Why Is Everything Made Of Atoms?
Why Is Everything Made Of Atoms?
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Researched and Written by Colin Stuart
Check out his superb Astrophysics for Beginners course here: https://www.colinstuart.net/astrophys…
Narrated and Edited by David Kelly
Animations by Manuel Rubio
Incredible thumbnail art by Ettore Mazza, the GOAT: https://www.instagram.com/ettore.mazz…
Proton visualization courtesy of MIT, Jefferson Labs, and Sputnik Animation, Copyright © MIT and Jefferson Lab, 2021, All Rights Reserved
Stock footage taken from Videoblocks and Artgrid, music from Epidemic Sound, Artlist and Silver Maple. Space imagery also used from NASA and ESO.
Image Credits:
Heavy Ion Collider By Z22 - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index…
Dark Energy Survey By Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURAAcknowledgments: T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab) \u0026amp; D. de Martin (NSF’s NOIRLab) - https://noirlab.edu/public/images/noi…, CC BY 4.0, https://commons.wikimedia.org/w/index…
00:00 Introduction
05:06 The First Light In The Universe
12:17 The Weirdest Object In The Universe
25:59 Seeing The Big Bang
35:55 Why Atoms?
#recombination #quantum
Content
0.789 -> “If, in some cataclysm, all of scientific
knowledge were to be destroyed, and only one
5.79 -> sentence passed on to the next generations
of creatures, what statement would contain
10.3 -> the most information in the fewest words?
13.677 -> I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it)
19.218 -> that all things are made of atoms.”
25.42 -> 5
26.862 -> 4
28.006 -> 3
29.355 -> 2
30.778 -> 1
33.647 -> The ship rattles as it stretches out into
35.647 -> the void, beginning the adventure of a lifetime.
39.715 -> The nervous crew are off on an epic journey
42.28 -> to visit their home world's only natural satellite.
Though similar in concept to the journey undertaken
47.77 -> by the Apollo astronauts when they left Earth
for the Moon - this voyage is very different.
53.52 -> When Armstrong and Aldrin headed for history
on the lunar surface, they needed only to
57.93 -> travel a distance equal to the width of thirty
Earths.
61.329 -> Our intrepid travellers must cover a distance
equal to more than 63,000 times the diameter
67.34 -> of their home world.
Compared to the crew´s destination though,
70.979 -> the Moon is a celestial snail. It crawls around
the Earth once a month at a speed of 1000
77.26 -> metres per second. That may sound fast, but
this satellite is whipping around at over
82.17 -> two million metres per second or just under
one per cent the speed of light. It's moving
87.259 -> so quickly that it completes 6.5 quadrillion
orbits each and every second.
94.61 -> For it is no moon.
97.592 -> And this is no solar system.
102.909 -> Our travellers are not exploring the astronomical
realm, but the atomic one.
108.259 -> They are brave atomonauts, adrift inside the
hydrogen atom. Departing from the solitary
114.549 -> proton at its centre, they are in search of
the lone electron that encircles it.
125.4 -> But their mission is a lot harder than it
first appears. The electron only orbits the
131.14 -> proton like a moon orbits a planet in the
simplified Bohr model of the atom, named after
136.59 -> the Danish physicist Niels Bohr. Modern quantum
physics says that we can never know for certain
142.11 -> where the electron actually is – we can
only say where it's most likely to be. The
147.42 -> blur of all its possible paths creates a cloud
around the nucleus. Our atomonauts could therefore
153.37 -> never land at their destination - only float
into the fog of possibility.
163.77 -> These atoms are the universe's lego bricks.
Vast galaxies swirl in the void and distant
172.06 -> stars keep vigil over the night, but they
are all built out of atoms. As we all are.
178.46 -> Indeed, there's an entire cosmos inside you.
The number of atoms in your body alone exceeds
185.45 -> the total number of stars in the entire observable
universe. Even if you started counting them
190.64 -> at a rate of a billion a second, it would
still take you far longer than the current
194.48 -> age of the universe to complete the task.
And as we have seen - even within those atoms
200.959 -> themselves, there are entire complex systems
to explore.
205.349 -> And yet… at the very beginning of time the
number of atoms in the universe was precisely
211.29 -> zero.
Not a single atom in the entirety of the cosmos.
216.95 -> So how did we end up here?
Where did the very first atom come from?
223.49 -> And just why is everything made of atoms?
237.106 -> The earth weighs about 6.58 billion trillion
240.384 -> tons, and about 1.85 billion billion of that
is carbon.
244.59 -> The climate can sometimes feels like an impossibly
big problem for one person to try and solve.
249.77 -> And yet that is where Wren comes in, our sponsor
today.
253.29 -> Wren is a website where you can calculate
your carbon footprint, then offset it by funding
258.01 -> a mix of carbon reduction projects like tree
planting, mineral weathering and rainforest
262.82 -> protection.
By answering a few simple questions about
265.29 -> your lifestyle you can find out your carbon
footprint, and how to reduce it - and then
269.28 -> you can actually offset what you have left
over.
272.25 -> You receive regular updates on what you support
- one particularly impressive project is Biochar
277.669 -> in California - which prevents wildfires by
removing dead and flammable trees, then turning
282.79 -> the biomass into biochar, thus stopping it
from ending up in the atmosphere. A cutting
288.12 -> edge way to tackle the climate.
So, offset your carbon footprint on Wren.
293.55 -> The first 100 people who sign up using the
link in the
296.07 -> description, will have 10 extra trees planted
in their name.
299.43 -> Thanks to Wren for supporting educational
content on youtube.
309.306 -> A wicked wind howls across the Black Sea.
Waves swell and crash as the previously mirror
314.93 -> smooth water is tossed and churned.
Marooned on a kayak amid this maelstrom is
320.8 -> a pair of newly-weds.
323.043 -> They are refugees, fleeing Ukraine to escape
326.389 -> from the Russian regime.
Yet this is not a twenty-first century story.
331.45 -> The year is 1932 and the couple stranded in
the tumult are the physicist George Gamow
337.44 -> and his wife Lyubov, who he affectionately
calls Rho after the Greek letter.
342.47 -> What could drive this young couple to risk
their lives on such a perilous voyage?
348.699 -> The early 1930s witnessed a big shift in the
way the Soviets treated their scientists and
353.77 -> intellectual ideas and foreign trips were
increasingly tightly policed. Gamow wants
358.56 -> to present his research at a large scientific
conference in Rome, but needs a new passport.
364.28 -> His application is constantly kicked into
the long grass by bureaucrats in Leningrad
368.53 -> who promise progress, but instead deliberately
run down the clock. He never goes to the Italian
374.03 -> capital.
Yet his endless visits to the passport office
376.87 -> have one significant upside: it is there that
he meets Rho. They marry soon after and within
383.5 -> a year the newly-weds agree to flee. They
pore over maps looking for the surest means
388.729 -> of escape from the Soviet Union.
And so they settle on the Black Sea, leaving
393.099 -> Gamow's birthplace of Odessa to head for Turkey.
Gamow still has a Danish motorcycle licence
397.96 -> from his days collaborating with the physicist
Niels Bohr in Copenhagen, and so the plan
402.46 -> is to wash up on a Turkish beach, pretend
to be Danish and ask to be taken to the Danish
406.669 -> embassy in Istanbul.
Their journey couldn't have started better.
411.34 -> The water is calm and the breeze is gentle.
But when they awake before sunrise the second
416 -> day the weather is already turning. By the
evening, the situation intensifies and soon
422.229 -> becomes perilous. By the time the storm abates
they are exhausted to the point of hallucination.
428.289 -> Drifting alone on the open water, strong winds
buffet the boat all the way back to Crimea.
437.94 -> Despite this setback, eventually Gamow and
Rho do escape. They secure passage to a scientific
442.729 -> conference in Belgium and after the conference,
Marie Curie helps the couple extend their
447.139 -> stay in Western Europe. Never to return to
the Soviet Union, they finally headed to the
452.82 -> United States in early 1934.
This entire odyssey has unfolded before Gamow's
458.68 -> thirtieth birthday.
Six years later, Gamow is granted American
463.51 -> citizenship. Free from the shackles of oppression,
he is now able to continue his work.
469.43 -> And it is this work that would turn out to
be pivotal in our understanding of physics
474.22 -> - for it would change the way we think about
the history of the universe forever.
482.93 -> In 1929, three years before Gamow's exploits
on the Black Sea, the American astronomer
488.349 -> Edwin Hubble had shocked the astronomical
establishment with evidence that the universe
493.33 -> is expanding. If the universe is growing day
by day then it was smaller yesterday and smaller
499.74 -> still a week ago. Keep rewinding the clock
and there was a time when every part of the
504.99 -> modern universe was concentrated down into
an incredibly small space before it expanded
510.419 -> outwards. The Big Bang.
Except that it wasn't such a new idea to Gamow.
516.09 -> The Russian physicist Alexander Friedmann
had already predicted the universe's expansion
520.519 -> back in 1925 and the pair had lengthy discussions
about it during Gamow's time in Leningrad.
526.16 -> Gamow spent much of his early time in America
working on something else – the ultimate
532.32 -> power source of stars. Yet the focus of his
attention was shifting. In October 1945, Gamow
540.49 -> writes a letter to his old friend Niels Bohr
to mark the Dane's 60th birthday.
545.41 -> The letter reveals that Gamow was starting
to apply his work on the internal mechanics
550.269 -> of stars to the origin of matter in the early
universe immediately after the Big Bang.
560.089 -> Up until this point cosmologists had assumed
that the early universe was dominated by matter,
565.45 -> the stuff that all visible structure is made
of, from stars and planets to galaxies and
569.82 -> galaxy clusters. Yet Gamow began to suspect
otherwise. History wavers on who truly deserves
576.519 -> the credit, but it could have been Gamow's
student Ralph Alpher. In his doctoral dissertation
582.019 -> Alpher claimed that the early universe wasn't
dominated by matter, but by electromagnetic
587.21 -> radiation. This electromagnetic radiation
would supposedly dominate the early universe
592.64 -> for a full fifty thousand years after the
Big Bang.
597.33 -> Physicists have another word for electromagnetic
radiation: light. We may use that word for
604.19 -> the light our eyes can see, but there's more
to it than that.
608.57 -> Just as there are frequencies of sound too
low or high for our ears to hear, there are
613.31 -> frequencies of light too low or high for us
to see.
618.54 -> When a physicist uses the word light they
mean the radiation that spans the full range
622.769 -> of these frequencies, from gamma-rays and
X-rays at the high frequency end to microwaves
628.04 -> and radio waves at the other. When you use
a microwave to heat your dinner, you're actually
632.93 -> cooking the food using low-frequency light.
And so light and matter were trapped together
639.06 -> in the nascent universe. After 100,000 seconds
of expansion, the entire universe was still
645.93 -> denser than the air you're breathing right
now - and continued for thousands of years
651.19 -> to be dense enough for sound waves to travel
through.
654.44 -> Sound waves of such low frequency that they'd
need to be squashed by 100 septillion times
658.619 -> – that's 1 followed by 26 zeroes – just
to push them into the range of human hearing
663.43 -> - something that in 2013 John G Cramer at
Washington University used data from the early
670.34 -> universe to reproduce:
682.074 -> Cosmologists call these sound waves baryon
685.12 -> acoustic oscillations and they can still be
detected today using facilities such as the
690.54 -> Sloan Digital Sky Survey. As the universe
kept expanding it continued to stretch out
696.079 -> these sound waves, shifting them to ever lower
frequencies.
700.25 -> But then there came a point when everything
changed.
707.089 -> It is one of the most important events in
the entire history of the universe – and
712.39 -> it was predicted by none other than Alpher
and Gamow. It is called recombination and
719.74 -> it also opened the floodgates for the first
light to come streaming out into the early
724.841 -> universe.
But what recombined exactly?
729.99 -> And what does this first light have to do
with the first atom?
740.72 -> The feeling of claustrophobia rises by the
second. You're trapped.
745.52 -> Whichever way you turn just leads to a blocked
path.
748.51 -> Have you seen these walls before? Did you
turn right or left at this junction earlier?
753.26 -> No matter how hard you try, you just can't
figure out how to escape.
757.16 -> And that is not surprising.
Because there is no escape.
762.57 -> You are trapped in an impenetrable maze.
This series of never-ending dead-ends is exactly
770.279 -> what light encountered after the Big Bang.
Everywhere light tried to go it bumped into
775.209 -> insurmountable obstacles in the form of sub-atomic
particles. And yet the universe didn't begin
780.889 -> as such a labyrinth. In the very beginning
there was none of this matter to get in the
785.74 -> way. For the faintest sliver of a second,
just after its birth, it was free.
792.24 -> But very quickly light turned into its own
captor, snapping the shackles shut on itself.
799.699 -> This happened because light leads a double
life. Like the vampires and werewolves of
804.209 -> myth and folklore it can shape-shift into
something else: matter. Light is a form of
810.86 -> energy, and energy and matter are two sides
of the same cosmic coin. They are completely
815.6 -> interchangeable. And the more energetic the
light, the higher the likelihood it will change
819.62 -> into matter.
Within a trillionth of a second after the
822.94 -> Big Bang some of the universe's energy is
converted into particles of matter that start
828.02 -> popping into existence, flooding the universe
with fundamental particles - everything needed
833.69 -> to build atoms, including electrons. Yet we'll
still have to wait hundreds of thousands of
839 -> years for these particles to actually coalesce
into the first atom.
843.34 -> We may already have electrons, but to make
a hydrogen atom, like the one explored by
847.38 -> our atomonauts, we also need a proton. Unlike
electrons, they are built out of something
853.339 -> else: quarks – fundamental particles that
also appeared during light's partial metamorphosis
860.99 -> into matter.
Quarks come in a menu of different flavours,
864.37 -> but the most important ones for our story
of atom formation are the up quark and the
868.86 -> down quark. Up quarks carry a positive charge
and down quarks a negative charge. A proton
875.12 -> is made of two up quarks and one down quark,
giving a proton an overall positive charge.
881.16 -> Yet these quarks are not natural bedfellows.
Electric charges act like the poles of a magnet
887.67 -> – opposites attract, but like charges repel
one another. How can two positively charged
894.07 -> up quarks happily sit side by side inside
a proton?
901.54 -> The solution to this puzzle lies with forces,
the glue needed to stick the first atom together.
908.44 -> Physicists know of four fundamental forces
in the universe. Two are familiar to us: gravity
913.36 -> and electromagnetism. Light is an electromagnetic
wave and it is electromagnetism that repels
919.38 -> like magnets and quarks from one another.
Down in the atomic world, two less familiar
925.14 -> forces are at a play. The weak nuclear force
governs radioactivity, but it's the strong
931.44 -> nuclear force that really dominates here.
It is one duodecillion times stronger than
937.73 -> gravity. That's ten followed by thirty-eight
zeroes – significantly more zeroes than
942.38 -> there are stars in the entire observable universe.
The strong nuclear force is also one hundred
948.569 -> times stronger than the electromagnetic force.
So two quarks with the same charge may want
953.839 -> to push away from one another, but the strong
nuclear force can override this electromagnetic
959.56 -> instinct and keep them tied together.
There is a catch, though.
965.579 -> The strong nuclear force may be the king of
the forces, but the kingdom it governs is
971.139 -> tiny. It only has dominion over the most minute
of distances: about a trillionth of a millimetre.
980.19 -> Initially energies are too high for quarks
to bind together through the strong force.
984.9 -> When the quarks first formed, the temperature
of the universe was over one quadrillion degrees.
989.38 -> Though they pass very close to each other,
the quarks collide with such high energy that
994.71 -> they cannot stick.
But the new universe is expanding all the
999.69 -> time. It cools as it grows and particles within
it slow down. After the first millionth of
1005.11 -> a second the temperature drops to a mere one
trillion degrees and the first protons are
1010.209 -> able to form. Neutrons form too, the other
kind of particle you'll find in an atomic
1016.11 -> nucleus. They are made of one up quark and
two down quarks.
1021.149 -> Simple enough, you might think.
But again, as with Bohr´s model of the atom,
1027.23 -> neutrons and protons are not quite that straightforward.
1033.927 -> Indeed, the more physicists learn about the proton, the more downright weird it gets.
1039.767 -> To quote Mike Williams, physicist at the Massachusetts Institute of Technology:
“This is the most complicated thing that
1047.28 -> you could possibly imagine,”
For one thing, together the three quarks – known
1052.13 -> as valence quarks - actually make up just
one per cent of the proton's mass. The rest
1058.12 -> is taken up by particles called gluons. They
are the particles that carry the strong nuclear
1063.41 -> force. It's by exchanging gluons that the
trio of valence quarks are able to bind together
1069.919 -> into a proton.
Yet it gets a lot stranger. Occasionally gluons
1074.88 -> pick up enough energy that they can do some
shape-shifting of their own, turning into
1079.17 -> a quark and its antimatter equivalent the
anti-quark. These so-called “sea quarks”
1085.96 -> then quickly recombine back into a gluon.
So at any one time a proton is really a blur
1092.19 -> of valence quarks, gluons and sea quarks.
We still don't understand all the details
1098.35 -> and experiments like the Relativistic Heavy
Ion Collider in New York are helping physicists
1103.55 -> probe deeper inside the proton.
What we do know is that gluons and sea quarks
1107.74 -> make up 99 percent of the proton's mass. Because
they aren't permanent, physicists refer to
1113.99 -> the sea quarks as virtual particles. This
means that the mass of the proton – the
1119.1 -> particle you'll find at the centre of every
atom in the universe – mostly comes from
1124.27 -> an infinity of sea quarks that don't actually
exist.
1130.159 -> From top and bottom, strange to charm, a whole
range of quarks can be found as sea quarks,
1135.71 -> popping in and out of existence for just short
enough periods to not break conservation of
1140.53 -> energy.
A recent experiment at the University of Milan
1144.44 -> has even shown that sometimes charm quarks
actually appear at lower energies.
1149.93 -> And most bizarrely, charm quarks have almost
1 and a half times the mass of the entire
1156.89 -> proton - the low probability of this happening
meaning that their full mass isn´t added
1162.12 -> to the proton itself. The quantum world of
the very small is a counterintuitive place.
1174.33 -> Returning to the universe's timeline - now
that we have protons and neutrons, the next
1178.72 -> stop on our journey to the first atom comes
as the universe continues to cool and expand,
1184.21 -> meaning the protons and neutrons lose speed.
And it is here that George Gamow re-enters
1190.39 -> our story.
In 1948 he has a letter published in the scientific
1194.669 -> journal Physical Review Letters. It runs to
no more than a page, but its length belies
1200.63 -> the magnitude of its insights.
The paper suggests that within a handful of
1205.13 -> minutes of the Big Bang the universe cooled
to a billion degrees, enough to allow the
1210.03 -> strong nuclear force to stick a proton to
a neutron. This proton-neutron pair is known
1216.6 -> as a deuteron and it's the gateway to a whole
new way of building structure in the infant
1223.03 -> universe.
Stars like the Sun generate vast amounts of
1226.24 -> light by churning hydrogen into helium through
a process called nuclear fusion. Slightly
1231.751 -> less helium comes out than the amount of hydrogen
that goes in and the difference is converted
1236.289 -> into sunshine as mass turns back into energy.
Along with Ralph Alpher, Gamow was the first
1242.15 -> to figure out the series of steps by which
fusion turns hydrogen into helium - and deuterons
1248.23 -> played a crucial role - for when a deuteron
combines with a proton it makes the nucleus
1252.82 -> of a helium-3 atom. Then when two helium-3
nuclei fuse they make the nucleus of a helium-4
1259.549 -> atom, and two extra neutrons. In the modern
universe these reactions can only unfold in
1264.32 -> places with extremes of temperature and pressure
like the cores of stars.
1268.7 -> But similar temperatures were present universe
wide soon after the Big Bang, though not for
1274.13 -> long. There was only an incredibly short window
of opportunity for fusion to take place. The
1279.82 -> temperature had to be cool enough for deuterons
to form in the first place, but still hot
1284.36 -> enough to fuse everything else together.
And that window opened less than a second
1289.24 -> after the Big Bang and slammed about twenty
minutes later when the temperature of the
1294.77 -> universe cooled. A roughly twenty minute period
in which about a quarter of the universe's
1299.98 -> mass of hydrogen nuclei turned into helium
nuclei.
1306.419 -> And so we have a universe that's still just
20 minutes old, sprinkled with twelve hydrogen
1312.23 -> nuclei for every one helium nucleus and a
billion particles of light for every nucleus.
1318.82 -> Incredible progress in just over a quarter
of an hour.
1321.86 -> But we still don't have the first atom.
For that we need to bind electrons in orbit
1329.429 -> around these nuclei.
And that would take a very long time indeed.
1335.309 -> Electrons are negatively charged and protons
make atomic nuclei positively charged. Opposites
1340.641 -> attract and so the electromagnetic force can
snare a passing electron and trap it in orbit
1345.9 -> around the nucleus.
But the electromagnetic force is one hundred
1349.929 -> times weaker than the strong nuclear force
- so the universe has to cool all the way
1354.97 -> down to just 4000 degrees in order for the
particles to slow down enough for the electromagnetic
1360.83 -> force to do its thing.
It will take 380,000 years of expansion after
1367.33 -> the Big Bang until the universe reaches this
point.
1369.12 -> Then, finally, the first atom forms.
But as with the bizarre components of its
1377.059 -> nucleus, adding electrons certainly doesn´t
make things any less complicated.
1384.25 -> Electrons were discovered towards the end
of the 19th century, yet time has only burnished
1388.6 -> their enigma. At almost two thousand times
lighter than a proton, an electron is generally
1393.31 -> thought to be a single point with no shape
or internal structure - truly fundamental,
1399.98 -> like quarks.
They don't orbit the nucleus like planets
1402.809 -> around the Sun, either. Quantum physics tells
us that it is impossible to know both the
1407.57 -> position and speed of an electron with perfect
accuracy. At any one time an electron isn't
1413.32 -> in one spot around the nucleus - it simultaneously
occupies every possible spot. A single electron
1421.669 -> envelops the nucleus like a fog and we can
only talk about where it is most likely to
1426.9 -> be.
Electrons, as with all other fundamental particles,
1430.85 -> also have a curious property called 'spin'.
They are deflected by magnetic fields as if
1436.6 -> they were rotating balls of charge.
This rotation is counterintuitive. If you
1441.82 -> spin around 360 degrees – in other words
rotate through a full circle – then you'd
1446.47 -> return to where you started. You're a spin
1 entity. But electrons are spin ½ entities
1453.539 -> – they have to be rotated through 720 degrees
to return to where they started. Except that
1459.77 -> electrons aren't actually spinning at all
– quantum physics forbids it. Though it
1464.399 -> is useful to think of them as spinning, they
can't be.
1471.44 -> And so everywhere we look, the inside of an
atom is like a giant hall of mirrors. Deception,
1479.02 -> illusion and subterfuge accompany each of
our endeavours to understand it - a bizarre
1484.12 -> quantum realm that runs counter to common
sense, wrapped up in mysteries that we are
1488.58 -> very far from unravelling.
But what we do know is that the formation
1492.88 -> of the first atoms some 380,000 after the
Big Bang set light free.
1501.24 -> Photons of light now have a way out of the
previously impenetrable maze that they had
1505.7 -> inflicted upon themselves.
With electrons suddenly sucked into orbits
1509.78 -> around atomic nuclei, there is an abrupt increase
in the space between matter. Light can travel
1515.07 -> without whacking into anything, and off it
goes at 299 792 458 m / s.
1524.46 -> In 1948 Ralph Alpher and Robert Herman built
on this work and predicted that this first
1530.86 -> light to flood out in the universe hundreds
of millennia after the Big Bang should still
1536.169 -> be visible today.
And finding it would be the equivalent of
1540.07 -> a smoking gun, a hard-to-argue-with proof
that the universe really did begin with a
1545.51 -> hot Big Bang.
Unfortunately, no-one took much notice and
1550.65 -> the idea was largely forgotten about for a
decade and a half.
1556.025 -> Until...
1562.827 -> A fresh-faced Robert Dicke stands on the roof
1565.34 -> of the Radiation Laboratory at the Massachusetts
Institute of Technology, holding a device
1570.809 -> of his own making aloft.
Dicke joined MIT under a cloak of secrecy
1576.71 -> in September 1941 having only just completed
his PhD at the age of 25. The Second World
1583.549 -> War has been raging for two years, and although
the United States remains neutral, it is starting
1588.929 -> to make preparations for joining the fray.
They were right to. Within weeks of Dicke
1593.79 -> starting at MIT, the Japanese attack Pearl
Harbour and the United States enters the war
1599.809 -> the very next day.
Dicke is a keen inventor with a real skill
1603.929 -> for electronics. It's in the blood – his
father was a patent attorney and Dicke Jr
1609.07 -> would go on to file over 50 patents in his
lifetime, for devices from clothes dryers
1613.77 -> to lasers.
But at MIT Dicke is working on radar.
1621.16 -> The term radar - an acronym for RAdio Detection
And Ranging – was coined by the US Navy
1626.049 -> just the year before. By sending out short
pulses of radio waves, you can detect objects
1630.63 -> like enemy aircraft when they reflect those
radio waves back to you. Except that radar
1636.13 -> was initially a pretty blunt instrument.
Radio waves are a form of light, part of the
1641.77 -> electromagnetic spectrum. They have the longest
wavelength of any light – the distance over
1646.309 -> which the wave repeats itself. Radar has been
around since the 1930s, but Dicke is working
1651.65 -> on a big improvement: using microwaves instead.
Microwaves have a shorter wavelength than
1657.61 -> radio waves, meaning your radar picture will
show greater detail. Dicke invents a new receiver
1663.59 -> to pick up these reflected microwaves, now
called the Dicke radiometer.
1668.779 -> Yet the curious child within him can't help
but look even further up, beyond the bombers
1675.12 -> and the dogfighters, to space. Dicke wonders
whether any microwaves are coming from the
1682.429 -> cosmos.
And so here he is, on the roof of the Radiation
1686.309 -> Laboratory of MIT, pointing his radiometer
to the sky.
1692.98 -> It's an idea he would return to over a decade
later at Princeton as part of one of the most
1697.87 -> important insights in 20th century cosmology.
Ultimately it would validate our story of
1704.12 -> the origin of the very first atoms.
As with many of us, Dicke finds the idea of
1709.769 -> the Big Bang a little conceptually troubling.
How can something come from nothing is perhaps
1714.43 -> the most asked question about the universe's
origin. So Dicke explores the idea of cyclical
1719.649 -> universes - an expanding universe that slows,
stops and shrinks, collapsing back in on itself
1726.289 -> in a Big Crunch, only to explode outwards
again in another Big Bang.
1731.59 -> A collapsing universe would get exceptionally
hot as matter crushed down on itself. Electrons
1737.309 -> would get ripped away from protons as the
universe returned to a sea of sub-atomic shrapnel.
1742.809 -> Dicke dubs this mega-hot maelstrom a “fireball”.
The ensuing bounce and expansion would cool
1749.07 -> the fireball back down and allow atoms to
reform – and this is where the name “recombination”
1755.679 -> originates. In this theory the atoms truly
would recombine.
1760.88 -> By thinking this scenario through, Dicke,
like Gamow over a decade earlier, hits upon
1766.83 -> the notion that there should be relic radiation
left over from this super-hot stage and that
1772.279 -> it would still be visible today. He calls
it fireball radiation. It's the same radiation
1779.07 -> from recombination that Gamow and his colleagues
predicted back in 1948, although Dicke is
1785.36 -> initially unaware of their work. Dicke reasons
that this fireball radiation should now be
1794.159 -> in the microwave part of the electromagnetic
spectrum - the very part he has spent two
1799.909 -> decades working on.
Of course initially the leftover light from
1804.46 -> the Big Bang would have been in the visible
part of the spectrum. Had anyone been around
1808.9 -> to see it, it would have glowed yellow-orange.
But the universe has continued to expand ever
1814.659 -> since the light was released 13.42 billion
years ago. That expansion has stretched the
1820.049 -> space between everything, also redshifting
any waves of electromagnetic radiation travelling
1825.559 -> through that space.
Dicke calculates that his fireball radiation
1829.21 -> would have been stretched right out through
the infra-red and into the microwave spectrum.
1835.289 -> And so he resolves to find it with his eponymous
radiometer and begins to plan an observation
1841.07 -> run that would start in the mid-1960s.
But something strange happens before he has
1847.51 -> a chance to finish his work.
Forty five minutes drive away in Holmdel,
1853.22 -> New Jersey, two radio astronomers are attempting
a different kind of experiment. Their names
1858.87 -> are Arno Penzias and Robert Wilson. Like Gamow
before him, Penzias fled European totalitarianism
1865.33 -> – a child evacuee from 1930s Germany.
1867.94 -> Penzias and Wilson are using the giant six
1870.75 -> metre Holmdel Horn Antenna, part of Bell Telephone
Laboratories, to listen out for radio waves
1877.11 -> reflected off orbiting satellites.
The signals they are looking for are faint
1882.279 -> – to hear them they must first get rid of
any other interference. They eliminate local
1887.07 -> radar and radio transmission and even remove
interference from the receiver itself by cooling
1892.39 -> it to −269 degrees Celsius using liquid
helium.
1897.45 -> Yet despite their best efforts there remains
an annoying hissing in the detector, like
1901.93 -> the static between channels on an old radio.
It seems to be coming from all over the sky.
1909.029 -> It is then they spot what must be the culprit.
Penzias and Wilson discover pigeons roosting
1919.429 -> in the antenna.
The heat from their droppings – what they
1925.46 -> would later call a “white dielectric material”
- must be creating the noise. The pigeons
1931.299 -> are carefully trapped and sent to the town
of Whippany 30 miles away, only for them to
1935.33 -> fly right back. In the end they sadly meet
their demise. Penzias and Wilson meticulously
1941.08 -> clean out their droppings.
But the hissing remains.
1945.059 -> In all, Penzias and Wilson spend over a year
trying to figure out the source of this maddening
1952.49 -> interference. Desperate, Penzias starts phoning
round, asking others if they have any idea
1957 -> what's going on. One day he phones Dicke at
Princeton. Dicke is in his office, in the
1960.08 -> middle of a meeting about building his device
to look for the fireball radiation. As soon
1964.37 -> as he hears what Penzias has to say his heart
sinks. “Well, boys, we’ve been scooped,”
1968.41 -> he says to his colleagues.
Penzias and Wilson pick up the 1978 Nobel
1977.28 -> Prize in Physics for their serendipity and
Dicke is left empty-handed. Gamow would never
1983.12 -> win a Nobel either.
And so ends the story of the discovery of
1988.289 -> the cosmic microwave background. The unmistakable
fingerprint of the formation of the first
1994.69 -> atoms. Undeniable proof that our universe
started with a hot Big Bang.
2004.29 -> As the earliest light dispatched into the
universe, it is an image of an infant cosmos.
2009.74 -> If our present universe were a forty year
old human, the cosmic microwave background
2014.59 -> is the equivalent of a photograph taken when
it was less than ten hours old.
2019.65 -> Hidden within it are clues to the universe's
future, our present. Small temperature variations
2025.559 -> signal the existence of tiny differences in
density in the infant universe. The more matter
2030.659 -> that falls into these densities, the bigger
they get and in turn the more matter that
2035.33 -> falls in. Within a few hundred million years
the first galaxies will form as matter relentlessly
2040.77 -> clumps together. And as well as this, marked
across this map of the cosmos, now stretched
2046.049 -> to almost 500 million light years in diameter,
are the imprints of the sound waves of the
2051.859 -> early universe. The remains of the Baryon
Acoustic Oscillations.
2058.089 -> Experiments such as the Dark Energy Survey,
high up in the Chilean Andes, have mapped
2062.29 -> the layout of the modern universe like never
before. Vast superclusters of galaxies stretch
2068.57 -> out among equally gigantic supervoids, which
mirror the tiny temperature variations seen
2074.859 -> in the Cosmic Microwave Background. The seeds
of the universe's structure were sown long
2081.429 -> ago.
But you don't need a giant horn antenna to
2087.619 -> tune into the universe's youth. An old, analogue
television set will suffice. In our modern
2095.579 -> digital age memories are fading of the snow
that would settle across the screen as you
2100.14 -> twiddled between channels. One percent of
that interference is the cosmic microwave
2106 -> background.
The universe began almost 14 billion years
2112.079 -> ago, but the formation of the first atom was
such a monumental moment in its history that
2117.24 -> echoes of the event remain our invisible companions
throughout our lives and will take trillions
2122.73 -> of years of expansion yet to be stretched
out beyond our view.
2127.89 -> And so you may be forgiven for thinking that
the rise of the atom was inevitable. That
2132.86 -> they are the inescapable fate of a universe
made of light and matter, the final destination
2134.89 -> of any hot dense soup of particles, as fundamental
to reality as their constituent parts.
2141.38 -> But that is certainly not the case.
In fact, it is quite the opposite.
2156.543 -> With the blindfold covering your eyes, your
other senses are heightened.
2161.93 -> You hear every click and snap as the guns
are loaded - all two dozen of them.
2167.76 -> You are about to be executed by firing squad.
The soldiers raise their weapons and aim the
2173.73 -> barrels squarely at your chest.
2176.328 -> This is it, you think, and your body braces
2179.27 -> for its last breath.
Then every single bullet misses.
2190.27 -> The Canadian philosopher and author John Leslie
asks us to imagine a version of this scenario
2195.57 -> in his 1989 book Universes. How unlikely it
seems, that you're still alive. It only needed
2202.86 -> one shot to hit its target and yet every single
shooter missed. You owe your existence to
2208.66 -> an incredibly precise and improbable sequence
of events. Any deviation from it and you simply
2215.319 -> wouldn't be here.
The story of our universe – and of its atoms
2219.2 -> – is a similar tale. Since its birth 13.8
billion years ago, the universe has gone from
2225.15 -> having no atoms at all to being full of more
atoms than we could possibly count in trillions
2231.17 -> of lifetimes. The atom is so ubiquitous that
we take it for granted. Atoms, after all,
2236.98 -> are everywhere.
And yet the atom is a most ludicrously unlikely
2240.99 -> entity. Like your life in that courtyard,
it teeters on a tightrope so fine that any
2246.4 -> miniscule mis-step would see it snuffed out
in an instant. Mess with the physics even
2251.98 -> slightly and every trace of chemistry and
biology would fade away.
2260.05 -> Imagine that you could operate the universe
using a giant control panel.
2265.37 -> Littered with knobs, dials and switches - each
one responsible for some key property of existence.
2271.04 -> The masses of certain sub-atomic particles;
the strengths of various forces.
2275.25 -> In this scenario It wouldn't take much tinkering
to destroy atoms entirely and make the journey
2281.69 -> of our erstwhile atomonauts impossible.
For an atom to be stable, the orbits of its
2284.71 -> electrons need to be a lot bigger than the
size of the nucleus. Otherwise the electrons
2289.41 -> risk crashing down on the atomonauts' homeworld
of the proton, like a satellite dragged back
2294.77 -> to Earth in fire and fury. You'd only have
to make the electromagnetic force a little
2299.8 -> bit stronger and electrons would be pulled
in tighter.
2303.94 -> Weaken it and electrons could fly off on their
own like stars flung from out of a distant
2308.15 -> galaxy rendering them forever out of our atomonauts'
reach. Or you could weaken the strong nuclear
2314 -> force. Then protons and neutrons wouldn't
hug each other so tightly, increasing the
2318.79 -> size of the nucleus and hastening the electrons'
demise.
2323.68 -> A physicist would say that these forces appear
'finely tuned'. The dials have to be in pretty
2330.34 -> exact locations otherwise atoms wouldn't exist.
And one of the first people to discuss this
2337.56 -> so-called fine tuning in detail?
None other than Robert Dicke back in 1961.
2349.6 -> Electron orbits are far from the only aspects
of the atom that appear finely tuned. The
2353.7 -> neutron is a mere whisker heavier than the
proton, by about one seventh of one per cent.
2359.819 -> Physicists know this thanks to increasingly
precise experiments - indeed, in 2021 a pair
2364.849 -> of researchers from Florida State University
measured the deuteron to proton mass ratio
2370.14 -> to an accuracy of 4.5 parts in a trillion.
The small difference in mass between the neutron
2376.71 -> and the proton is greater than the mass of
the electron. And this is key. Were the electron
2383.85 -> heavier than the difference in mass between
its two bulkier cousins, it could be captured
2388.21 -> by a proton and turned into a neutron. In
other words, you can't change the masses of
2393.48 -> electrons, protons or neutrons by much either
or again atoms simply wouldn't exist.
2399.58 -> Fiddle with the control panel further and
you can cause more mayhem. The reason the
2403.48 -> neutron is heavier than the proton is due
to differences in the masses of their quarks.
2408.47 -> As we saw earlier, a proton is made of two
up quarks and one down quark. Two downs and
2413.78 -> one up form a neutron. The down quark is ever
so slightly more massive than the up quark,
2418.3 -> so a neutron is heavier than a proton. Yet
these masses appear finely tuned, too.
2424.64 -> If the difference in mass between down and
up quark were larger, the entire history of
2428.76 -> the universe would have been radically different.
A down quark would be able to decay into an
2433.7 -> up quark. If that happened inside a neutron,
suddenly the neutron would become a proton.
2439.71 -> The deuteron – that key marriage of a proton
to a neutron – would be annulled. That means
2444.88 -> no fusion after the Big Bang and a universe
that only contains atoms of hydrogen. None
2450.68 -> of the 117 other types of atom – or elements
- in the Periodic Table would exist. No oxygen
2458.08 -> for you to breathe or iron to carry that oxygen
around your body.
2463.16 -> Changing the mass of the quarks isn't the
only way to snuff out deuterons. They only
2467.43 -> exist because the strong nuclear force can
bind a proton to a neutron in the first place.
2472.339 -> Make that force just nine per cent weaker
and it would be too puny to hold deuterons
2476.8 -> together.
Going the other way - ratcheting up the strong
2479.89 -> force by just two per cent - would have even
more profound consequences. It would then
2485.49 -> be strong enough to bind two protons together–
a form of hydrogen called a diproton. We've
2491.56 -> never seen one in the real universe and there
have only been tantalising and unconfirmed
2496.04 -> reports of one inside experiments such as
the Radioactive Isotope Beam Factory in Japan.
2502.33 -> Had they existed after the Big Bang, they
would have rapidly fused into helium and all
2506.97 -> hydrogen would have quickly disappeared from
the universe. We'd live in a helium-dominated
2512.43 -> universe instead of a hydrogen-dominated one.
2519.652 -> And so, whichever dial, switch or knob we
2522.42 -> contemplate on the great control panel of
the universe, it is surprisingly easy to eradicate
2528.79 -> atoms.
In other words, all the settings appear to
2532.79 -> be in exactly the right place to permit atoms
– and the things they are built from - to
2538.73 -> exist.
It seems quite the coincidence.
2541.619 -> It's as baffling and unlikely as your survival
in front of the firing squad.
2548.73 -> And so physicists and philosophers have put
forward three broad ideas to explain this
2555.18 -> fine-tuning problem.
Maybe it's just dumb luck. After all, the
2561.859 -> settings all have to be somewhere and – although
almost impossible – they could all have
2566.01 -> fallen in the right place so as to give rise
to the first atom some 380,000 years after
2571.329 -> the Big Bang. By one account the odds are
about one in 65 billion trillion. That's roughly
2578.069 -> the same odds for you selecting the Sun when
asked to choose randomly from a bag containing
2582.859 -> all the stars in the observable universe.
Many find these odds too extreme to accept
2589.04 -> and see this apparent fine-tuning as evidence
of someone or something with a steady hand
2595.359 -> on the tiller. In other words, it was not
an accident but the deliberate act of manually
2600.96 -> setting the dials to the right places. This
could be some omnipotent deity or a bored
2606.95 -> advanced civilisation who wanted to create
their own real-life version of The Sims.
2613.04 -> There is another option, though. Thanks to
strands of evidence like the Cosmic Microwave
2621.14 -> Background, cosmologists are confident that
the universe began with something like a Big
2626.059 -> Bang. But what banged exactly? When trying
to answer that question, a tantalising possibility
2633.19 -> emerges.
The Big Bang is a good theory, but not a perfect
2639.089 -> one. Some scientists believe the cracks can
be papered over - and the theory salvaged
2643.799 -> - if there was more than one Bang. Perhaps
an infinity of Bangs, each one giving rise
2650.31 -> to a new universe. The settings on the control
panel of each universe could vary depending
2656.329 -> on the exact way that universe emerged from
the cacophony. All possible settings would
2661.559 -> be found across this endlessly large multiverse.
And which of those universes are you going
2669.48 -> to find yourself in? You can't be in ones
in which the dials are set so as not to permit
2674.73 -> atoms and in turn the stars and planets made
from them. You – a giant lump of atoms – can
2681.19 -> only find yourself in a universe where the
strengths of the fundamental forces and the
2686.53 -> masses of the sub-atomic particles allow atoms
to form.
2693.71 -> And what a journey those unlikely atoms have
been on. Their constituent parts forming within
2700.14 -> minutes of the Big Bang, to coalesce at recombination,
before hurtling across space, spinning into
2707.01 -> stars, exploding back into space, pulled into
planets, eventually ending up inside a brain
2713.44 -> capable of contemplating its place in this
vast and intricate universe.
Source: https://www.youtube.com/watch?v=ae36scLdCsE