0:00 If you throw a baseball at a solid brick wall, you know EXACTLY what happens every single time.0:07 Aye, love, it bounces straight back and hits you on the shins if you aren't careful.0:13 That's it.0:14 Simple cause and effect.0:16 Last week we looked at huge slabs of rock grinding along like a cracked eggshell on hot porridge, making whole continents drift.0:25 But today we're shrinking way down past the dirt, past the bugs, past individual atoms.0:32 Down where the usual rules pack their bags and go on holiday, right?0:37 Down where the rulebook gets tossed right in the creek.0:41 At the quantum scale, the universe stops acting like trains running on fixed tracks.0:48 You throw a quantum particle at a solid barrier, and part of the time, it just pops out on the other side.0:56 Ey up, like walking clean through the kitchen door without turning the brass knob?1:02 Swear on my tackle box, that is the honest truth.1:06 It's called quantum tunneling.1:08 And the reason it does that comes down to the big idea: particle-wave duality.1:14 Now, don't go throwing fifty-cent words at me before I've had another sup of tea.1:20 Explain that for the young ones listening.1:23 Think of an ocean wave rolling toward a wooden pier with two gaps between the pilings.1:30 What happens?1:31 Well, the wave washes through both gaps at once, ripples out on the other side, and crisscrosses itself.1:39 Makes a lovely crisscross pattern in the water.1:42 Right.1:43 But if you roll a marble through one gap, the marble only picks one lane.1:48 It's in one spot.1:50 In 1927, Clinton Davisson and Lester Germer fired tiny electrons at a nickel crystal.1:56 They expected the electrons to bounce like tiny lead buckshot.2:01 Instead, those particles formed that exact crisscross ripple pattern.2:06 Ooh!2:06 So tiny bits of matter ripple out like puddles on the flagstones?2:11 Both at the same time.2:13 Light does it, electrons do it.2:15 When you aren't looking to pin them down, they travel like waves of possibility.2:21 But the instant you detect them at a screen, they hit like a single solid speck.2:27 That sounds properly daft, Earl.2:30 It's either a pebble or a ripple.2:32 It cannot be doing two opposite things at once.2:36 Now, I know how that sounds.2:38 But hang on.2:39 That brings us to what folks call superposition.2:43 Take a shiny copper penny.2:45 You set it flat on the porch rail, it's heads or tails.2:49 But spin it like a top on the timber.2:52 What is it while it's whirling?2:54 It's a blur.2:55 Neither one nor the other.2:57 Or...2:57 well, I suppose it's a bit of both until you slap your hand down flat to stop it.3:03 That's it.3:04 That is the heart of it.3:06 Until an observation forces that particle to declare itself, its mathematical wave function contains all the possible states at once.3:16 It's not hiding the real answer under a hat; the answer genuinely doesn't exist yet.3:22 So the cat isn't just snoozing under the sofa or out in the garden.3:27 She's everywhere at once until I call her for supper.3:31 In the subatomic world, yes.3:34 Austrian physicist Erwin Schrödinger wrote down the math back in 1926 to show how that wave ripples through space.3:42 It tells you the exact odds of where the particle might turn up, but never guarantees a single point until measurement collapses that spread.3:53 It makes our tidy kitchen world seem like a clever illusion, doesn't it?3:58 We think things stay right where we put them.4:02 Our everyday world of train wheels and teakettles only looks solid because trillions of these tiny quantum pieces are bumping into each other every microsecond, forcing each other to pick a lane.4:17 Right then.4:18 So we only get our sturdy floorboards because billions of little ripples keep catching each other out.4:25 Exactly.4:26 Out here on the porch, a dropped hammer hits the oak planks every single time.4:32 But down at the very foundation of reality, the universe is fundamentally creative, fuzzy, and open-ended.4:40 Well, that's summat to dream about.4:42 Night night, sleep tight, chuck.4:45 Well.4:45 That is about the size of it.
