How Much Of The Universe Can Humanity Ever Witness?
Summary
This episode explores the absolute limits of what we can see in the universe, distinguishing between the current particle horizon and the ultimate cosmological event horizon. It explains how the expanding universe and dark energy create a boundary beyond which no light can ever reach us, despite the observable universe currently spanning 46.5 billion light-years. The discussion details how the Hubble horizon will eventually collapse, trapping us in a local bubble and limiting our future view to a maximum radius of 63 billion light-years.
Topics discussed
Sponsorships and episode introduction
The absolute limit of our future view
Light travel time and the cosmic shells
The Cosmic Microwave Background and expansion
Neutrinos and gravitational waves
Sponsor breaks and the particle horizon
Constructing a spacetime diagram
The past light cone and 45-degree angle
Expansion history and dark energy
Co-moving coordinates and finite horizon
Sponsor breaks and curved light cones
Conformal time and the ultimate limit
The Hubble horizon and recession velocity
Photon's journey against expansion
Sponsor breaks and crossing the horizon
Why we can see beyond the Hubble horizon
The collapsing Hubble horizon
The cosmological event horizon
Final view and redshifted light
Sponsor breaks and escaping the bubble
Brilliant, Uber Eats, and other sponsors
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