0:00 You ever watch creek water run beneath a railroad trestle, wondering where that current started before it hit the bend?0:09 Aye, Earl, but with a fresh brew in hand, mind, before the cat claims my lap.0:15 Last week, we sat right here wondering why ninety-five percent of our universe stays completely dark to our telescopes.0:25 But today, friend, we're fixing to back the engine all the way down the line, past every star, right up to the very start of track.0:35 Before the Big Bang itself.0:37 It sounds almost daft, doesn't it?0:40 Asking what was ticking before the clock even had a pendulum.0:45 That's the heart of it, Bridget.0:47 General relativity runs that tape backward thirteen point eight billion years, right down to an infinitely dense point — a singularity.0:58 But here's the hitch: at that point, the math breaks clean in two.1:03 Like trying to walk north of the North Pole, as folks say.1:08 The direction just stops meaning summat.1:11 Exactly.1:12 Einstein's equations give us infinities, and in physics, an infinity isn't an answer.1:19 It's the chalkboard screaming that you don't know the rules anymore.1:24 So the old physics just packs its bags and heads for the hills.1:29 It sure does.1:30 To understand that tiny speck, you need quantum mechanics — the rules of the subatomic.1:37 But quantum rules and gravity don't shake hands.1:41 They never have got on, have they?1:44 Like two stubborn goats on a narrow path.1:47 Not since day one.1:48 So researchers started building new switchbacks.1:52 Take loop quantum gravity.1:54 It treats space itself not like smooth water, but like tiny, woven chain links.2:00 You compress matter down, and those links refuse to squeeze to zero.2:06 They push back.2:07 Ooh, so it doesn't smash into nothing?2:10 It rebounds!2:11 A Big Bounce.2:12 The universe contracts down, hits that quantum floor, and springs back out like a freight car bouncing off a spring buffer.2:22 A whole prior universe collapsing before ours sparked up.2:26 That makes my head spin a treat.2:29 But what about that idea with the bubbles?2:32 You mentioned that one once over the fence.2:36 Eternal inflation.2:37 Alan Guth and Andrei Linde ran the numbers on cosmic inflation — that burst where space expanded faster than light in the first split-second.2:48 Some folks calculate that inflation never truly stops everywhere at once.2:54 It just keeps frothing away, boiling over like milk on the stove.2:59 Just like that.3:01 A vast, inflating multiverse, and our universe is just one cold bubble that dropped out of the heat.3:09 In that picture, there wasn't one beginning.3:12 There are beginnings popping off all over yonder, forever.3:17 It's lovely poetry, Earl, truly it is.3:20 But here is where my Yorkshire bone starts aching.3:24 Where's the proof, love?3:26 You can't just knit a jumper out of pure theory.3:30 Now, Bridget, that is the deepest ditch in the whole county.3:34 The cosmic microwave background — that oldest light we can take a picture of — formed three hundred and eighty thousand years after the Bang.3:46 A brick wall right across the road.3:48 A wall of glowing fog.3:50 Light couldn't travel freely before then.3:53 Photons just kept bumping into free electrons.3:57 So when we look with optical or radio dishes, we hit that wall every single time.4:03 So how on earth do you peek behind the curtain?4:07 Gravitational waves.4:09 Those ripples in space-time don't care about a fog of hot gas.4:14 They pass right through it.4:16 If we ever catch primordial tensor modes — those ancient ripples imprinted on the microwave background, maybe measured by space missions down the road — we might read the signature of that first fraction of a second.4:33 Might.4:34 But even then, can a ripple tell you what happened before time began?4:39 Or does it just tell you how hard the door slammed shut?4:44 That's the part that keeps me rocking out here till dusk.4:48 Some say asking what came before is an improper question, like asking what flavor of sweet tea a locomotive weighs.4:57 But to a researcher, not knowing isn't failure.5:01 That dark silence before the bell rang is the prettiest mystery we've got.5:07 Aye.5:07 There's real comfort in knowing the world's still bigger than our cleverest notebooks, chuck.5:15 Swear on my tackle box, Bridget, that is the honest truth.5:19 Well.5:20 That's about the size of it.5:22 Night night, sleep tight, chuck.
