The expanding universe is a complicated place. During inflation the universe expanded faster than light, but that's something that actually happens all the time, it's happening right now. This doesn't violate Einstein's theory of relativity since nothing is moving through space faster than light, it's just that space itself is expanding such that far away objects are receding rapidly from each other. Common sense would dictate that objects moving away from us faster than light should be invisible, but they aren't. This is because light can travel from regions of space which are superluminal relative to us into regions that are subluminal. So our observable universe is bigger than our Hubble sphere - it's limited by the particle horizon, the distance light could travel to us since the beginning of time as we know it.
The expanding universe is a complicated place. During inflation the universe expanded faster than light, but that's something that actually happens all the time, it's happening right now. This doesn't violate Einstein's theory of relativity since nothing is moving through space faster than light, it's just that space itself is expanding such that far away objects are receding rapidly from each other. Common sense would dictate that objects moving away from us faster than light should be invisible, but they aren't. This is because light can travel from regions of space which are superluminal relative to us into regions that are subluminal. So our observable universe is bigger than our Hubble sphere - it's limited by the particle horizon, the distance light could travel to us since the beginning of time as we know it.
2014 • Astronomy
Neutron stars are strange and violent phenomena that defy the laws of physics, and new discoveries reveal that these bizarre nightmares are far more deadly than previously believed, with the power to destroy planets and even other stars.
S7E1 • How the Universe Works • 2019 • Astronomy
A hyperadvanced species makes their home on doomed exoplanet Terra, which orbits an aging star. Now they must colonize another world, using robots.
S1E4 • Alien Worlds • 2020 • Astronomy
Dark matter is the biggest mystery of the cosmos. Scientists know that it has been vital to the universe since its birth, and new discoveries reveal that it could create black holes, cause mass extinctions, and might even shape life on Earth itself.
S5E8 • How the Universe Works • 2017 • Astronomy
In summer 1969, Apollo 11 succeeded as the first manned mission to land on the moon. The next challenge was to design and build the first exploration vehicle. It had to allow astronauts to explore the moon's surface, but it had to fit in just a meter square space!
15 • Cosmic Front • 2014 • Astronomy
Orbits are the dynamics that drive the universe. From the smallest asteroid to the largest super-cluster, everything in the universe is in orbit. We owe our very existence to the stability of earth's orbit — it gave us life and keeps us safe. But we are the freaks. Everywhere else we look we find orbits are chaotic, unstable, and violent. Beyond our solar system we find planets that are blow-torched, stars that eat each other, and black holes that destroy everything in their path. Yet on the very largest scale, orbits are also a creative force. clashing galaxies give birth to new stars and new worlds. on the galactic scale orbits even construct the fabric of the universe itself.
S2E5 • How the Universe Works • 2012 • Astronomy
Join Phil for a tour of our capital-M Moon, from surface features, inside to the core, and back in time to theories about its formation.
12 • Crash Course Astronomy • Astronomy