 04:00: Another way to think of this is in terms of escape velocity.
• 04:18: The escape velocity at that closest approach was a little over 80 kilometers per second.
• 05:47: ... star would have been over 100 kilometers per second, higher than the escape velocity at the distance of closest approach to that ...

### 2016-12-21: Have They Seen Us?

• 15:59: Some people complained about my use of the expression "escape velocity greater than the speed of light" at the beginning of the episode.
• 16:17: ... derision it receives in nerd circles, it's accepted to talk about the escape velocity at the surface of the Earth because we're used to Newtonian ...
• 16:43: The reason that people poo-poo the expression "escape velocity" is that it reminds us of a strange coincidence.
• 16:49: ... if you use Newtonian gravity to calculate the distance at which the escape velocity reaches the speed of ...
• 17:06: But the concept of escape velocity at the event horizon is still as meaningful as it is from the surface of the Earth.

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

• 00:29: Black holes, objects with densities so high that there's this region, the event horizon, where the escape velocity reaches the speed of light.

### 2016-04-20: Why the Universe Needs Dark Energy

• 04:56: ... universe with exactly the right density, that's expanding at exactly its escape velocity, one that will slow to a stop over infinite time, should be flat, with ...

### 2016-04-13: Will the Universe Expand Forever?

• 02:45: ... I throw it at 11 kilometers per second, which is the escape velocity on Earth's surface, then, by the time it almost stops moving, it will be ...
• 02:58: Now this escape velocity comes right out of Newton's universal law of gravitation, which itself can be derived from the Einstein equations.
• 03:07: The mathematical step from Newton's gravity to escape velocity comes from thinking about energy.
• 03:36: That minimum kinetic energy tells you the escape velocity.
• 03:40: ... analogy-- and, remember, ignoring dark energy-- the universe also has an escape velocity that lets distant galaxies escape each other's gravitational ...
• 04:05: How do we calculate the escape velocity for the whole universe?
• 06:22: Essentially, that's if the expansion is exactly equal to the escape velocity.

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

• 07:03: ... on the surface of a planet or a star needs a minimum speed called the escape velocity in order to get really far and not turn back as it's pulled by the ...
• 07:15: If a planet's radius equals the Schwarzschild radius of the equivalent-mass black hole, it turns out that the escape velocity is the speed of light.

### 2015-04-08: Could You Fart Your Way to the Moon?

• 02:48: In truth, even starting out from low Earth order, you'd be short of Earth's escape velocity by a factor of about a billion.
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