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A few months ago

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the Nobel Prize in physics

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was awarded to two teams of astronomers

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for a discovery that has been hailed

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as one of the most important

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astronomical observations ever.

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And today, after briefly describing what they found,

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I'm going to tell you about a highly controversial framework

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for explaining their discovery,

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namely the possibility

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that way beyond the Earth,

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the Milky Way and other distant galaxies,

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we may find that our universe

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is not the only universe,

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but is instead

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part of a vast complex of universes

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that we call the multiverse.

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Now the idea of a multiverse is a strange one.

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I mean, most of us were raised to believe

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that the word "universe" means everything.

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And I say most of us with forethought,

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as my four-year-old daughter has heard me speak of these ideas since she was born.

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And last year I was holding her

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and I said, "Sophia,

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I love you more than anything in the universe."

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And she turned to me and said, "Daddy,

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universe or multiverse?"

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(Laughter)

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But barring such an anomalous upbringing,

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it is strange to imagine

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other realms separate from ours,

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most with fundamentally different features,

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that would rightly be called universes of their own.

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And yet,

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speculative though the idea surely is,

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I aim to convince you

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that there's reason for taking it seriously,

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as it just might be right.

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I'm going to tell the story of the multiverse in three parts.

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In part one,

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I'm going to describe those Nobel Prize-winning results

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and to highlight a profound mystery

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which those results revealed.

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In part two,

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I'll offer a solution to that mystery.

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It's based on an approach called string theory,

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and that's where the idea of the multiverse

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will come into the story.

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Finally, in part three,

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I'm going to describe a cosmological theory

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called inflation,

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which will pull all the pieces of the story together.

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Okay, part one starts back in 1929

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when the great astronomer Edwin Hubble

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realized that the distant galaxies

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were all rushing away from us,

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establishing that space itself is stretching,

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it's expanding.

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Now this was revolutionary.

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The prevailing wisdom was that on the largest of scales

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the universe was static.

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But even so,

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there was one thing that everyone was certain of:

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The expansion must be slowing down.

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That, much as the gravitational pull of the Earth

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slows the ascent of an apple tossed upward,

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the gravitational pull

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of each galaxy on every other

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must be slowing

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the expansion of space.

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Now let's fast-forward to the 1990s

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when those two teams of astronomers

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I mentioned at the outset

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were inspired by this reasoning

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to measure the rate

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at which the expansion has been slowing.

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And they did this

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by painstaking observations

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of numerous distant galaxies,

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allowing them to chart

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how the expansion rate has changed over time.

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Here's the surprise:

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They found that the expansion is not slowing down.

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Instead they found that it's speeding up,

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going faster and faster.

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That's like tossing an apple upward

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and it goes up faster and faster.

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Now if you saw an apple do that,

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you'd want to know why.

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What's pushing on it?

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Similarly, the astronomers' results

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are surely well-deserving of the Nobel Prize,

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but they raised an analogous question.

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What force is driving all galaxies

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to rush away from every other

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at an ever-quickening speed?

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Well the most promising answer

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comes from an old idea of Einstein's.

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You see, we are all used to gravity

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being a force that does one thing,

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pulls objects together.

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But in Einstein's theory of gravity,

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his general theory of relativity,

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gravity can also push things apart.

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How? Well according to Einstein's math,

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if space is uniformly filled

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with an invisible energy,

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sort of like a uniform, invisible mist,

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then the gravity generated by that mist

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would be repulsive,

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repulsive gravity,

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which is just what we need to explain the observations.

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Because the repulsive gravity

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of an invisible energy in space --

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we now call it dark energy,

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but I've made it smokey white here so you can see it --

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its repulsive gravity

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would cause each galaxy to push against every other,

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driving expansion to speed up,

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not slow down.

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And this explanation

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represents great progress.

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But I promised you a mystery

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here in part one.

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Here it is.

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When the astronomers worked out

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how much of this dark energy

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must be infusing space

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to account for the cosmic speed up,

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look at what they found.

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This number is small.

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Expressed in the relevant unit,

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it is spectacularly small.

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And the mystery is to explain this peculiar number.

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We want this number

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to emerge from the laws of physics,

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but so far no one has found a way to do that.

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Now you might wonder,

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should you care?

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Maybe explaining this number

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is just a technical issue,

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a technical detail of interest to experts,

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but of no relevance to anybody else.

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Well it surely is a technical detail,

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but some details really matter.

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Some details provide

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windows into uncharted realms of reality,

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and this peculiar number may be doing just that,

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as the only approach that's so far made headway to explain it

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invokes the possibility of other universes --

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an idea that naturally emerges from string theory,

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which takes me to part two: string theory.

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So hold the mystery of the dark energy

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in the back of your mind

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as I now go on to tell you

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three key things about string theory.

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First off, what is it?

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Well it's an approach to realize Einstein's dream

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of a unified theory of physics,

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a single overarching framework

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that would be able to describe

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all the forces at work in the universe.

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And the central idea of string theory

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is quite straightforward.

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It says that if you examine

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any piece of matter ever more finely,

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at first you'll find molecules

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and then you'll find atoms and subatomic particles.

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But the theory says that if you could probe smaller,

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much smaller than we can with existing technology,

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you'd find something else inside these particles --

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a little tiny vibrating filament of energy,

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a little tiny vibrating string.

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And just like the strings on a violin,

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they can vibrate in different patterns

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producing different musical notes.

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These little fundamental strings,

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when they vibrate in different patterns,

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they produce different kinds of particles --

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so electrons, quarks, neutrinos, photons,

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all other particles

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would be united into a single framework,

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as they would all arise from vibrating strings.

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It's a compelling picture,

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a kind of cosmic symphony,

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where all the richness

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that we see in the world around us

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emerges from the music

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that these little, tiny strings can play.

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But there's a cost

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to this elegant unification,

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because years of research

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have shown that the math of string theory doesn't quite work.

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It has internal inconsistencies,

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unless we allow

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for something wholly unfamiliar --

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extra dimensions of space.

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That is, we all know about the usual three dimensions of space.

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And you can think about those

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as height, width and depth.

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But string theory says that, on fantastically small scales,

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there are additional dimensions

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crumpled to a tiny size so small

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that we have not detected them.

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But even though the dimensions are hidden,

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they would have an impact on things that we can observe

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because the shape of the extra dimensions

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constrains how the strings can vibrate.

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And in string theory,

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vibration determines everything.

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So particle masses, the strengths of forces,

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and most importantly, the amount of dark energy

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would be determined

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by the shape of the extra dimensions.

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So if we knew the shape of the extra dimensions,

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we should be able to calculate these features,

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calculate the amount of dark energy.

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The challenge

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is we don't know

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the shape of the extra dimensions.

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All we have

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is a list of candidate shapes

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allowed by the math.

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Now when these ideas were first developed,

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there were only about five different candidate shapes,

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so you can imagine

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analyzing them one-by-one

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to determine if any yield

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the physical features we observe.

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But over time the list grew

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as researchers found other candidate shapes.

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From five, the number grew into the hundreds and then the thousands --

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A large, but still manageable, collection to analyze,

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since after all,

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graduate students need something to do.

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But then the list continued to grow

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into the millions and the billions, until today.

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The list of candidate shapes

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has soared to about 10 to the 500.

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So, what to do?

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Well some researchers lost heart,

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concluding that was so many candidate shapes for the extra dimensions,

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each giving rise to different physical features,

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string theory would never make

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definitive, testable predictions.

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But others turned this issue on its head,

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taking us to the possibility of a multiverse.

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Here's the idea.

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Maybe each of these shapes is on an equal footing with every other.

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Each is as real as every other,

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in the sense

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that there are many universes,

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each with a different shape, for the extra dimensions.

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And this radical proposal

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has a profound impact on this mystery:

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the amount of dark energy revealed by the Nobel Prize-winning results.

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Because you see,

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if there are other universes,

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and if those universes

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each have, say, a different shape for the extra dimensions,

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then the physical features of each universe will be different,

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and in particular,

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the amount of dark energy in each universe

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will be different.

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Which means that the mystery

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of explaining the amount of dark energy we've now measured

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would take on a wholly different character.

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In this context,

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the laws of physics can't explain one number for the dark energy

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because there isn't just one number,

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there are many numbers.

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Which means

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we have been asking the wrong question.

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It's that the right question to ask is,

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why do we humans find ourselves in a universe

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with a particular amount of dark energy we've measured

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instead of any of the other possibilities

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that are out there?

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And that's a question on which we can make headway.

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Because those universes

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that have much more dark energy than ours,

282
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whenever matter tries to clump into galaxies,

283
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the repulsive push of the dark energy is so strong

284
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that it blows the clump apart

285
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and galaxies don't form.

286
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And in those universes that have much less dark energy,

287
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well they collapse back on themselves so quickly

288
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that, again, galaxies don't form.

289
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And without galaxies, there are no stars, no planets

290
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and no chance

291
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for our form of life

292
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to exist in those other universes.

293
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So we find ourselves in a universe

294
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with the particular amount of dark energy we've measured

295
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simply because our universe has conditions

296
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hospitable to our form of life.

297
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And that would be that.

298
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Mystery solved,

299
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multiverse found.

300
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Now some find this explanation unsatisfying.

301
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We're used to physics

302
00:12:10,000 --> 00:12:13,000
giving us definitive explanations for the features we observe.

303
00:12:13,000 --> 00:12:15,000
But the point is,

304
00:12:15,000 --> 00:12:18,000
if the feature you're observing

305
00:12:18,000 --> 00:12:20,000
can and does take on

306
00:12:20,000 --> 00:12:22,000
a wide variety of different values

307
00:12:22,000 --> 00:12:25,000
across the wider landscape of reality,

308
00:12:25,000 --> 00:12:27,000
then thinking one explanation

309
00:12:27,000 --> 00:12:29,000
for a particular value

310
00:12:29,000 --> 00:12:32,000
is simply misguided.

311
00:12:32,000 --> 00:12:34,000
An early example

312
00:12:34,000 --> 00:12:37,000
comes from the great astronomer Johannes Kepler

313
00:12:37,000 --> 00:12:39,000
who was obsessed with understanding

314
00:12:39,000 --> 00:12:41,000
a different number --

315
00:12:41,000 --> 00:12:45,000
why the Sun is 93 million miles away from the Earth.

316
00:12:45,000 --> 00:12:48,000
And he worked for decades trying to explain this number,

317
00:12:48,000 --> 00:12:51,000
but he never succeeded, and we know why.

318
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Kepler was asking

319
00:12:53,000 --> 00:12:55,000
the wrong question.

320
00:12:55,000 --> 00:12:58,000
We now know that there are many planets

321
00:12:58,000 --> 00:13:01,000
at a wide variety of different distances from their host stars.

322
00:13:01,000 --> 00:13:04,000
So hoping that the laws of physics

323
00:13:04,000 --> 00:13:07,000
will explain one particular number, 93 million miles,

324
00:13:07,000 --> 00:13:10,000
well that is simply wrongheaded.

325
00:13:10,000 --> 00:13:12,000
Instead the right question to ask is,

326
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why do we humans find ourselves on a planet

327
00:13:15,000 --> 00:13:17,000
at this particular distance,

328
00:13:17,000 --> 00:13:20,000
instead of any of the other possibilities?

329
00:13:20,000 --> 00:13:23,000
And again, that's a question we can answer.

330
00:13:23,000 --> 00:13:26,000
Those planets which are much closer to a star like the Sun

331
00:13:26,000 --> 00:13:28,000
would be so hot

332
00:13:28,000 --> 00:13:30,000
that our form of life wouldn't exist.

333
00:13:30,000 --> 00:13:33,000
And those planets that are much farther away from the star,

334
00:13:33,000 --> 00:13:35,000
well they're so cold

335
00:13:35,000 --> 00:13:37,000
that, again, our form of life would not take hold.

336
00:13:37,000 --> 00:13:39,000
So we find ourselves

337
00:13:39,000 --> 00:13:41,000
on a planet at this particular distance

338
00:13:41,000 --> 00:13:43,000
simply because it yields conditions

339
00:13:43,000 --> 00:13:46,000
vital to our form of life.

340
00:13:46,000 --> 00:13:49,000
And when it comes to planets and their distances,

341
00:13:49,000 --> 00:13:53,000
this clearly is the right kind of reasoning.

342
00:13:53,000 --> 00:13:55,000
The point is,

343
00:13:55,000 --> 00:13:58,000
when it comes to universes and the dark energy that they contain,

344
00:13:58,000 --> 00:14:02,000
it may also be the right kind of reasoning.

345
00:14:02,000 --> 00:14:05,000
One key difference, of course,

346
00:14:05,000 --> 00:14:07,000
is we know that there are other planets out there,

347
00:14:07,000 --> 00:14:10,000
but so far I've only speculated on the possibility

348
00:14:10,000 --> 00:14:12,000
that there might be other universes.

349
00:14:12,000 --> 00:14:14,000
So to pull it all together,

350
00:14:14,000 --> 00:14:16,000
we need a mechanism

351
00:14:16,000 --> 00:14:19,000
that can actually generate other universes.

352
00:14:19,000 --> 00:14:22,000
And that takes me to my final part, part three.

353
00:14:22,000 --> 00:14:25,000
Because such a mechanism has been found

354
00:14:25,000 --> 00:14:28,000
by cosmologists trying to understand the Big Bang.

355
00:14:28,000 --> 00:14:30,000
You see, when we speak of the Big Bang,

356
00:14:30,000 --> 00:14:32,000
we often have an image

357
00:14:32,000 --> 00:14:34,000
of a kind of cosmic explosion

358
00:14:34,000 --> 00:14:36,000
that created our universe

359
00:14:36,000 --> 00:14:39,000
and set space rushing outward.

360
00:14:39,000 --> 00:14:41,000
But there's a little secret.

361
00:14:41,000 --> 00:14:44,000
The Big Bang leaves out something pretty important,

362
00:14:44,000 --> 00:14:46,000
the Bang.

363
00:14:46,000 --> 00:14:49,000
It tells us how the universe evolved after the Bang,

364
00:14:49,000 --> 00:14:51,000
but gives us no insight

365
00:14:51,000 --> 00:14:55,000
into what would have powered the Bang itself.

366
00:14:55,000 --> 00:14:57,000
And this gap was finally filled

367
00:14:57,000 --> 00:14:59,000
by an enhanced version of the Big Bang theory.

368
00:14:59,000 --> 00:15:02,000
It's called inflationary cosmology,

369
00:15:02,000 --> 00:15:06,000
which identified a particular kind of fuel

370
00:15:06,000 --> 00:15:08,000
that would naturally generate

371
00:15:08,000 --> 00:15:10,000
an outward rush of space.

372
00:15:10,000 --> 00:15:13,000
The fuel is based on something called a quantum field,

373
00:15:13,000 --> 00:15:16,000
but the only detail that matters for us

374
00:15:16,000 --> 00:15:19,000
is that this fuel proves to be so efficient

375
00:15:19,000 --> 00:15:21,000
that it's virtually impossible

376
00:15:21,000 --> 00:15:23,000
to use it all up,

377
00:15:23,000 --> 00:15:25,000
which means in the inflationary theory,

378
00:15:25,000 --> 00:15:28,000
the Big Bang giving rise to our universe

379
00:15:28,000 --> 00:15:31,000
is likely not a one-time event.

380
00:15:31,000 --> 00:15:34,000
Instead the fuel not only generated our Big Bang,

381
00:15:34,000 --> 00:15:40,000
but it would also generate countless other Big Bangs,

382
00:15:40,000 --> 00:15:43,000
each giving rise to its own separate universe

383
00:15:43,000 --> 00:15:45,000
with our universe becoming but one bubble

384
00:15:45,000 --> 00:15:48,000
in a grand cosmic bubble bath of universes.

385
00:15:48,000 --> 00:15:50,000
And now, when we meld this with string theory,

386
00:15:50,000 --> 00:15:52,000
here's the picture we're led to.

387
00:15:52,000 --> 00:15:54,000
Each of these universes has extra dimensions.

388
00:15:54,000 --> 00:15:57,000
The extra dimensions take on a wide variety of different shapes.

389
00:15:57,000 --> 00:16:00,000
The different shapes yield different physical features.

390
00:16:00,000 --> 00:16:03,000
And we find ourselves in one universe instead of another

391
00:16:03,000 --> 00:16:06,000
simply because it's only in our universe

392
00:16:06,000 --> 00:16:09,000
that the physical features, like the amount of dark energy,

393
00:16:09,000 --> 00:16:13,000
are right for our form of life to take hold.

394
00:16:13,000 --> 00:16:16,000
And this is the compelling but highly controversial picture

395
00:16:16,000 --> 00:16:18,000
of the wider cosmos

396
00:16:18,000 --> 00:16:20,000
that cutting-edge observation and theory

397
00:16:20,000 --> 00:16:24,000
have now led us to seriously consider.

398
00:16:24,000 --> 00:16:28,000
One big remaining question, of course, is,

399
00:16:28,000 --> 00:16:31,000
could we ever confirm

400
00:16:31,000 --> 00:16:34,000
the existence of other universes?

401
00:16:34,000 --> 00:16:36,000
Well let me describe

402
00:16:36,000 --> 00:16:39,000
one way that might one day happen.

403
00:16:39,000 --> 00:16:41,000
The inflationary theory

404
00:16:41,000 --> 00:16:43,000
already has strong observational support.

405
00:16:43,000 --> 00:16:45,000
Because the theory predicts

406
00:16:45,000 --> 00:16:47,000
that the Big Bang would have been so intense

407
00:16:47,000 --> 00:16:50,000
that as space rapidly expanded,

408
00:16:50,000 --> 00:16:52,000
tiny quantum jitters from the micro world

409
00:16:52,000 --> 00:16:55,000
would have been stretched out to the macro world,

410
00:16:55,000 --> 00:16:58,000
yielding a distinctive fingerprint,

411
00:16:58,000 --> 00:17:00,000
a pattern of slightly hotter spots and slightly colder spots,

412
00:17:00,000 --> 00:17:02,000
across space,

413
00:17:02,000 --> 00:17:05,000
which powerful telescopes have now observed.

414
00:17:05,000 --> 00:17:08,000
Going further, if there are other universes,

415
00:17:08,000 --> 00:17:10,000
the theory predicts that every so often

416
00:17:10,000 --> 00:17:12,000
those universes can collide.

417
00:17:12,000 --> 00:17:14,000
And if our universe got hit by another,

418
00:17:14,000 --> 00:17:16,000
that collision

419
00:17:16,000 --> 00:17:18,000
would generate an additional subtle pattern

420
00:17:18,000 --> 00:17:20,000
of temperature variations across space

421
00:17:20,000 --> 00:17:22,000
that we might one day

422
00:17:22,000 --> 00:17:24,000
be able to detect.

423
00:17:24,000 --> 00:17:27,000
And so exotic as this picture is,

424
00:17:27,000 --> 00:17:29,000
it may one day be grounded

425
00:17:29,000 --> 00:17:31,000
in observations,

426
00:17:31,000 --> 00:17:34,000
establishing the existence of other universes.

427
00:17:34,000 --> 00:17:36,000
I'll conclude

428
00:17:36,000 --> 00:17:39,000
with a striking implication

429
00:17:39,000 --> 00:17:41,000
of all these ideas

430
00:17:41,000 --> 00:17:43,000
for the very far future.

431
00:17:43,000 --> 00:17:45,000
You see, we learned

432
00:17:45,000 --> 00:17:47,000
that our universe is not static,

433
00:17:47,000 --> 00:17:49,000
that space is expanding,

434
00:17:49,000 --> 00:17:51,000
that that expansion is speeding up

435
00:17:51,000 --> 00:17:53,000
and that there might be other universes

436
00:17:53,000 --> 00:17:55,000
all by carefully examining

437
00:17:55,000 --> 00:17:57,000
faint pinpoints of starlight

438
00:17:57,000 --> 00:18:00,000
coming to us from distant galaxies.

439
00:18:00,000 --> 00:18:03,000
But because the expansion is speeding up,

440
00:18:03,000 --> 00:18:05,000
in the very far future,

441
00:18:05,000 --> 00:18:08,000
those galaxies will rush away so far and so fast

442
00:18:08,000 --> 00:18:11,000
that we won't be able to see them --

443
00:18:11,000 --> 00:18:13,000
not because of technological limitations,

444
00:18:13,000 --> 00:18:15,000
but because of the laws of physics.

445
00:18:15,000 --> 00:18:17,000
The light those galaxies emit,

446
00:18:17,000 --> 00:18:20,000
even traveling at the fastest speed, the speed of light,

447
00:18:20,000 --> 00:18:22,000
will not be able to overcome

448
00:18:22,000 --> 00:18:25,000
the ever-widening gulf between us.

449
00:18:25,000 --> 00:18:27,000
So astronomers in the far future

450
00:18:27,000 --> 00:18:29,000
looking out into deep space

451
00:18:29,000 --> 00:18:32,000
will see nothing but an endless stretch

452
00:18:32,000 --> 00:18:36,000
of static, inky, black stillness.

453
00:18:36,000 --> 00:18:38,000
And they will conclude

454
00:18:38,000 --> 00:18:40,000
that the universe is static and unchanging

455
00:18:40,000 --> 00:18:43,000
and populated by a single central oasis of matter

456
00:18:43,000 --> 00:18:45,000
that they inhabit --

457
00:18:45,000 --> 00:18:47,000
a picture of the cosmos

458
00:18:47,000 --> 00:18:50,000
that we definitively know to be wrong.

459
00:18:50,000 --> 00:18:53,000
Now maybe those future astronomers will have records

460
00:18:53,000 --> 00:18:55,000
handed down from an earlier era,

461
00:18:55,000 --> 00:18:57,000
like ours,

462
00:18:57,000 --> 00:18:59,000
attesting to an expanding cosmos

463
00:18:59,000 --> 00:19:01,000
teeming with galaxies.

464
00:19:01,000 --> 00:19:03,000
But would those future astronomers

465
00:19:03,000 --> 00:19:06,000
believe such ancient knowledge?

466
00:19:06,000 --> 00:19:08,000
Or would they believe

467
00:19:08,000 --> 00:19:11,000
in the black, static empty universe

468
00:19:11,000 --> 00:19:15,000
that their own state-of-the-art observations reveal?

469
00:19:15,000 --> 00:19:17,000
I suspect the latter.

470
00:19:17,000 --> 00:19:19,000
Which means that we are living

471
00:19:19,000 --> 00:19:22,000
through a remarkably privileged era

472
00:19:22,000 --> 00:19:24,000
when certain deep truths about the cosmos

473
00:19:24,000 --> 00:19:26,000
are still within reach

474
00:19:26,000 --> 00:19:28,000
of the human spirit of exploration.

475
00:19:28,000 --> 00:19:33,000
It appears that it may not always be that way.

476
00:19:33,000 --> 00:19:35,000
Because today's astronomers,

477
00:19:35,000 --> 00:19:38,000
by turning powerful telescopes to the sky,

478
00:19:38,000 --> 00:19:41,000
have captured a handful of starkly informative photons --

479
00:19:41,000 --> 00:19:44,000
a kind of cosmic telegram

480
00:19:44,000 --> 00:19:46,000
billions of years in transit.

481
00:19:46,000 --> 00:19:50,000
and the message echoing across the ages is clear.

482
00:19:50,000 --> 00:19:53,000
Sometimes nature guards her secrets

483
00:19:53,000 --> 00:19:55,000
with the unbreakable grip

484
00:19:55,000 --> 00:19:57,000
of physical law.

485
00:19:57,000 --> 00:20:01,000
Sometimes the true nature of reality beckons

486
00:20:01,000 --> 00:20:04,000
from just beyond the horizon.

487
00:20:04,000 --> 00:20:06,000
Thank you very much.

488
00:20:06,000 --> 00:20:10,000
(Applause)

489
00:20:10,000 --> 00:20:12,000
Chris Anderson: Brian, thank you.

490
00:20:12,000 --> 00:20:14,000
The range of ideas you've just spoken about

491
00:20:14,000 --> 00:20:17,000
are dizzying, exhilarating, incredible.

492
00:20:17,000 --> 00:20:19,000
How do you think

493
00:20:19,000 --> 00:20:21,000
of where cosmology is now,

494
00:20:21,000 --> 00:20:23,000
in a sort of historical side?

495
00:20:23,000 --> 00:20:26,000
Are we in the middle of something unusual historically in your opinion?

496
00:20:26,000 --> 00:20:28,000
BG: Well it's hard to say.

497
00:20:28,000 --> 00:20:31,000
When we learn that astronomers of the far future

498
00:20:31,000 --> 00:20:34,000
may not have enough information to figure things out,

499
00:20:34,000 --> 00:20:37,000
the natural question is, maybe we're already in that position

500
00:20:37,000 --> 00:20:40,000
and certain deep, critical features of the universe

501
00:20:40,000 --> 00:20:43,000
already have escaped our ability to understand

502
00:20:43,000 --> 00:20:45,000
because of how cosmology evolves.

503
00:20:45,000 --> 00:20:47,000
So from that perspective,

504
00:20:47,000 --> 00:20:49,000
maybe we will always be asking questions

505
00:20:49,000 --> 00:20:51,000
and never be able to fully answer them.

506
00:20:51,000 --> 00:20:53,000
On the other hand, we now can understand

507
00:20:53,000 --> 00:20:55,000
how old the universe is.

508
00:20:55,000 --> 00:20:57,000
We can understand

509
00:20:57,000 --> 00:21:00,000
how to understand the data from the microwave background radiation

510
00:21:00,000 --> 00:21:03,000
that was set down 13.72 billion years ago --

511
00:21:03,000 --> 00:21:05,000
and yet, we can do calculations today to predict how it will look

512
00:21:05,000 --> 00:21:07,000
and it matches.

513
00:21:07,000 --> 00:21:09,000
Holy cow! That's just amazing.

514
00:21:09,000 --> 00:21:12,000
So on the one hand, it's just incredible where we've gotten,

515
00:21:12,000 --> 00:21:16,000
but who knows what sort of blocks we may find in the future.

516
00:21:16,000 --> 00:21:19,000
CA: You're going to be around for the next few days.

517
00:21:19,000 --> 00:21:21,000
Maybe some of these conversations can continue.

518
00:21:21,000 --> 00:21:23,000
Thank you. Thank you, Brian. (BG: My pleasure.)

519
00:21:23,000 --> 00:21:26,000
(Applause)