Interstellar Expansion WITHOUT Faster Than Light Travel

May 16, 2024

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PBS Space Time - S2024 - E12

In the far future we may have advanced propulsion technologies like matter-antimatter engines and compact fusion drives that allow humans to travel to other stars on timescales shorter than their own lives. But what if those technologies never materialize? Are we imprisoned by the vastness of space—doomed to remain in the solar system of our origin? Perhaps not. A possible path to a contemporary cosmic dream may just be to build a ship which can support human life for several generations; a so-called generation ship.

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PBS Space Time: Season 2024 - 17 Episode s

2024x1 - Can Cosmic Voids Solve The Crisis in Cosmology?
January 10, 2024
Two of the greatest mysteries in cosmology are the nature of dark energy and the apparent conflict in our measurements of the expansion rate of the early versus the modern universe that even dark energy can’t account for. Could both of these be explained by looking to a part of the universe that we’ve largely ignored so far? Could cosmic voids be driving the universe?
2024x2 - Does Antimatter Create Anti-Gravity?
January 17, 2024
From hoverboards to flying cars to cloud cities, anti-gravity is a staple of science fiction and our dream of a less Earth-bound future. But in the real universe gravity appears to be a purely attractive force. Feels like its main MO is keeping us stuck to the surface of this lonely rock. But maybe if we science hard enough we can remove the fiction from science fiction. For the sake of our flying cars we should at least try. And for many years, physicists have wondered whether a certain well-known exotic material may experience gravitational repulsion from the Earth. That material is antimatter, and physicists at CERN have just completed a very long and very difficult experiment to answer a seemingly simple question: does antimatter fall down, or does it fall up?
2024x3 - Did JWST Solve The Mystery of Supermassive Black Hole Origins?
February 14, 2024
This is what we astronomers call a blob, or a smudge, if you want to get really technical. It may not look like much from here, but what do you expect for something near the literal edge of the observable universe. If you were there when this light was emitted, you’d A. be at the beginning of time, and B. be looking at an entire galaxy containing an enormous black hole at its heart. It’s the most distant black hole we’ve semi-directly detected. That’s cool enough on its own, but as an added bonus this one smudge may have solved the mystery of the origin of the supermassive black holes in our universe.
2024x4 - What if Singularities DO NOT Exist?
February 22, 2024
It's not too often that a giant of physics threatens to overturn an idea held to be self-evident by generations of physicists. Well, that may be the fate of the famous Penrose Singularity Theorem if we're to believe a recent paper by Roy Kerr. Long story short, the terrible singularity at the heart of the black hole may be no more.
2024x5 - EMP Attack: The Real Science of Electromagnetic Pulse
February 29, 2024
EMPs aren’t science fiction. Real militaries are experimenting on real EMP generators, and as Starfish Prime showed us, space nukes can send powerful EMPs to the surface. So what exactly is an EMP, and how dangerous are they?
2024x6 - Dark Forest: Should We NOT Contact Aliens?
March 14, 2024
In 1974 we sent the Arecibo radio message towards Messier 13, a globular cluster near the edge of the Milky Way, made up of a few hundred thousand stars. The message was mostly symbolic; we weren’t really expecting a reply. Yet surely other civilisations out there are doing the same thing. So, why haven’t we heard anything? What if the silence from the stars is a hint that we shouldn’t be so outgoing? What if aliens are deliberately keeping quiet for fear that they might be destroyed?
2024x7 - Does Space Emerge From A Holographic Boundary?
March 21, 2024
Space seems fundamental. To build a universe, surely you need something to build it on or in. Many, maybe most physicists now think that the fabric of space emerges from something deeper. And perhaps the most existentially disturbing such proposal is that our 3-D universe is just the inward projection of an infinitely distant boundary. A hologram, or sorts. Let’s see how that can actually work, and what the holographic principle really says about the “realness” of this universe.
2024x8 - What If Gravity is NOT A Fundamental Force? | Entropic Gravity
March 28, 2024
There are four fundamental forces - the strong and weak nuclear forces, electromagnetism, and gravity. Except maybe gravity is no more fundamental than the force of a stretched elastic band. Maybe gravity is just an entropic byproduct—an emergent effect of the universe’s tendency to disorder. If you allow entropy to keep you in your seat for a bit, I’ll tell you all about it.
2024x9 - How Eclipses Revealed Our Solar System
April 6, 2024
Of all the astronomical phenomena you can witness, the total solar eclipse has to be the most visceral--the most in-your-face reminder that our reality consists of giant balls of rock spinning around stars. It's also the eclipse and phenomena like it that set us on the path to understanding that reality in the first place.
2024x10 - Why Is The World Rushing Back To The Moon?
April 18, 2024
The Moon has been one of the most important theoretical stepping stones to our understanding of the universe. We’ve long understood that it could also be our literal stepping stone: humanity’s first destination beyond our atmosphere.
2024x11 - What Happens If You Jump Into A Black Hole?
May 1, 2024
Meet Alice and Bob, famous explorers of the abstract landscape of theoretical physics. Heroes of the gerdankenexperiment—the thought experiment—whose life mission is to find contradictions in the deepest layers of our theories. Today our intrepid pair are jumping into a black hole. Again. Why? Well, to determine the fundamental structure of spacetime and its connection to quantum entanglement of course.
2024x12 - Interstellar Expansion WITHOUT Faster Than Light Travel
May 16, 2024
In the far future we may have advanced propulsion technologies like matter-antimatter engines and compact fusion drives that allow humans to travel to other stars on timescales shorter than their own lives. But what if those technologies never materialize? Are we imprisoned by the vastness of space—doomed to remain in the solar system of our origin? Perhaps not. A possible path to a contemporary cosmic dream may just be to build a ship which can support human life for several generations; a so-called generation ship.
2024x13 - Can Black Holes Unify General Relativity & Quantum Mechanics?
May 24, 2024
Black holes are inevitable predictions of general relativity—our best theory of space, time and gravity. But they clash in multiple ways with quantum mechanics, our equally successful description of the subatomic world. One such clash is the black hole information paradox—and a proposed solution—black hole complementarity—may forced us to radically rethink what it even means to say that something to exists.
2024x14 - How Supernovas Act as Universe’s Largest Particle Accelerators
May 30, 2024
Cern's Large Hadron Collider routinely collides particles at energies equivalent to a fraction of a second after the Big Bang. If this worries you, then the following fact will either put you at ease or scare the hell out of you. And that's that a particle with the energy of an LHC collision hits every square kilometer of the Earth every single second. And we only relatively recently figured out where these cosmic rays are coming from.
2024x15 - Is It IMPOSSIBLE To Cross The Event Horizon? | Black Hole Firewall Paradox
June 13, 2024
So you’ve decided to jump into a black hole. Good news: as long as the black hole is big enough you can sail through the event horizon without harm and get to experience the interior of the black hole before you’re annihilated by the central singularity. Or so we once thought. These days, quite a few physicists believe that the only way to avoid horrible contradictions in fundamental physics generated by black holes is for all them to be surrounded by screens of extreme energy that prevent anything from ever entering the event horizon. Sounds outlandish? Welcome to black holes. So let’s find out why many of our most brilliant physicists take these black hole firewalls deadly seriously.
2024x16 - Will The Sun’s Magnetic Field Flip This Year?
June 20, 2024
Solar activity is still increasing in a sunspot cycle that is proving way more intense than scientists predicted. Just how much stronger is it going to get?
2024x17 - Can a Particle Be Neither Matter Nor Force?
June 27, 2024
All particles belong to two large groups: fermions like protons and electrons make everything we consider "matter", while bosons like photons and gluons transmit the fundamental forces. And that about covers the universe: matter moving through space and time under the action of forces. But what if we could create particles in between these two possibilities. Physics says these neither matter nor force anyons can exist, and they may have some pretty incredible uses. They’re called anyons.

PBS Space Time: All seasons

S0: Specials
8 Episode s
S1: Season 1
1 Episode
S2015: Season 2015
43 Episode s
S2016: Season 2016
48 Episode s
S2017: Season 2017
45 Episode s
S2018: Season 2018
44 Episode s
S2019: Season 2019
40 Episode s
S2020: Season 2020
41 Episode s
S2021: Season 2021
35 Episode s
S2022: Season 2022
34 Episode s
S2023: Season 2023
33 Episode s
S2024: Season 2024
17 Episode s

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2024x1 - Can Cosmic Voids Solve The Crisis in Cosmology?

2024x2 - Does Antimatter Create Anti-Gravity?

2024x3 - Did JWST Solve The Mystery of Supermassive Black Hole Origins?

2024x4 - What if Singularities DO NOT Exist?

2024x5 - EMP Attack: The Real Science of Electromagnetic Pulse

2024x6 - Dark Forest: Should We NOT Contact Aliens?

2024x7 - Does Space Emerge From A Holographic Boundary?

2024x8 - What If Gravity is NOT A Fundamental Force? | Entropic Gravity

2024x9 - How Eclipses Revealed Our Solar System

2024x10 - Why Is The World Rushing Back To The Moon?

2024x11 - What Happens If You Jump Into A Black Hole?

2024x12 - Interstellar Expansion WITHOUT Faster Than Light Travel

2024x13 - Can Black Holes Unify General Relativity & Quantum Mechanics?

2024x14 - How Supernovas Act as Universe’s Largest Particle Accelerators

2024x15 - Is It IMPOSSIBLE To Cross The Event Horizon? | Black Hole Firewall Paradox

2024x16 - Will The Sun’s Magnetic Field Flip This Year?

2024x17 - Can a Particle Be Neither Matter Nor Force?

S0: Specials

S1: Season 1

S2015: Season 2015

S2016: Season 2016

S2017: Season 2017

S2018: Season 2018

S2019: Season 2019

S2020: Season 2020

S2021: Season 2021

S2022: Season 2022

S2023: Season 2023

S2024: Season 2024