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Welcome to another installment of our LBS physics deep dive! After exploring the world of experimental physics at CERN in our first video documentary in episode 93, we’ll stay in Geneva for this one, but this time we’ll dive into theoretical physics.
We’ll explore mysterious components of the universe, like dark matter and dark energy. We’ll also see how the study of gravity intersects with the study of particle physics, especially when considering black holes and the early universe. Even crazier, we’ll see that there are actual experiments and observational projects going on to answer these fundamental questions!
Our guide for this episode is Valerie Domcke, permanent research staff member at CERN, who did her PhD in Hamburg, Germany, and postdocs in Trieste and Paris.
When she’s not trying to decipher the mysteries of the universe, Valerie can be found on boats, as she’s a big sailing fan.
Our theme music is « Good Bayesian », by Baba Brinkman (feat MC Lars and Mega Ran). Check out his awesome work at https://bababrinkman.com/ !
Thank you to my Patrons for making this episode possible!
Yusuke Saito, Avi Bryant, Ero Carrera, Giuliano Cruz, Tim Gasser, James Wade, Tradd Salvo, William Benton, James Ahloy, Robin Taylor,, Chad Scherrer, Zwelithini Tunyiswa, Bertrand Wilden, James Thompson, Stephen Oates, Gian Luca Di Tanna, Jack Wells, Matthew Maldonado, Ian Costley, Ally Salim, Larry Gill, Ian Moran, Paul Oreto, Colin Caprani, Colin Carroll, Nathaniel Burbank, Michael Osthege, Rémi Louf, Clive Edelsten, Henri Wallen, Hugo Botha, Vinh Nguyen, Marcin Elantkowski, Adam C. Smith, Will Kurt, Andrew Moskowitz, Hector Munoz, Marco Gorelli, Simon Kessell, Bradley Rode, Patrick Kelley, Rick Anderson, Casper de Bruin, Philippe Labonde, Michael Hankin, Cameron Smith, Tomáš Frýda, Ryan Wesslen, Andreas Netti, Riley King, Yoshiyuki Hamajima, Sven De Maeyer, Michael DeCrescenzo, Fergal M, Mason Yahr, Naoya Kanai, Steven Rowland, Aubrey Clayton, Jeannine Sue, Omri Har Shemesh, Scott Anthony Robson, Robert Yolken, Or Duek, Pavel Dusek, Paul Cox, Andreas Kröpelin, Raphaël R, Nicolas Rode, Gabriel Stechschulte, Arkady, Kurt TeKolste, Gergely Juhasz, Marcus Nölke, Maggi Mackintosh, Grant Pezzolesi, Avram Aelony, Joshua Meehl, Javier Sabio, Kristian Higgins, Alex Jones, Gregorio Aguilar, Matt Rosinski, Bart Trudeau, Luis Fonseca, Dante Gates, Matt Niccolls and Maksim Kuznecov.
Visit https://www.patreon.com/learnbayesstats to unlock exclusive Bayesian swag 😉
Links from the show:
- Valerie’s webpage: https://theory.cern/roster/domcke-valerie
- Valerie on Google Scholar: https://scholar.google.com/citations?user=E3g0tn4AAAAJ
- LBS #93 A CERN Odyssey, with Kevin Greiff: https://www.youtube.com/watch?v=rOaqIIEtdpI
- LBS #64, Modeling the Climate & Gravity Waves, with Laura Mansfield: https://learnbayesstats.com/episode/64-modeling-climate-gravity-waves-laura-mansfield/
- LBS Physics Playlist: https://learnbayesstats.com/physics-astrophysics/
Abstract
Episode 95 is another instalment of our Deep Dive into Physics series. And this time we move away from the empirical side of this topic towards more theoretical questions.
There is no one better for this topic than Dr. Valerie Domcke. Valerie is the second researcher from the CERN we have on our show. She is located at the Department of Theoretical Physics there.
We mainly focus on the Standard Model of Physics, where it fails to explain observations, what proposals are discussed to update or replace it and what kind of evidence would be needed to make such a decision.
Valerie is particularly interested in situations in which the Standard Model brakes down, such as when trying to explain the excess gravitational pull observed that cannot be accounted for by visible stars.
Of course, we cover fascinating topics like dark matter, dark energy, black holes and gravitational waves that are places to look for evidence against the Standard Model.
Looking more at the practical side of things, we discuss the challenges in disentangling signal from noise, especially in such complex fields as astro- and quantum-physics.
We also touch upon the challenges Valerie is currently tackling in working on a new observatory for gravitational waves, the Laser Interferometer Space Antenna, LISA.
Transcript
This is an automatic transcript and may therefore contain errors. Please get in touch if you’re willing to correct them.
Transcript
Welcome to another installment of our LBS
physics deep dive.
2
After exploring the world of experimental
physics at CERN in our first video
3
documentary in episode 93, we'll stay in
Geneva for this one, but this time we'll
4
dive into theoretical physics.
5
We'll explore mysterious components of the
universe, like dark matter and dark
6
energy.
7
We'll also see how the study of gravity
intersects.
8
with the study of particle physics,
especially when considering black holes
9
and the early universe.
10
Even crazier, we'll see that there are
actual experiments and observational
11
projects going on to answer these
fundamental questions.
12
Our guide for this episode is Valérie
Dormcke, permanent research staff member
13
at CERN who did her PhD in Hamburg,
Germany, and postdocs in Trieste and
14
Paris.
15
When she's not trying to decipher the
mysteries of the universe, Valérie can be
16
found on
17
she's a big sailing fan.
18
This is Learning Vagin Statistics, episode
95, recorded September 6, 2023.
19
Hello my dear Vagins!
20
Some of you have reached out for advice
and coaching in parallel to my online
21
courses on intuitivevagin.com.
22
So, to help you, I have started something
new.
23
If you go to
24
You can pair your online course with my
15-hour or 20-hour coaching packages to
25
get a fully premium learning path.
26
Each week, we'll get on a one-to-one call
and we'll walk through any questions,
27
difficulties, or roadblocks that you may
have to jumpstart your learning even more.
28
Again, that's topmate.io slash Alex
underscore and Dora.
29
And now, let's talk theoretical physics
with Valerie Donka.
30
I'll show you how to be a good peasy and
change your predictions.
31
Valérie Damke, welcome to Learning Asian
Statistics.
32
Glad to be here.
33
Yeah.
34
Thank you for taking the time.
35
I am really happy to have you on the show.
36
Again, a physics-packed episode.
37
I'm really, really happy about that and I
have a lot of questions for you.
38
I think you're the first theoretical
physicist to come on the show.
39
That's cool.
40
We're going to talk about topics.
41
a bit different than those we talk about
when we have experimental physicists on
42
the show.
43
So that's cool, more diversity for the
listeners.
44
And also, when that episode is going to
air, by the magic of time travel, episode
45
93 will have been published.
46
So that's the one at CERN.
47
So the very special video documentary I
did at CERN with Kevin Kaif.
48
So if listeners haven't checked it out
yet, I highly recommend it.
49
And that one, of course, I recommend
mainly watching the YouTube video because
50
I recorded and edited it firstly for video
format.
51
You have access to the audio format also,
but I'm telling you, it's going to be
52
funnier in video.
53
So now to actually complete what we talked
about in episode 93.
54
where Kevin does a lot of fun experiments
at CERN, today we are going to talk about
55
another part of physics that's done at
CERN, thanks to you, Valerie.
56
But first, before doing that, let's start
with your origin story.
57
How did you come to the world of
theoretical physics, and how sinuous of a
58
path was it?
59
It was, it was more of a path that I kind
of ended up on without honestly thinking
60
about it too much.
61
It's kind of been a topic that has
fascinated me since I was quite young,
62
reading science fiction books and the
like.
63
And I basically, we just kind of following
my interests, taking the course of the
64
university that interests me most without
thinking too much about where that would
65
lead me in the end.
66
And it was basically only when I was doing
my PhD that I realized, wow, I'm actually
67
working on cosmology and kind of these big
open questions of the universe, which is
68
something I was dreaming about as a kid.
69
And somehow I got there without, somehow
without too much planning, but just
70
following what I thought was kind of the
most interesting thing for me to do at
71
every step.
72
Oh yeah, so it's really like the call of
passion for you.
73
In a sense, in a sense.
74
Yeah, that's really cool.
75
I mean, and that's also one of the cool
things of this kind of job, right?
76
In physics or I don't know, airplane
pilots or firefighters.
77
You can dream about them already as you're
a kid and then make that your job.
78
I personally love my job, but...
79
I'm afraid I cannot say that I dreamed
about patient statistics when I was a kid.
80
Like I never told when I was five years
old, oh, I want to be a patient
81
statistician.
82
You know, that's not how it works,
unfortunately.
83
Really?
84
Yeah, no, I know, I know that must be
quite disappointing to a lot of people,
85
but I had to burst that bubble because I
get a lot of questions about that, yeah.
86
So.
87
I would also say that you kind of have to
really...
88
dream about or be enthusiastic about it,
because doing science, you always
89
encounter moments when nothing works.
90
Yeah.
91
And if you're not passionate about
actually solving the problem, it's, you're
92
just going to get stuck.
93
Yeah.
94
No, definitely.
95
That's a very good point.
96
And that's where actually statistics get
back in the, in the mix, because that's, I
97
would say that's the same for
98
programming and the kind of statistics at
least I do where you are going to get a
99
lot of bumps along the way.
100
And I always say to beginners that models
never work, only the last iteration of a
101
model is going to work.
102
And even then, you just have to be
satisfied with good enough.
103
So that's a field where you have to become
comfortable failing all the time.
104
First, be comfortable with making mistakes
and failing.
105
And also where you need to be driven by
passion because if you don't have that
106
inherent passion, you're not going to
still be driven to solve those numerous
107
data analysis issues and bugs and stuff
like that.
108
So now, I'd like to talk about what you do
actually, what you're doing nowadays,
109
because we know you dreamt about doing
that since you were a child.
110
But how would you define the work you're
doing nowadays and what are the topics
111
that you are particularly interested in?
112
Right, I think there's probably two parts
to that question, right?
113
One is kind of how does an everyday day
actually look like?
114
And the other one is, okay, what are the
big topics I'm interested in?
115
Yeah.
116
So to start with the format, so what my
day does not look like is that I kind of
117
sit in my office all by myself, waiting
for the fantastic idea that is going to
118
win me a Nobel Prize.
119
That's kind of the image I had maybe as a
kid of how a theoretical thesis would
120
work.
121
But that's not at all what my day looks
like.
122
Right.
123
So I'm it's a lot discussing with people,
listening to talks, going to conferences,
124
reading papers, discussing over coffee on
a blackboard over lunch.
125
And then progress comes bit by bit.
126
But it does kind of, there's never a lack
of things to work on.
127
There's never a lack of interesting
questions.
128
There's only always a lack of time to
decide what is the most interesting
129
question of all the questions to work on.
130
Because there's really a lot of things
that we don't understand.
131
And that brings me a bit to the
overarching team of my research.
132
So I work on the intersection of particle
physics and cosmology.
133
So
134
meaning kind of the physics of the very,
very smallest particles, the fundamental
135
building blocks of nature.
136
And at the same time, the physics of the
very largest scales, so the largest scales
137
we can observe in our universe, and how
the latter can teach us something about
138
the former.
139
So how kind of from astrophysical or
cosmological observations, we can learn
140
something about what is really the nature
of the fundamental building blocks of
141
nature.
142
Yeah, so small topics, fundamental
building blocks of nature.
143
Yeah, thanks.
144
That's interesting.
145
I'm actually curious.
146
So of course, we're going to talk about
the projects you work on a day to day a
147
bit more.
148
But also I'm curious now that you brought
up basically what your days look like
149
concretely.
150
Yeah.
151
What's the part of basically solitary work
with pen and paper?
152
What's the proportion of that in
comparison to, as you were saying,
153
collaboration with people, exchange of
ideas and things like that?
154
Because I think when you tell people
you're a theoretical physicist, and that's
155
definitely the case when you tell people
you're a statistician, most of the people
156
doing math on a blackboard.
157
So most of the time, which is not true if
you're a statistician.
158
So yeah, I'm curious how it is on your
slide.
159
Yeah, it's probably similar.
160
I mean, if I get one or two hours on block
to actually sit down and do a calculation,
161
that's rather the exception than the rule.
162
So it is, of course, part of my job, and I
enjoy it a lot.
163
Sometimes just to have time just to think.
164
really thoroughly about a problem, either
analytically, so pen and paper, or coding.
165
But it's usually not like very long
stretches at a time because then you
166
either you hit a problem, right?
167
Or you hit a solution.
168
And in either case, that's the point to
reach out to your collaborators and
169
discuss the next steps.
170
Yeah.
171
I mean, that's interesting because for me,
now I'm using more and more the
172
excuse of teaching to dive deep in a topic
and a project because, well, I have to be
173
able to explain it properly to students.
174
So that's actually, these are actually the
good occasions and rare, quite rare
175
occasions where I can just be myself
working on the computer or sometimes with
176
a pen and paper and really understand
deeply.
177
a topic that I need and want to understand
because otherwise, yeah, you have so many
178
other projects and solicitations that can
be hard to actually take the time just for
179
yourself and focus on these.
180
So I'm the same.
181
I do appreciate these solitary moments,
although I'm happy that they are not 90%
182
of the work, I have to say.
183
Yeah, same here.
184
And actually, Sue, you...
185
You're a very math savvy person.
186
So of course you know about patient stats,
but I'm curious if you were introduced to
187
Bayesian methods actually, you know, in
your graduate studies or before, and if
188
you use them from time to time in your own
work.
189
No, so I never received any.
190
any type of formal or informal training.
191
So it's, of course, it's something we need
to know in the sense that we deal with
192
empirical data.
193
Even if I myself don't usually deal
directly with the empirical data, but I
194
kind of deal with the processed empirical
data, or I deal with the publications that
195
people have written on the data, and then
I need to evaluate, interpret, and kind of
196
continue to work from there.
197
But for that, of course, I need to kind of
understand the significance of certain
198
experimental results.
199
So I would say, okay, I mean, I have a
fundamental understanding of them, right.
200
But it's, it's not something that actually
kind of on a on a day to day basis, I
201
really am like deep in the in the details
of it.
202
Yeah, because I'm more work at the kind of
one level.
203
away, right?
204
So kind of that I that I kind of take, I
need to understand what is the
205
significance of that result, right?
206
But once I've understood that, I can
basically work directly with the result
207
without having going to back to the data
at every step.
208
Which is quite a luxury, I have to say.
209
I'm a bit jealous.
210
I'm very, very happy that there's people
who do the work that I don't need to do.
211
Yeah, that's, that's a very good point.
212
I like that.
213
And if you go listen to episode 93, you'll
see the difference between basically that
214
kind of work that Valery does and the
experimental physics work where statistics
215
is way more present and of course, patient
statistics is extremely helpful.
216
So I find that super interesting to
notice.
217
Just because you don't use patient stats,
Valery doesn't mean that your work is not
218
interesting.
219
I have to put that out there.
220
On the contrary, I find it fascinating.
221
So let's dive in because one of your areas
of interest is to go beyond the standard
222
model phenomenology to kind of probe it,
if I understood correctly.
223
So can you tell us what that means and
maybe first define the standard model for
224
us?
225
Right.
226
So the standard model basically reflects
our current understanding of these
227
fundamental building blocks of nature.
228
So it kind of contains what we think are
kind of elementary particles, which are no
229
longer further dividable into even smaller
particles.
230
And there's not many of them.
231
There's basically a handful of them,
depending how you count.
232
And we think that these...
233
fundamental particles together with the
interactions between these particles that
234
they explain all of kind of nature, the
way it surrounds us, right?
235
So all, all everything that we can, we can
grasp, grasp or experience here on earth.
236
And the standard model describes basically
this.
237
So it describes kind of which building
blocks are there and how do they interact
238
with each other.
239
And now going beyond the standard model,
because a model is always a model, right?
240
So it means that it describes kind of
nature to the best of our knowledge.
241
But most models are incomplete at some
level, right?
242
Because because it's kind of only a way
that we describe nature, not actually the
243
fundamental theory of nature.
244
And for this, the standard model of
particle physics, in particular, it, it
245
does extremely well in many respects, one
could even say,
246
frustratingly well, because like in all
our searches of looking for new
247
interactions, looking for new particles
here at CERN at the Large Hadron Collider,
248
we always keep confirming the predictions
that the standard model makes with
249
incredible accuracy.
250
But we still know the model is not
complete.
251
And the reason we know that the model is
not complete basically comes from
252
cosmology.
253
So there's observations that we make about
the dynamics of the universe.
254
or properties of the universe, which are
simply in contradiction with this model,
255
which tells us that there's ingredients
missing.
256
And we have a rough idea of what these
ingredients are.
257
Or rather, maybe, instead of one rough
idea, we have 100 rough ideas.
258
And the big question is, which one of
these is correct?
259
Is any one of these correct?
260
And how can we make progress in
understanding these missing parts better?
261
So to give you some keywords, things like
dark energy, dark matter, those are some
262
of the open questions.
263
Yeah, because we know basically you say
they are open because first we cannot
264
really explain them fully for now, as we
said in episode 93, but also we know that
265
the standard model breaks down at those
points and cannot explain them.
266
So that's basically what you're trying to
understand.
267
Why does the standard model fail here and
how can we actually explain these
268
phenomena?
269
Correct.
270
I see.
271
So concretely, what does that research
look like?
272
Maybe could you share an example of a
discovery or theoretical development in
273
this field that has the potential to
reshape our understanding of particle
274
physics?
275
You mean like a discovery in the past that
did that or a discovery, potential
276
discovery in the future that...
277
I would say both.
278
Yeah, both if you can.
279
Let's start with the past.
280
So one observation, for example, was
rotation curves of galaxies.
281
So people were looking at galaxies in the
sky.
282
And they were they were looking at kind of
how fast the stars were rotating, which
283
you can do by measuring the redshift of
the stars.
284
Because as they move away from us, the
light gets slightly red as they move
285
towards us, the light gets slightly bluer.
286
And if you know, like if you have an
object on a stationary orbit, and you
287
know, you know, the orbit, you know, the
velocity.
288
I mean, actually, even knowing the orbit
and the mass of stars enough.
289
Then you can estimate how much mass you
need in a center in order to make that a
290
stable orbit.
291
And so that's just Newton dynamics, high
school physics.
292
And what people observed is that the mass
that you needed in the center in order to
293
put these stars on the orbits that were
being observed was much, much bigger than
294
the mass you would have inferred just by
counting stars.
295
And now you can say, OK, well, counting
stars is obviously not enough, right?
296
Because there's going to be planets.
297
Planets are not luminous.
298
So there's going to be a bit of an offset,
but you would have expected that counting
299
stars would give you a good estimate.
300
And it turned out it was completely off.
301
So it turned out it was kind of a big
amount of something that has an attractive
302
gravitational force in the center of the
galaxies, or like in a halo around the
303
galaxies, which was invisible to our
telescopes.
304
And that is basically what I'm coined the
term dark matter.
305
because it kind of has a gravitational
pull of matter, just like everything else.
306
But it's dark, meaning we can't see it.
307
And not seeing it means like not only kind
of we don't pick it up with telescopes,
308
but kind of also all other type of
experiment that we've performed to date,
309
trying to find this stuff.
310
And this stuff should be around
everywhere, right?
311
So it's not that there's none of it on
Earth.
312
It's just that it's so incredibly weakly
interacting with...
313
Yeah.
314
all the instruments that we build, that
it's very difficult to see.
315
And then observations, I mean, more
observations, particularly cosmological
316
observations, reveal that there's actually
five times more of this dark matter than
317
there is of what we call ordinary matter.
318
So ordinary matter is everything that we
know of on Earth and everything that we
319
can describe with our standard model of
part of the physics.
320
Meaning that there's really a lot of stuff
out there that we don't know.
321
That's just one example.
322
And that kind of gave very clear
indication that the Sonop model of
323
particle physics is incomplete.
324
And that we're not only missing a little
bit, but that we're actually missing a
325
very big bit of the picture.
326
And along the same line of thought, you
know, what would really be a
327
groundbreaking discovery if one of the
many experiments looking for such a dark
328
matter particle, if they would actually
find something.
329
I mean, even if they don't find anything,
if a particular experiment doesn't find
330
anything, then okay, you still learn
something because you can probably exclude
331
some class of models.
332
But if one of them actually made a
discovery, and we would have kind of a
333
very clear indication of which direction
to go in when we're kind of trying to
334
describe these dark matter particles, that
would be a complete game changer.
335
Yeah, for sure.
336
And so these kinds of experiments are
underway at CERN in particular, right?
337
Yeah, at CERN and across the world.
338
I mean, it's something you can look for
when in a collider because you can always
339
hope that as your collider reaches higher
and higher energy, or you have just more
340
and more particles that you're colliding,
you'll eventually kind of reach the
341
threshold for producing these particles.
342
And then you can find indirect traces of
them.
343
in the K channels, or you basically have
some sort of, not a collider, but
344
basically just a very big detector volume
somewhere.
345
So a very big amount of an noble gas, for
example, even water.
346
And then you wait basically for a dark,
you like have to shield it very well
347
against everything else.
348
And then you wait for some dark matter
particle.
349
to have one of these very rare
interactions with one of the atoms of your
350
detector.
351
And you're looking for that interaction.
352
And there's a there's a range of
experiments underway, looking for very
353
different types of these dark matter
candidates.
354
Yeah, so but we've been we've been hoping
that we'll find it any day now.
355
Basically, since I don't know, I mean,
basically, since I do physics.
356
So we don't know.
357
It could be around the corner or it could
be very well hidden.
358
Yeah.
359
I mean, these kinds of experiments, I
think I would not be able to work on them
360
at least full time, you know, that's
awful.
361
Like you're just waiting for something and
you cannot control anything.
362
Oh, there's plenty of stuff to do.
363
You're not just waiting, right?
364
I mean, because you're basically
constantly fighting to reduce noise,
365
reduce background, understand noise.
366
understand background, argue with somebody
who's making noise in the building next
367
door, right?
368
And disrupting your experiments.
369
So, Yeah, yeah, no, for sure.
370
That's, yeah, that's something you have to
deal with all the time, I guess.
371
But yeah, I mean, I would be also, you
know, incredibly stressed out.
372
Like, so did the, I think a lot of them
are helium pools, right?
373
Or something like that.
374
Did the helium pool move tonight or not?
375
I would be incredibly stressed out.
376
Yeah, so thanks a lot.
377
That's actually very interesting to hear
about that because I find this kind of
378
experiment absolutely fascinating.
379
And where does your work come into that
picture?
380
So you're part of these big teams, right,
in physics.
381
Like you see a physics paper, it's like
most of the time a lot of people, because
382
a lot of you are very, like many of you
are very specialized in what they do.
383
And so you bring one of the brick to the
paper.
384
So you in this kind of work, what do you
do?
385
What do you bring?
386
So the papers really with like the many
hundreds of authors, they're usually the
387
experimental collaborations.
388
So.
389
As a theorist, you know, I usually have
whatever, two, three, four, co-authors on
390
a paper.
391
That's a lot.
392
Right.
393
So we build, of course, very heavily on
the results of these big collaboration
394
papers.
395
But largely, the work that I concretely do
is with much smaller groups of people.
396
So, yeah, I basically have two...
397
two main approaches to this.
398
One is kind of starting from really
standard model of particle physics, and
399
trying to come up with possible extensions
of that, which kind of makes sense within
400
the framework that the standard model is
written in.
401
So it makes sense within the symmetries
that they are, makes sense within the
402
framework of quantum field theory, and
address some of these open problems that
403
we have in cosmology.
404
And then the question is, okay, once
you've kind of constructed
405
such an inherently consistent model, what
sort of implications might that have in
406
various types of experiments?
407
Right.
408
So that can be experiments like the chart
Hadron Collider.
409
It can also be some astrophysical
observations, or it can be some
410
cosmological observations.
411
So that's kind of one approach, and coming
kind of more from the fundamental
412
mathematical theory of it.
413
My other approach is more the lamppost
approach, meaning, well, you, you look
414
where you can look right, and you hope
that nature is kind.
415
And they're kind of the my approach is to
say, okay, what types of probes do we have
416
of the universe of astrophysical
processes?
417
Try and understand as much as possible
about those, and then see what type of
418
models or what kind of types of building
blocks of models.
419
you could test with these types of
observations.
420
And there, for example, the new big player
in the game are gravitational waves.
421
Because now since the first discovery with
LIGO and now a tentative discovery in a
422
different frequency range this year with
the pulse of timing arrays, that's kind of
423
opening up a completely new way of
observing our universe.
424
And so there's the potential for...
425
for big excitement in that field.
426
So I'm also just involved in trying to
understand as much as possible about how
427
gravitational waves can reveal something
about the universe.
428
Oh, yeah.
429
So that's actually fascinating.
430
So yeah, talk to us a bit more about that,
basically.
431
What can gravitational waves tell us about
the universe?
432
And maybe redefine quickly what
gravitational waves
433
waves are for listeners?
434
Right, so gravitational waves are, we
think of them as perturbations of the
435
metric, so perturbations of space-time.
436
So the type of gravitational waves that
we've already seen with LIGO and Virgo,
437
which are big Michelson interferometers,
so the type of
438
which are circling each other and then
finally merging.
439
So these are like extremely massive
objects.
440
And as you might know, a massive object
kind of creates if you want a dent in
441
space-time.
442
And if you have two of them, just kind of
their dance around each other really like
443
sends out ripples of this kind of
space-time perturbations out into the
444
universe.
445
If you're very close to a black hole,
right, these ripples will be quite
446
significant.
447
But then you'd also have all sorts of
other problems, right?
448
Because if you're really close to black
hole, I mean, then you have a lot of
449
problems.
450
So, by the time these gravitational waves
reach us, they've kind of spread out very
451
far, meaning the amplitude is very much
decreased.
452
So, by the time they reach us, these are
typically very, very small, like tiny
453
perturbations in space time.
454
So it's not something we have to worry
about in everyday life, rather we need to
455
build an extremely sensitive detector to
even pick them up.
456
And so, so far, the observations that
we've made are this type of observation.
457
So observations of these black holes
merging, which happened, I mean, still at
458
the distance of megaparsecs or gigaparsecs
from here, right?
459
So it kind of...
460
Yeah, quite far away on cosmological
scales.
461
But nevertheless, compared to the lifespan
of the universe, these are still fairly
462
recent events.
463
So at the moment, we're using this to
learn, as a new way to learn about the
464
universe surrounding us or the more recent
universe or the relatively recent
465
universe.
466
Because these gravitational waves are so
weakly interacting with everything, in
467
principle, even gravitational waves
generated in the very, very early
468
universe, when the universe was not yet
transparent to photons, when kind of no
469
other messenger could escape this
primordial soup.
470
Gravitational waves could.
471
So in principle, if we detected them
today, they could reveal information about
472
extremely early times in the universe,
when the temperatures in the universe were
473
extremely high, when all the fundamental
particles.
474
kind of existed as fundamental particles.
475
And when we can really kind of probe these
constituents of the standard model or of
476
any model beyond the standard model.
477
So that's the ultimate hope.
478
But it's challenging because we don't know
what is the amplitude of these gravitation
479
waves from the very early universe.
480
And so we first need to understand the
gravitation waves generated in the late
481
universe.
482
Make sure we fully understand that before
we kind of look for a fainter signal.
483
Very similar to with photons, right?
484
You basically first need to kind of
understand all the light kind of coming
485
from the nearby universe, coming from the
galaxy.
486
And only when you have a very good
understanding of your foregrounds, can you
487
go and can you look for fainter light that
is coming from earlier times.
488
Yeah, yeah, that makes sense.
489
Because also those waves are like so much
weaker that...
490
Also, I'm guessing you have to be a bit
more aware of what you're looking for,
491
because otherwise it's even harder.
492
And to understand, do we know if...
493
Just one black hole, for instance?
494
So for instance, the back hole at the
center of our galaxy, is it emitting also
495
gravitational waves, but since it's not
orbiting another one, at least that we
496
know of,
497
the gravitational waves are weaker so we
cannot see them?
498
Or do we know that, no, you have to have
the collision of two massive objects to
499
get those gravitational waves?
500
Yeah, so a single black hole won't do it
because anything that is perfect spherical
501
symmetry won't do it.
502
That has to do with the fact that these
gravitational waves are tensor modes,
503
right?
504
So they have two Lorentz indices and
something that's spherical symmetric.
505
is a scalar quantity.
506
So a single black hole won't do it.
507
So you need two, or you need a black hole
and another massive object, so you have a
508
black hole and a neutron star.
509
Okay.
510
Or anything else that breaks spherical
symmetry, right?
511
So kind of, I don't know, you dancing
around, right?
512
That will in principle generate
gravitational waves.
513
They're just very, very small.
514
Thank you.
515
I'm flattered.
516
Yeah, I see.
517
Okay.
518
Yeah, so it's very like, it's really the
density of the objects that count.
519
Yeah, again, you can imagine that.
520
A large concentration of mass and in some
asymmetric way.
521
So some sort of violent process, which is
condensing a lot of energy, a lot of mass.
522
Yeah.
523
But in some way that is moving in a bit of
a non-trivial way.
524
Yeah, that makes sense.
525
Even though I...
526
I like thinking about these things because
it's so hard to imagine.
527
Like the power of these collisions must be
just incredibly devastating.
528
I would love to see that in a way, but
that's so like, it's really impressive and
529
at the same time, really frightening.
530
Yeah.
531
So the, the gravitational waves that we
saw.
532
with LIGO, there we think it's something
like two black holes, roughly after the
533
mass, like roughly 10 solar masses each
colliding, a bit more.
534
And the energy that is just the energy
that is released into gravitational waves
535
corresponds roughly to the mass of our
sun.
536
So it's a huge amount of energy.
537
And now the gravitational waves that we
think we might have seen with these pulsar
538
timing arrays.
539
These are even more massive objects.
540
These are really the large black holes,
right, like the one in the center of a
541
galaxy that we think we see colliding.
542
So this is two far away galaxies, each
with their big, massive 10 to the 6 solar
543
mass black hole in the center.
544
And when they collide, that's the signal
that we expect.
545
So that's a massive event, right?
546
I mean, two galaxies colliding.
547
Yeah, you don't want to be close to
witness that.
548
Yeah, no, that's for sure.
549
These are absolutely fascinating topics
and I'm wondering what are the main
550
challenges in understanding these topics
right now and how do you folks as
551
researchers in this field...
552
address them.
553
That's, that's a broad question, right?
554
I mean, there's different levels of
challenges, right?
555
So when it comes down, for example, to
let's say something, something concrete,
556
like understanding these signals that we
think might be from gravitational waves,
557
then I mean, a lot of the problems boil
down to, you know, making sure this is a
558
signal and not a background or a noise
source.
559
So
560
That means, of course, building
experiments that are extremely precise
561
measurement devices.
562
It also means a lot of modeling of the
various components that go in, and kind of
563
both on from the theoretical side and also
from the experimental side.
564
And then when you get the data, again, to
cross-check, is this really the type of
565
signal that we have kind of...
566
Do we have a way, a robust way to
distinguish what we call a signal from
567
something that we call a background?
568
Take it into account that we might not
have thought of every possible background,
569
right?
570
So do we kind of really have a telltale
signal of what we think the signal would
571
look like, right?
572
And typically all these analysis are done
as blind analysis, right?
573
So you think about what signal you need to
see in order to be convinced that this is
574
what you're looking for before you open
the box and look at your data.
575
So that's one challenge.
576
more kind of on the data analysis or
experimental side.
577
The other challenge may be more on the
theory side.
578
So when you're kind of building models,
which extend to standard model of particle
579
physics, there's many, many options, and
you need some sort of guiding principle.
580
And I mean, if you're lucky, you have data
to guide you, you have some sort of
581
anomaly, something you feel like, okay,
here's the weak point, right?
582
Here's kind of where you need to poke,
where you need to extend.
583
Sometimes you have things like simplicity,
right?
584
Which you kind of hope is a good
principle, though, of course, you never
585
know that that's a good principle.
586
Yeah.
587
And recently, that's really been a bit of
a challenge, precisely because the
588
standout model works as well as it does.
589
There's no...
590
I mean, sure, we know we need to explain
dark matter, right?
591
But there's many, many possible options
how that dark matter could or could not
592
tie into the standard model.
593
And there's no very obvious way, like,
there's no obvious weak point at the
594
standard model.
595
It is not precise weak point.
596
I mean, there's a global weakness, things
that cannot explain, but it's kind of not
597
quite clear where exactly it needs to be
refined or extended.
598
And that I think for
599
In the past, it was more clear, or people
had pretty clear ideas, right?
600
And then there was pretty obvious things
that needed to be checked, right?
601
So we needed to find the Higgs particle,
right?
602
So the last missing particle of this then
our model.
603
And then we also thought, because the, I
mean, the Higgs particle has certain
604
properties, which kind of led us to
believe that we thought, okay, once we
605
find the Higgs particle, we should also be
finding other particles somehow related to
606
this particle that would naturally explain
certain open challenges.
607
But the fact that we haven't found them
and that we're just kind of testing with
608
higher and higher accuracy, and we're just
kind of getting the prediction of the
609
standard model or confirming the
prediction of the standard model without
610
finding any small deviations is making it
very hard to kind of decide a bit.
611
What's yeah, how, how should the extension
work?
612
Right?
613
And how should the extension like is, is
the extension in such a way that we can
614
actually test it with.
615
with the tools that we have, right?
616
Or do we need to think differently?
617
I mean, either different types of
experiments, but also maybe different
618
theoretical concepts, because so far, most
extensions of the standard model kind of
619
rely on the same theoretical framework
point of view theory.
620
And then they kind of within that
framework, you try different things.
621
But the fact that kind of we haven't had a
real breakthrough there.
622
maybe indicating, okay, whatever, you
know, it's just at higher energies, which
623
we can't reach, what may be indicating the
framework we're thinking in is maybe not
624
the best.
625
So yeah, there's many, many questions,
many levels of questions that can be
626
addressed.
627
Yeah, that's really interesting.
628
I'm curious, basically, what would you
like to be true?
629
something that at some point nature will
tell you, what would you like to see and
630
to observe and the kind of consequences it
would have on our understanding of how the
631
universe works?
632
Well, I would mainly like nature to
produce something that we can, like give
633
us something to work with.
634
I would like nature to be kind enough to
produce some sort of signal, be it in dark
635
matter, be it in gravitational waves, be
it at a collider.
636
that actually gives us something which is
accessible with the two worlds, the
637
experiments that we have at the moment.
638
Because it could simply be that all these
completions of the standard model live at
639
an extremely high energy scale, which is
simply inaccessible to any type of
640
collider we can build on Earth.
641
And that'll make it not impossible, but
very, very much harder to actually unravel
642
these questions.
643
Yeah, yeah, for sure.
644
And that, I mean, so that's one part of
the work you're doing.
645
I told that work around gravitational
waves, which are of course related to
646
gravity, in case people didn't understand.
647
Oh, and by the way, on the podcast, I had
another researcher called Laura Mansfield
648
and she's working on gravity waves.
649
which are not the same as gravitational
waves.
650
That's quite confusing, but yeah, that's
also actually very interesting field of
651
research, basically gravity waves and the
relationship with climate.
652
That's all here on Earth.
653
But that's also related to gravitational
waves in a way, in the sense that it's big
654
objects basically on Earth.
655
Like the Everest or the Mont Blanc or all
these big
656
massive mountains which actually distort a
bit the gravitational field around them
657
and that has impact on the climate.
658
How do you model that?
659
Basian modeling gets here because that's
really useful because you don't have a lot
660
of sample size.
661
I recommend listening to Episode 64.
662
I put that in the show notes.
663
Yeah, I was fascinated by the fact that
gravity, you can study it here on Earth,
664
but also it has incredible effects in the
universe and at masses that we cannot even
665
imagine, right, with the collisions of
black holes and collisions of neuron
666
stars, so that's really something I find
fascinating.
667
And actually, can you make the distinction
between a neuron star and a black hole
668
listeners and yeah, so that they
understand a bit the difference between
669
both.
670
Right.
671
So a neutron star is made of neutrons,
meaning kind of it's a very, very densely
672
packed environment of nuclear matter.
673
And a black hole is even more denser,
right?
674
So a black hole is really the densest
object that we can imagine.
675
where kind of matter has really any type
of matter has really just collapsed into
676
this object, and you don't care any much
anymore kind of what it was initially made
677
out of, right?
678
If we just has one property.
679
Of course, it can also spin, but
basically, it only has one property, which
680
has which is its mass, right?
681
And then it may also have spin if it's if
it's rotating.
682
But it doesn't it doesn't matter anymore
what it was made out of.
683
So one, one consequence of that is that if
you have two
684
neutron stars merging as they get very
close to each other, their gravitational
685
force will slightly distort them.
686
So they can be a little bit deformed
because despite that they are very, very
687
compact, and very dense, they can still be
kind of slightly deformed as they get very
688
close to each other, whereas two black
holes will really stay perfectly spherical
689
as they as they approach each other.
690
So you can tell the difference between the
two by looking at
691
details of the gravitational wave signal
as you approach this merger event.
692
Okay.
693
I didn't know that black hole stayed
spherical even as they approach each
694
other.
695
Is that because they are so dense that
they cannot be deformed?
696
Yeah, it's basically because they are so
dense.
697
And because they, I mean, in some sense,
despite that they are physical objects in
698
our universe, in some sense, they kind of
become a rather mathematical object.
699
Yeah, like a perfect sphere that you
cannot deform or do anything on.
700
It's really weird.
701
Yeah.
702
And it's crazy that we're actually seeing
them, right?
703
I mean, both in these gravitation wave
signals as also then with direct
704
observations with optical telescopes.
705
That's like this first picture of the
black hole in our galaxy and the
706
neighboring galaxy.
707
Yeah.
708
Yeah.
709
And so your work on gravity, I'm curious
to understand it because here, obviously
710
when we talk about gravity, gravity is so
weak that you have to have so massive
711
objects to really see its effects and also
it needs a lot of time.
712
So obviously here we're dealing with the
largest scales of the universe.
713
But you also work on particle physics, as
you were saying, and you work at CERN,
714
where particle physics is one of the
biggest fields.
715
So I'm curious, how does that study of
gravity intersect with the study of
716
particle physics, especially when we
consider the phenomena you work on, so
717
especially black holes and or the early
universe?
718
Right.
719
Well, I mean, anybody, you know, who's, I
don't know, fallen down the stairs, right,
720
will not say gravity is a weak force.
721
But indeed, right on Earth, right, when we
compare the force of gravity to the other
722
forces that we have, so the forces that
bind atoms together, things like that,
723
gravity is extremely weak.
724
So when we perform any particle physics
experiment on Earth, we just completely
725
neglect gravity, and we're not introducing
any error in our estimations.
726
Now, gravity can become important, as you
say, either if you have some very massive
727
objects like black holes, or if you have
very far distances, because here on Earth,
728
kind of, okay, we have so much matter
interacting so strongly that we don't care
729
about gravity.
730
But the universe as a whole is actually
pretty empty.
731
So in most of the universe, there's just
nothing.
732
What leading order, there's nothing.
733
And that means that on those scales,
because there's no matter which
734
has any interactions that are stronger on
those large scales, it's really gravity
735
that is describing the dynamics of the
universe.
736
And so if we want to understand both kind
of the dynamics of the universe today, but
737
also extrapolating back in past, if we
want to understand the evolution of the
738
universe, the birth of the universe, then
we need to understand gravity.
739
And one of the big puzzles, for example,
is
740
that at the moment observations tell us
that we are in a phase of the universe
741
where the universe is not only expanding,
but expanding in an accelerated way.
742
And that's pretty weird because normally
you think if you just have a bunch of
743
matter, right, a bunch of galaxies, you
think, well, they're going to have
744
gravitational interactions between each
other.
745
So even if you somehow gave them some
initial velocity, you would think, okay,
746
well, they're going to kind of slow down.
747
and eventually crunch back together again,
because on those large scales, it's only
748
gravity that is important.
749
So on those large scales, you think you
can you can either have things collapsing,
750
or you can have kind of things, at least
if they're expanding, they should be
751
slowing down.
752
What we observe is the opposite, right?
753
What we observe is really, things are
deferred, things are away from us, the
754
faster they are moving away.
755
So we're in a universe which is expanding
faster and faster.
756
And that is also gravity driving that.
757
It's just not the usual form of gravity
that we know on Earth, that gravity is
758
attractive.
759
But in some sense, you can call it a
repulsive force of gravity, or it's a part
760
of gravity that acts as a pressure that
drives the universe apart.
761
And that is what we call in dark energy.
762
So again, the term dark just implies we
don't really understand and we can't see
763
it.
764
And energy basically comes from
observations that it has this effect of
765
driving the energy of driving the universe
apart.
766
So it acts as a type of energy in the
expansion history of our universe and
767
concretely today.
768
But we don't really so we can model it,
but we can't we don't really fundamentally
769
understand what it is.
770
So understanding that and understanding
kind of.
771
how the universe evolved, not only today,
but in the past.
772
That then immediately ties back into
particle physics, because going back in
773
time in an expanding universe means you go
to a smaller universe where everything was
774
much more dense, much more hot.
775
You end up in this primordial soup of
particles.
776
So you're looking at particles at high
temperatures, particles when they're
777
really kind of not bound in atoms and
molecules, but when they exist really in
778
their fundamental
779
basically a lab to study particle physics.
780
So that's how the connection works between
these very large scales of the universe
781
and then the very smallest particles that
we study in that way.
782
I see.
783
Yeah, it's because then it's because
you're going back to the early universe
784
where basically the structure that we have
today of the universe didn't apply because
785
it didn't exist yet.
786
Correct.
787
Correct.
788
We go back to when everything was really
kind of just this hot primordial soup of
789
fundamental particles.
790
We tried to understand kind of how
different properties of the soup, meaning
791
different possible extensions of the
standard model, would kind of leave traces
792
in the evolution of the universe.
793
So would leave traces in kind of
astrophysical and cosmological
794
observations that we can make today.
795
I see.
796
And...
797
these days, what's a specific experiment
or project that you're involved in, in
798
this film, and what would be the main
question that this project is trying to
799
answer?
800
Right.
801
So a big, big project I'm involved in,
right?
802
So this is a, you know, many hundreds,
thousands of people working together is
803
the LISA project.
804
So that's a future space-based
gravitational wave observatory.
805
It's going to be an ESA mission.
806
The idea is to have three satellites
circling around the sun on an orbit
807
similar to the Earth.
808
So following Earth.
809
on an orbit around the sun.
810
The satellites will be two and a half
million kilometers apart.
811
They will exchange laser links.
812
So they will be shooting, there will be
lasers going between all combinations of
813
the satellites.
814
And using these lasers, the idea is to
measure very precisely distance between
815
these satellites as they orbit the sun.
816
And the idea is that if a gravitational
wave comes, since it's a
817
little ripple in space-time, it will
change very slightly the distance between
818
the satellites.
819
And so by kind of looking for this,
looking for these little variations in the
820
distance between the satellites, the goal
is to look for gravitational waves.
821
And being in space has the big advantage
that a lot of the noise that you have to
822
deal with on Earth is not there.
823
So the idea is that you can
824
much better sensitivities than you could
on Earth.
825
Yeah, that makes sense.
826
Also, although I'm guessing the sun can be
noisier at times.
827
Right, but it's all a question of
frequency, right?
828
So you need to kind of find a frequency
band which is clean.
829
But yeah, I mean, there's obviously huge
technological challenges in implementing a
830
mission like this and many things that can
go wrong.
831
This is why you need a lot of people with
a lot of different expertise coming
832
together and also a lot of money to build
an instrument like that.
833
Yeah.
834
I mean, just the engineering part of it is
you have to launch three satellites.
835
First, that's already hard.
836
And then you have to put them in orbit
around the sun and that they still can
837
communicate with each other.
838
It's just, and they are extremely far
apart from each other.
839
So just that part is...
840
absolutely incredible that we can do that.
841
Knock, knock, right?
842
I mean, we hope we can do it.
843
Yeah, I mean, that's just incredibly
fascinating.
844
And so what's the ETA on this mission?
845
When will the satellites go up
theoretically?
846
Right.
847
So the hope is to launch in the early
2030s, which seems a long way from now,
848
but it's really not.
849
Because, yeah, I mean, it takes a while to
build a satellite.
850
And also to develop all the kind of the
data analysis pipelines that you need.
851
Make sure you have all the sensors on
board that you might need to perform
852
whatever type of cross checks.
853
Yeah, make sure you didn't put anything on
board, which generates a bunch of noise.
854
Because once it's up there, it's up there,
right?
855
You can't.
856
Yeah.
857
Yeah, I mean, it's not in the orbit,
right?
858
Exactly.
859
You cannot find it, send anybody to repair
it, right?
860
So once it's up there, it's up there.
861
So you really have to think of every
possible complication beforehand.
862
Yeah, which is quite daunting.
863
I have to do that for my own statistical
model, you know, where I probe them and
864
I'm like, okay, where can the model fail?
865
What could be the potential issues?
866
It's already...
867
stressing me out, but then if you have to
do that for something you cannot go back
868
to, that's just incredibly daunting.
869
If you think a code release is stressful,
then imagine this.
870
Oh, yeah.
871
Oh my God.
872
But so fascinating.
873
Personally, what's your part in this
project, for instance, in the Lisa
874
project?
875
Right.
876
I'm in charge of coordinating research on
what we call
877
the stochastic backgrounds.
878
So the signals we've talked about so far,
and predicted the ones we see by LIGO, are
879
what we call transient signals, meaning
most of the time the detector actually
880
sees nothing, just noise.
881
And then from time to time, you have a
rather relatively strong signal.
882
You see it, then it's gone.
883
So if that's your data analysis challenge,
then you can calibrate your detector in
884
the signal-free moments.
885
You can learn all about your properties of
the noise and you can have a good noise
886
model.
887
And then when you get a signal, you can
kind of do a pretty good signal to noise
888
discrimination.
889
Now with Lisa, the situation is going to
be very different because we're going to
890
have, because it's such a sensitive
instrument, we're going to have lots and
891
lots of stuff going on all the time.
892
So we're basically not going to have
signal free time.
893
So we're kind of.
894
dealing with kind of measuring all these
different signals and the noise at the
895
same time.
896
And at the same time, the idea is that we
might have stochastic backgrounds.
897
So stochastic backgrounds could, they're
not transient signals, but there's kind of
898
more like a white noise, which is there at
all times.
899
They could be coming from unresolved
astrophysical sources, so unresolved black
900
or black or merges that are kind of out of
the range of our detector.
901
So we can't individually detect them, but
they just kind of contribute to some
902
confusion noise.
903
Or they could be these signals from the
very early universe, which is, of course,
904
the ones that I'm actually after.
905
But so you have to kind of dig them out
between all these loud transient signals,
906
between these possible astrophysical noise
like signals, which look very, very
907
similar to the kind of cosmological noise
like signal that you will be looking for.
908
And of course, the words are very, very
similar to instrument noise that you might
909
have mismodeled or misunderstood.
910
So.
911
And what I'm working on is okay, a on on,
okay, understanding the possible models
912
for these for these different components,
in particular for the cosmological
913
sources, but also trying to understand how
could we if we you know, actually get some
914
actual data, how can we actually
disentangle all of these components?
915
And how can we really kind of make the
most of the of the mission, extract as
916
much information as possible?
917
which with all these kind of overlapping
signals and challenges.
918
Yeah, yeah.
919
And I'm guessing that having to do that,
not in a few months is something you
920
appreciate.
921
Yes.
922
Yes, yes, yes.
923
Yeah, so there's many challenges out
there.
924
Obviously, many people working on it.
925
And I mean, luckily, as you say, luckily,
we don't have to solve this in a couple of
926
months, right?
927
Because we're basically also counting on
things like computing power, and so on,
928
increasing new methods becoming available.
929
But, but yeah, so it's, but still, I mean,
the development has to happen now.
930
Because if we kind of figure, okay, we
need a certain type of
931
sensor or some certain type of output data
that would help us to discriminate these
932
different signals.
933
We can't come along with that when the
mission is already built or even worse,
934
already launched.
935
So you can't wait till you see the data to
decide how you're going to do the
936
analysis.
937
You at least have to have a very good idea
of how you're going to do the analysis
938
before you see the data.
939
And then maybe you can refine once you see
the data.
940
Yeah, definitely.
941
Actually, this kind of work that you do in
theoretical physics or that kind of
942
project you just described, it really
involves the development of models, of
943
hypotheses, and I'm curious if you have
some favorite hypotheses or models or the
944
most intriguing theoretical ideas.
945
that you've encountered in your field and
that you'd like to see tested.
946
And if we could actually test them right
now with our current technology.
947
Good question.
948
I must say, I don't have a particularly
favorite model.
949
I don't feel, I don't know, protective
ownership of any particular idea.
950
I'm more the type of person who I start
working on something because I find it
951
interesting.
952
And then once I've understood it to a
certain degree, I move on to the next
953
topic.
954
But I think there are a couple of kind of
big overarching...
955
questions, right?
956
So kind of, yeah, understanding, getting
some experimental input on what on what
957
dark matter is, would really help a lot on
the on the theory development side.
958
As I mentioned, when we also have issues
understanding the Higgs particle,
959
understanding in particular mass of the
Higgs particle, which is potentially
960
indicating there's something we don't
understand properly about quantum field
961
theory about
962
that I find is incredibly exciting,
because it would really mean kind of,
963
okay, not an add on, you know, not a small
extension of our existing model, but
964
really, completely revolution and how we
think about things.
965
Yeah, of course, it also makes it much
more difficult, right?
966
Because you don't even have the framework.
967
Maybe we don't even have the mathematical
framework to think about this.
968
It's a huge step to take.
969
So I would, I mean, that's what would be a
big step, right?
970
So I'm not sure if and how that's going to
happen.
971
If it's even necessary, right?
972
Maybe the current framework is totally
fine, but that would definitely be a
973
development that on just on the pure
theory side, that would be very exciting
974
to see happening.
975
Yeah.
976
Yeah, for sure.
977
Definitely.
978
I kind of, I'm also really curious about
that.
979
Actually, is there one big question that
you would like to see answered before you
980
die?
981
Your one big question that you'd really
like the answer to.
982
I think I really would like to know the
answer to Dark Matter.
983
Just because that-
984
It's well, there's this we have many, we
have many very reasonable models, which
985
can be tested and which are being tested.
986
So we could still be unlucky and nature
could choose not one of these nice and
987
reasonable models, right, but something
completely different.
988
But that that's a field where there are
some very good suggestions and they can be
989
tested.
990
Now, unfortunately, there was one
excellent suggestion, right, which was
991
supersymmetry and the dark matter particle
that comes with supersymmetry would have
992
solved, was mathematically beautiful,
would have solved a ton of questions, was
993
in many ways the perfect theory, right?
994
Unfortunately, we didn't find it.
995
So it could still be out there, but kind
of not as a solution to all of the
996
problems that we hoped it would solve.
997
Because if that were the case, we should
already have seen it.
998
Yeah, so something kind of being the ideal
theory from our point of view, doesn't
999
mean nature actually cares, right?
Speaker:
Yeah, for sure.
Speaker:
And does it that way.
Speaker:
But yeah, so Dark Matter, I think it
really has the potential that we could
Speaker:
actually find it.
Speaker:
And if we find it, that could really be a
starting point of a whole new exploration
Speaker:
of questions.
Speaker:
Yeah, definitely.
Speaker:
And that's interesting that you mentioned
dark matter too, because Kevin Clive, I
Speaker:
asked him the same question and he
answered dark matter too.
Speaker:
So that's interesting to see that it's
really something that's picking up in the
Speaker:
physics space these days where it seems
like we're less, let's say we're more
Speaker:
hopeful that we can actually start making
sense of it and probing
Speaker:
the universe in a way that will give us
some answers, at least to this mystery.
Speaker:
Whereas dark energy, from what I
understand, we understand way less about
Speaker:
dark energy than we understand about dark
matter for now, right?
Speaker:
Yeah.
Speaker:
That's correct.
Speaker:
And also there we have much less, I mean,
we see what it does on large scales,
Speaker:
right?
Speaker:
But we have also much less of an idea how
to make progress.
Speaker:
Both on the theory side, there's kind of
not these kind of clear cut models that
Speaker:
kind of say, okay, here's a good theory of
why it is how it is, and here's how you go
Speaker:
test it, right?
Speaker:
For Dark Energy, we have neither.
Speaker:
Neither a clear cut theory that kind of
says, okay, here's a good explanation, nor
Speaker:
any way of probing them really.
Speaker:
So it's a much, it's much more in the
blur.
Speaker:
Yeah.
Speaker:
So hopefully.
Speaker:
In 10 days, you'll come back to the show
and we'll talk about Dark Energy and the
Speaker:
latest progresses.
Speaker:
Valerie, I think I have so many more
questions, but you've been already very
Speaker:
generous with your time.
Speaker:
Before closing up, is there any topic I
didn't ask you about and that you'd like
Speaker:
to mention?
Speaker:
I think we covered a lot, but nothing
particular comes to my mind.
Speaker:
Okay.
Speaker:
Well, then I think we can call it a show,
but as usual, before I think you go, I'm
Speaker:
going to ask you the last two questions I
ask every guest at the end of the show.
Speaker:
First one, if you had unlimited time and
resources, which problem would you try to
Speaker:
solve?
Speaker:
Yeah, that's as I said, that's actually a
really tricky question because we are in
Speaker:
this in this situation that I find it very
hard to pinpoint.
Speaker:
where is the weak point of the standard
model?
Speaker:
Where should we poke it?
Speaker:
Right?
Speaker:
So from the pure theory side, without any
experimental input, I feel like if I had
Speaker:
unlimited time and resources, I wouldn't
engage on a single project right now.
Speaker:
But I would basically just try and, you
know, gather as broad as possible
Speaker:
understanding of
Speaker:
as many concepts as possible and hope that
we will eventually get some sort of data,
Speaker:
which points us in the direction we need
to explore.
Speaker:
I don't at the moment really have a clear
cut avenue where I say this is where I
Speaker:
would put all my money.
Speaker:
Yeah.
Speaker:
So wise answer where you don't put your
eggs in the same basket.
Speaker:
And second question, if you could have
dinner.
Speaker:
with any great scientific mind, dead,
alive or fictional, who would it be?
Speaker:
Yeah, I think, well, we'd go for somebody
dead, right?
Speaker:
Just because that's a chance you don't get
on a regular conference dinner.
Speaker:
So I'd be really curious to talk with some
of the people involved in the discovery of
Speaker:
quantum mechanics.
Speaker:
So say Heisenberg or somebody like that.
Speaker:
Because I feel like they were kind of...
Speaker:
at the core of the field, when the field
was also in a situation where it was kind
Speaker:
of not so clear cut, at that time, not
even clear cut that it was a need to kind
Speaker:
of extend the current understanding
because classical physics was well
Speaker:
understood, right?
Speaker:
And nearly all phenomena were very well
understood.
Speaker:
And people were thinking, okay, you know,
physics, it's done, you know, we
Speaker:
understand nature.
Speaker:
And it was just kind of very small.
Speaker:
tweaks here and there, right, that kind of
were a bit confusing.
Speaker:
So one could have easily believed
everything is done and understood, go
Speaker:
study something else.
Speaker:
But they kind of opened the door to the
world of quantum physics.
Speaker:
And with that then came quantum field
theory, with that came kind of elementary
Speaker:
particle physics, with that came kind of
all the questions that we have today.
Speaker:
So actually, from today's point of view,
Speaker:
we would say, well, they understood very
little, right?
Speaker:
It was a whole bunch of new physics that
was kind of not known to them, but they
Speaker:
didn't even know that it was not known to
them, because there was kind of no glaring
Speaker:
open question.
Speaker:
So I'd really be curious to know how they
perceived that situation and how they got
Speaker:
to the point of opening the door to the
quantum world and taking up that
Speaker:
challenge.
Speaker:
Yeah, yeah, yeah.
Speaker:
Yeah, definitely sounds like a very fine
dinner.
Speaker:
Please invite me.
Speaker:
So, well, awesome.
Speaker:
Thanks a lot, Varyry.
Speaker:
That was absolutely fascinating.
Speaker:
We didn't talk a lot about stats, but I
love doing these episodes from time to
Speaker:
time, you know, where we de-zoom a bit
from stats and just talk about fascinating
Speaker:
science in general.
Speaker:
I think it's very interesting and also
quite important to put more rigorous
Speaker:
pedagogical scientific content out there
in the world.
Speaker:
We've seen that in the recent years.
Speaker:
So thanks a lot for doing this for us,
Valérie.
Speaker:
I will put a link to your website in the
show notes for those who want to dig
Speaker:
deeper.
Speaker:
Also feel free to add any link to cool
papers or experiments or videos that you
Speaker:
think listeners will appreciate.
Speaker:
And thank you again, Valérie, for taking
the time and being on this show.
Speaker:
Thank you.
Speaker:
And rest assured that stats is still at
the basis of all this, despite that we
Speaker:
took a more high-level approach in this
discussion.
Speaker:
Yeah, for sure.
Speaker:
Well, thanks a lot, Valerie, and see you
soon on the show.