How we explore unanswered questions in physics
-
0:01 - 0:05There is something about physics
-
0:05 - 0:09that has been really bothering me
since I was a little kid. -
0:11 - 0:13And it's related to a question
-
0:13 - 0:16that scientists have been asking
for almost 100 years, -
0:16 - 0:17with no answer.
-
0:19 - 0:22How do the smallest things in nature,
-
0:22 - 0:24the particles of the quantum world,
-
0:24 - 0:27match up with the largest
things in nature -- -
0:27 - 0:31planets and stars and galaxies
held together by gravity? -
0:31 - 0:34As a kid, I would puzzle
over questions just like this. -
0:34 - 0:37I would fiddle around
with microscopes and electromagnets, -
0:37 - 0:39and I would read
about the forces of the small -
0:39 - 0:41and about quantum mechanics
-
0:41 - 0:44and I would marvel at how well
that description matched up -
0:44 - 0:45to our observation.
-
0:46 - 0:48Then I would look at the stars,
-
0:48 - 0:50and I would read about how well
we understand gravity, -
0:50 - 0:54and I would think surely,
there must be some elegant way -
0:54 - 0:56that these two systems match up.
-
0:57 - 0:58But there's not.
-
1:00 - 1:01And the books would say,
-
1:01 - 1:04yeah, we understand a lot
about these two realms separately, -
1:04 - 1:07but when we try to link
them mathematically, -
1:07 - 1:08everything breaks.
-
1:09 - 1:10And for 100 years,
-
1:10 - 1:15none of our ideas as to how to solve
this basically physics disaster, -
1:15 - 1:17has ever been supported by evidence.
-
1:18 - 1:20And to little old me --
-
1:20 - 1:22little, curious, skeptical James --
-
1:22 - 1:25this was a supremely unsatisfying answer.
-
1:26 - 1:28So, I'm still a skeptical little kid.
-
1:28 - 1:32Flash-forward now
to December of 2015, -
1:33 - 1:36when I found myself smack in the middle
-
1:36 - 1:38of the physics world
being flipped on its head. -
1:40 - 1:43It all started when we at CERN
saw something intriguing in our data: -
1:43 - 1:46a hint of a new particle,
-
1:46 - 1:50an inkling of a possibly extraordinary
answer to this question. -
1:52 - 1:54So I'm still a skeptical
little kid, I think, -
1:54 - 1:56but I'm also now a particle hunter.
-
1:56 - 2:00I am a physicist at CERN's
Large Hadron Collider, -
2:00 - 2:03the largest science
experiment ever mounted. -
2:04 - 2:07It's a 27-kilometer tunnel
on the border of France and Switzerland -
2:07 - 2:09buried 100 meters underground.
-
2:09 - 2:10And in this tunnel,
-
2:10 - 2:14we use superconducting magnets
colder than outer space -
2:14 - 2:18to accelerate protons
to almost the speed of light -
2:18 - 2:21and slam them into each other
millions of times per second, -
2:21 - 2:24collecting the debris of these collisions
-
2:24 - 2:28to search for new, undiscovered
fundamental particles. -
2:29 - 2:31Its design and construction
took decades of work -
2:31 - 2:34by thousands of physicists
from around the globe, -
2:34 - 2:37and in the summer of 2015,
-
2:37 - 2:40we had been working tirelessly
to switch on the LHC -
2:40 - 2:45at the highest energy that humans
have ever used in a collider experiment. -
2:46 - 2:48Now, higher energy is important
-
2:48 - 2:50because for particles,
there is an equivalence -
2:50 - 2:53between energy and particle mass,
-
2:53 - 2:55and mass is just a number
put there by nature. -
2:56 - 2:57To discover new particles,
-
2:57 - 3:00we need to reach these bigger numbers.
-
3:00 - 3:03And to do that, we have to build
a bigger, higher energy collider, -
3:03 - 3:05and the biggest, highest
energy collider in the world -
3:05 - 3:07is the Large Hadron Collider.
-
3:08 - 3:13And then, we collide protons
quadrillions of times, -
3:13 - 3:17and we collect this data very slowly,
over months and months. -
3:19 - 3:23And then new particles might show up
in our data as bumps -- -
3:23 - 3:26slight deviations from what you expect,
-
3:26 - 3:30little clusters of data points
that make a smooth line not so smooth. -
3:30 - 3:32For example, this bump,
-
3:33 - 3:36after months of data-taking in 2012,
-
3:36 - 3:38led to the discovery
of the Higgs particle -- -
3:38 - 3:39the Higgs boson --
-
3:39 - 3:42and to a Nobel Prize
for the confirmation of its existence. -
3:44 - 3:48This jump up in energy in 2015
-
3:49 - 3:52represented the best chance
that we as a species had ever had -
3:52 - 3:53of discovering new particles --
-
3:53 - 3:56new answers to these
long-standing questions, -
3:56 - 3:59because it was almost
twice as much energy as we used -
3:59 - 4:01when we discovered the Higgs boson.
-
4:01 - 4:04Many of my colleagues had been working
their entire careers for this moment, -
4:04 - 4:06and frankly, to little curious me,
-
4:07 - 4:09this was the moment
I'd been waiting for my entire life. -
4:09 - 4:11So 2015 was go time.
-
4:13 - 4:15So June 2015,
-
4:16 - 4:18the LHC is switched back on.
-
4:19 - 4:22My colleagues and I held our breath
and bit our fingernails, -
4:22 - 4:24and then finally we saw
the first proton collisions -
4:24 - 4:26at this highest energy ever.
-
4:26 - 4:29Applause, champagne, celebration.
-
4:29 - 4:32This was a milestone for science,
-
4:32 - 4:37and we had no idea what we would find
in this brand-new data. -
4:40 - 4:42And then a few weeks later,
we found a bump. -
4:44 - 4:46It wasn't a very big bump,
-
4:47 - 4:49but it was big enough to make
you raise your eyebrow. -
4:49 - 4:52But on a scale of one to 10
for eyebrow raises, -
4:52 - 4:54if 10 indicates that you've
discovered a new particle, -
4:54 - 4:56this eyebrow raise is about a four.
-
4:56 - 4:57(Laughter)
-
4:58 - 5:04I spent hours, days, weeks
in secret meetings, -
5:04 - 5:06arguing with my colleagues
over this little bump, -
5:06 - 5:09poking and prodding it with our most
ruthless experimental sticks -
5:09 - 5:11to see if it would withstand scrutiny.
-
5:12 - 5:15But even after months
of working feverishly -- -
5:15 - 5:18sleeping in our offices
and not going home, -
5:18 - 5:20candy bars for dinner,
-
5:20 - 5:22coffee by the bucketful --
-
5:22 - 5:26physicists are machines
for turning coffee into diagrams -- -
5:26 - 5:27(Laughter)
-
5:27 - 5:30This little bump would not go away.
-
5:31 - 5:33So after a few months,
-
5:33 - 5:37we presented our little bump to the world
with a very clear message: -
5:37 - 5:40this little bump is interesting
but it's not definitive, -
5:40 - 5:44so let's keep an eye on it
as we take more data. -
5:44 - 5:46So we were trying to be
extremely cool about it. -
5:47 - 5:50And the world ran with it anyway.
-
5:50 - 5:52The news loved it.
-
5:53 - 5:55People said it reminded
them of the little bump -
5:55 - 5:59that was shown on the way
toward the Higgs boson discovery. -
5:59 - 6:02Better than that,
my theorist colleagues -- -
6:03 - 6:05I love my theorist colleagues --
-
6:05 - 6:09my theorist colleagues wrote
500 papers about this little bump. -
6:09 - 6:10(Laughter)
-
6:11 - 6:15The world of particle physics
had been flipped on its head. -
6:16 - 6:20But what was it about this particular bump
-
6:20 - 6:24that caused thousands of physicists
to collectively lose their cool? -
6:26 - 6:27This little bump was unique.
-
6:28 - 6:30This little bump indicated
-
6:30 - 6:33that we were seeing an unexpectedly
large number of collisions -
6:33 - 6:36whose debris consisted
of only two photons, -
6:36 - 6:37two particles of light.
-
6:37 - 6:38And that's rare.
-
6:39 - 6:42Particle collisions are not
like automobile collisions. -
6:42 - 6:43They have different rules.
-
6:43 - 6:46When two particles collide
at almost the speed of light, -
6:46 - 6:47the quantum world takes over.
-
6:47 - 6:49And in the quantum world,
-
6:49 - 6:52these two particles
can briefly create a new particle -
6:52 - 6:55that lives for a tiny fraction of a second
-
6:55 - 6:58before splitting into other particles
that hit our detector. -
6:58 - 7:01Imagine a car collision
where the two cars vanish upon impact, -
7:01 - 7:03a bicycle appears in their place --
-
7:03 - 7:04(Laughter)
-
7:04 - 7:07And then that bicycle explodes
into two skateboards, -
7:07 - 7:08which hit our detector.
-
7:08 - 7:09(Laughter)
-
7:09 - 7:11Hopefully, not literally.
-
7:11 - 7:13They're very expensive.
-
7:14 - 7:18Events where only two photons
hit out detector are very rare. -
7:18 - 7:22And because of the special
quantum properties of photons, -
7:22 - 7:25there's a very small number
of possible new particles -- -
7:26 - 7:27these mythical bicycles --
-
7:27 - 7:29that can give birth to only two photons.
-
7:30 - 7:33But one of these options is huge,
-
7:33 - 7:36and it has to do with
that long-standing question -
7:36 - 7:38that bothered me as a tiny little kid,
-
7:38 - 7:39about gravity.
-
7:42 - 7:45Gravity may seem super strong to you,
-
7:45 - 7:49but it's actually crazily weak
compared to the other forces of nature. -
7:49 - 7:51I can briefly beat gravity when I jump,
-
7:52 - 7:55but I can't pick a proton out of my hand.
-
7:56 - 8:00The strength of gravity compared
to the other forces of nature? -
8:00 - 8:03It's 10 to the minus 39.
-
8:03 - 8:05That's a decimal with 39 zeros after it.
-
8:05 - 8:06Worse than that,
-
8:06 - 8:09all of the other known forces of nature
are perfectly described -
8:09 - 8:12by this thing we call the Standard Model,
-
8:12 - 8:15which is our current best description
of nature at its smallest scales, -
8:15 - 8:16and quite frankly,
-
8:16 - 8:20one of the most successful
achievements of humankind -- -
8:20 - 8:24except for gravity, which is absent
from the Standard Model. -
8:24 - 8:26It's crazy.
-
8:26 - 8:29It's almost as though most
of gravity has gone missing. -
8:30 - 8:32We feel a little bit of it,
-
8:32 - 8:34but where's the rest of it?
-
8:34 - 8:35No one knows.
-
8:36 - 8:40But one theoretical explanation
proposes a wild solution. -
8:42 - 8:43You and I --
-
8:43 - 8:45even you in the back --
-
8:45 - 8:47we live in three dimensions of space.
-
8:47 - 8:50I hope that's a
non-controversial statement. -
8:50 - 8:52(Laughter)
-
8:52 - 8:55All of the known particles also live
in three dimensions of space. -
8:55 - 8:57In fact, a particle is just another name
-
8:57 - 9:00for an excitation
in a three-dimensional field; -
9:00 - 9:02a localized wobbling in space.
-
9:03 - 9:07More importantly, all the math
that we use to describe all this stuff -
9:07 - 9:10assumes that there are only
three dimensions of space. -
9:10 - 9:13But math is math, and we can play
around with our math however we want. -
9:13 - 9:17And people have been playing around
with extra dimensions of space -
9:17 - 9:18for a very long time,
-
9:18 - 9:20but it's always been an abstract
mathematical concept. -
9:20 - 9:23I mean, just look around you --
you at the back, look around -- -
9:24 - 9:26there's clearly only
three dimensions of space. -
9:27 - 9:29But what if that's not true?
-
9:30 - 9:36What if the missing gravity is leaking
into an extra-spatial dimension -
9:36 - 9:38that's invisible to you and I?
-
9:39 - 9:42What if gravity is just as strong
as the other forces -
9:42 - 9:46if you were to view it in this
extra-spatial dimension, -
9:46 - 9:49and what you and I experience
is a tiny slice of gravity -
9:49 - 9:50make it seem very weak?
-
9:52 - 9:53If this were true,
-
9:53 - 9:56we would have to expand
our Standard Model of particles -
9:56 - 10:00to include an extra particle,
a hyperdimensional particle of gravity, -
10:00 - 10:03a special graviton that lives
in extra-spatial dimensions. -
10:03 - 10:05I see the looks on your faces.
-
10:05 - 10:07You should be asking me the question,
-
10:07 - 10:10"How in the world are we going to test
this crazy, science fiction idea, -
10:10 - 10:13stuck as we are in three dimensions?"
-
10:13 - 10:14The way we always do,
-
10:14 - 10:16by slamming together two protons --
-
10:16 - 10:17(Laughter)
-
10:17 - 10:20Hard enough that
the collision reverberates -
10:20 - 10:23into any extra-spatial dimensions
that might be there, -
10:23 - 10:25momentarily creating
this hyperdimensional graviton -
10:25 - 10:30that then snaps back
into the three dimensions of the LHC -
10:30 - 10:32and spits off two photons,
-
10:32 - 10:34two particles of light.
-
10:35 - 10:38And this hypothetical,
extra-dimensional graviton -
10:38 - 10:42is one of the only possible,
hypothetical new particles -
10:42 - 10:44that has the special quantum properties
-
10:44 - 10:48that could give birth to our little,
two-photon bump. -
10:50 - 10:56So, the possibility of explaining
the mysteries of gravity -
10:56 - 10:59and of discovering extra
dimensions of space -- -
10:59 - 11:01perhaps now you get a sense
-
11:01 - 11:05as to why thousands of physics geeks
collectively lost their cool -
11:05 - 11:07over our little, two-photon bump.
-
11:07 - 11:10A discovery of this type
would rewrite the textbooks. -
11:11 - 11:12But remember,
-
11:12 - 11:14the message from us experimentalists
-
11:14 - 11:16that actually were doing
this work at the time, -
11:16 - 11:17was very clear:
-
11:17 - 11:18we need more data.
-
11:18 - 11:20With more data,
-
11:20 - 11:24the little bump will either turn into
a nice, crisp Nobel Prize -- -
11:24 - 11:26(Laughter)
-
11:26 - 11:29Or the extra data will fill in
the space around the bump -
11:29 - 11:31and turn it into a nice, smooth line.
-
11:32 - 11:33So we took more data,
-
11:33 - 11:35and with five times the data,
several months later, -
11:35 - 11:37our little bump
-
11:37 - 11:39turned into a smooth line.
-
11:43 - 11:47The news reported on a "huge
disappointment," on "faded hopes," -
11:47 - 11:49and on particle physicists "being sad."
-
11:49 - 11:51Given the tone of the coverage,
-
11:51 - 11:55you'd think that we had decided
to shut down the LHC and go home. -
11:55 - 11:56(Laughter)
-
11:57 - 11:58But that's not what we did.
-
12:01 - 12:03But why not?
-
12:04 - 12:07I mean, if I didn't discover
a particle -- and I didn't -- -
12:08 - 12:11if I didn't discover a particle,
why am I here talking to you? -
12:11 - 12:14Why didn't I just hang my head in shame
-
12:14 - 12:15and go home?
-
12:19 - 12:23Particle physicists are explorers.
-
12:23 - 12:26And very much of what we do
is cartography. -
12:27 - 12:30Let me put it this way: forget
about the LHC for a second. -
12:30 - 12:34Imagine you are a space explorer
arriving at a distant planet, -
12:34 - 12:35searching for aliens.
-
12:35 - 12:37What is your first task?
-
12:38 - 12:41To immediately orbit the planet,
land, take a quick look around -
12:41 - 12:43for any big, obvious signs of life,
-
12:43 - 12:45and report back to home base.
-
12:45 - 12:46That's the stage we're at now.
-
12:47 - 12:49We took a first look at the LHC
-
12:49 - 12:51for any new, big,
obvious-to-spot particles, -
12:51 - 12:53and we can report that there are none.
-
12:54 - 12:56We saw a weird-looking alien bump
on a distant mountain, -
12:56 - 12:58but once we got closer,
we saw it was a rock. -
12:59 - 13:01But then what do we do?
Do we just give up and fly away? -
13:01 - 13:03Absolutely not;
-
13:03 - 13:05we would be terrible scientists if we did.
-
13:05 - 13:09No, we spend the next couple
of decades exploring, -
13:09 - 13:10mapping out the territory,
-
13:10 - 13:13sifting through the sand
with a fine instrument, -
13:13 - 13:14peeking under every stone,
-
13:14 - 13:16drilling under the surface.
-
13:16 - 13:19New particles can either
show up immediately -
13:19 - 13:21as big, obvious-to-spot bumps,
-
13:21 - 13:25or they can only reveal themselves
after years of data taking. -
13:26 - 13:31Humanity has just begun its exploration
at the LHC at this big high energy, -
13:31 - 13:32and we have much searching to do.
-
13:32 - 13:38But what if, even after 10 or 20 years,
we still find no new particles? -
13:39 - 13:41We build a bigger machine.
-
13:41 - 13:42(Laughter)
-
13:42 - 13:44We search at higher energies.
-
13:44 - 13:46We search at higher energies.
-
13:47 - 13:50Planning is already underway
for a 100-kilometer tunnel -
13:51 - 13:54that will collide particles
at 10 times the energy of the LHC. -
13:54 - 13:56We don't decide where
nature places new particles. -
13:56 - 13:58We only decide to keep exploring.
-
13:58 - 14:01But what if, even after
a 100-kilometer tunnel -
14:01 - 14:02or a 500-kilometer tunnel
-
14:03 - 14:05or a 10,000-kilometer
collider floating in space -
14:05 - 14:07between the Earth and the Moon,
-
14:07 - 14:10we still find no new particles?
-
14:12 - 14:14Then perhaps we're doing
particle physics wrong. -
14:14 - 14:16(Laughter)
-
14:16 - 14:18Perhaps we need to rethink things.
-
14:19 - 14:22Maybe we need more resources,
technology, expertise -
14:22 - 14:24than what we currently have.
-
14:25 - 14:28We already use artificial intelligence
and machine learning techniques -
14:28 - 14:29in parts of the LHC,
-
14:29 - 14:32but imagine designing
a particle physics experiment -
14:32 - 14:33using such sophisticated algorithms
-
14:33 - 14:36that it could teach itself to discover
a hyperdimensional graviton. -
14:36 - 14:38But what if?
-
14:38 - 14:39What if the ultimate question:
-
14:39 - 14:43What if even artificial intelligence
can't help us answer our questions? -
14:43 - 14:45What if these open questions,
for centuries, -
14:45 - 14:47are destined to be unanswered
for the foreseeable future? -
14:47 - 14:50What if the stuff that's bothered me
since I was a little kid -
14:50 - 14:53is destined to be unanswered
in my lifetime? -
14:54 - 14:56Then that ...
-
14:56 - 14:58will be even more fascinating.
-
15:00 - 15:03We will be forced to think
in completely new ways. -
15:04 - 15:06We'll have to go back to our assumptions,
-
15:06 - 15:09and determine if there was
a flaw somewhere. -
15:09 - 15:13And we'll need to encourage more people
to join us in studying science -
15:13 - 15:16since we need fresh eyes
on these century-old problems. -
15:16 - 15:19I don't have the answers,
and I'm still searching for them. -
15:19 - 15:21But someone -- maybe
she's in school right now, -
15:21 - 15:23maybe she's not even born yet --
-
15:24 - 15:27could eventually guide us to see physics
in a completely new way, -
15:27 - 15:31and to point out that perhaps
we're just asking the wrong questions. -
15:32 - 15:35Which would not be the end of physics,
-
15:35 - 15:36but a novel beginning.
-
15:37 - 15:38Thank you.
-
15:38 - 15:41(Applause)
- Title:
- How we explore unanswered questions in physics
- Speaker:
- James Beacham
- Description:
-
James Beacham looks for answers to the most important open questions of physics using the biggest science experiment ever mounted, CERN's Large Hadron Collider. In this fun and accessible talk about how science happens, Beacham takes us on a journey through extra-spatial dimensions in search of undiscovered fundamental particles (and an explanation for the mysteries of gravity) and details the drive to keep exploring.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 15:54
Brian Greene edited English subtitles for How we explore unanswered questions in physics | ||
Brian Greene edited English subtitles for How we explore unanswered questions in physics | ||
Brian Greene approved English subtitles for How we explore unanswered questions in physics | ||
Brian Greene edited English subtitles for How we explore unanswered questions in physics | ||
Camille Martínez accepted English subtitles for How we explore unanswered questions in physics | ||
Camille Martínez edited English subtitles for How we explore unanswered questions in physics | ||
Camille Martínez edited English subtitles for How we explore unanswered questions in physics | ||
Leslie Gauthier edited English subtitles for How we explore unanswered questions in physics |