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PBS Space Time
How We Know The Earth Is Ancient
Season 6
Episode 11
In astronomy we talk about billions of years like it’s no big deal. But how can we be sure about timescales so far beyond the capacity for human intuition? Our discovery of what we now call deep time is very recent - as recent as our discovery of the true spatial vastness of our universe. And it came as scientists tried to measure the age of the Earth. What they found was shocking and humbling.
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How is it possible to tell if a space rock will one day collide with the Earth?

15:58
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16:35
What if the Big Bang was just an endless cycle?

19:39
Why are billions suddenly being pumped into fusion startups?

16:36
The universe should've collapsed after the Big Bang, but a light Higgs boson let us exist.

14:30
Maybe dark energy doesn't exist?

18:32
Dark matter has eluded us for many decades but we may be able to discover more now.

15:35
What do you get if you combine something that’s infinitely massive and negative infinitely massive?

13:39
What does an electron really look like?

16:35
Is there a limit to how much energy you can cram into, or pull out of one patch of space?

17:19
I’d like to invite you to an even higher level of nerdom!

11:43
Gravitational tsunamis exist and we’re on the verge of being able to detect them.