(upbeat music) (audience applauding) - Well, thank you
everybody for being here. When it became clear to me
that I'd be talking on Friday evening at pop time while
the tubes on strike, I thought I'd be standing here alone. So I guess this is the
most dedicated audience I'll ever get. Existential physics, yes. I gave a talk about this
about two months ago at a literature festival and
they didn't like the title. So when I showed up and
I looked at the program, I found that I'd be talking
about the meaning of life. And I'm afraid it will not be, it will not get quite
as existential as that. But I thought I'd start with explaining what I'm even talking about. What is existential physics? What I mean by this is
those aspects of physics that concern human existence. For example, the nature of time. What changes the
beginning of the universe? Where do we come from? The structure of matter. What are we made of? Constraints, limits, what can
we do and what can we know? Now, people who have known me
for some while would find this quite a change of direction. I'm more known for talking
about what we can't do. So if there are some headlines
in the popular science news that proclaim that we can travel faster than the speed of light, or we can send information
faster than the speed of light with the quantum internet
that is soon to be coming, or that we can create negative mass or make contact with parallel universes, then I'm the one who has to say, "No, you can't do this. No, they didn't do it. No, they haven't done it." And I do think that this is kind of important debunking headlines, but it's also in the course of time, it's become a little bit depressing. And I found that it portrays
a very one-sided picture of physics and also of me. So I wasn't quite happy with it. And I thought there's
more to physics than that. Physics also tells us what is
possible and it opens our mind to new possibilities. And maybe that's a little bit surprising. It's not quite how we think of physics, that it tells us something
about quite spiritual ideas, something about our own existence. But if one thinks about
it a little bit more, I think maybe it's quite natural. So I've tried to draw on
here science, philosophy, and religion with some fuzzy boundaries to make clear we are not really sure exactly where they end
and where they begin. And the foundations of physics are kind of slightly overlapping with
philosophy and religion and the scientists who work on it are not always quite clear
which site they are actually on. And I think what I mean
with this will become clear in the duration of this talk. Okay, before I say anything else, I have to say that everything
I'm going to say today is just for all we currently know. So when I was writing my book, I realized that I was
constantly using this phrase, "For all we currently know" this and this for we
currently know it's so and so. And then in the end, I just
put it in the preface and said, "Everything I'm going to say
should come with the phrase, 'For all we currently know ahead'." And the same is true for this talk. So I want to start with the question, does the past still exist? And this is a question which
has been brought to our attention basically by * relativity. And there's a lot to say about relativity, but I'll try to make it
fit into a one hour talk. There are three important
ingredients that we need to know. One is that the speed of light is finite. It's very large, 300,000
kilometers per hour, but it is finite. It's the same for all observers. So it doesn't matter if
you're running which direction you're running, the speed of light is always the same and nothing goes faster than light. And to be precise, the last two are only two for the speed of light in vacuum. But I'm a theoretical physicist. So we always do our thought
experiments in vacuum. Now this sounds kind of innocent at first, but if you think about it a little more, it has a perplexing consequence. If I ask you very simple
question, am I here now? Then the answer is, well, you can't tell because
by the time you see me, I'm already moved on to the future. So you always see me like I
was a little bit in the past. Now of course this is a
ridiculously tiny amount of time. You could go and measure the
distance and calculate how long it took for the light to
travel from me to you, and it would be a fraction of
an nanosecond or something. So kind of not exactly
what we would notice. But in principle that's true. And as I said, the speed of light is a maximum speed. So it's true for all possible
information that you can receive everything you see,
everything you perceive, you perceive it as it was
a little bit in the past. Now you could say, well, but I do know what the speed of light is, so I can just calculate how
long did it take for the light to get from me to you? And then I could say, well, when you actually said the word so and so, I was just scratching my
head or something like this. So you could try to say, well, I can figure out which two
moments belong together. So you could try to
reconstruct a notion of now, but it turns out that this
is not all that simple due to relativity. Now maybe the normal
person's reaction would be, oh my God, physicists. But as I say, I think just because you're
here on a Friday evening listening to a public lecture
and existential physics, I guess you're not quite the
average person on the street. So I'll try to explain this
in a little more data why relativity is weird and why
it makes it so difficult to define a notion of now. So suppose you're standing
on a hill or something and you're looking at
a train that's going by from the left side to the right side and your friend is in the train standing exactly in the middle. And if the train hits
a particular position where the red arrows are, there'll be light flashes
triggered in the train. So they are the light flashes. And the question is, do you
see them at the same time? Now keep in mind that she's directly in the middle of the train. Those two light flashes are
exactly at the same distance from her and they're also at the same distance from you. the speed of light is always the same. So if you want to figure
out what will you see where you can just forget about the train doesn't really matter and
the light arrives at you and your conclusion is, well, they must have been emitted simultaneously if they arrive at me at the same time, because I know they have exactly
the same distance so far, so obvious. But now what does your friend
see when she's on the train? Well, so again, the light flashes, but now the train moves
on and she moves towards, one of the light beams that's
submitted from this flash and away from the other one. So it seems to you that
clearly she sees one of those earlier than the other one
and she would say, well, they're not simultaneous. So two events that happen
at the same time for you do not happen at the same time for her. And it might seem like this is just a quirk of your perception that comes from this weird
arrangement or something. But it turns out in relativity, in Einstein's theory of special relativity and also in his theory
of general relativity, that's the general feature. It's just impossible to
construct a notion of now that does not depend on the observer. This notion of "Now elsewhere" always depends on where
you are and how you travel. So it's kind of a very
personal thing actually. And it has the consequence
that your past maybe somebody else's present or the other way around. You're present may be
somebody else's future. And the only logical conclusion
that you can draw from this is that either nothing exists now. So this is one conclusion
that you can arrive at. You can just deny that you
can say anything about what exists at this moment elsewhere, or all moments exist the same way. And well, I don't know about you, but I'm quite used to talking
about things that happen elsewhere now. So I think that's just a natural
sense in which we use the word now and then we arrive
at the conclusion that really all moments exist in the same way it's called the block universe. It's a consequence of Einstein's theories and it clashes with our
intuitive perception of time. We perceive one moment as now and we think it's a special moment, but according to Einstein's theories, all moments are equally
special in that regard. So the block universe, it
kind of just sits there. There's no particular
moment singled out in it, which corresponds to this
moment of now that we perceive that comes from our particular position in that block universe. In the block universe, different time don't seize
existing if you're not there. The same way that different
places don't cease to exist if you're not there. Now I asked, does the past still exist? According to this, the answer is yes, the past exists the same
way as the present does. Why did I not ask about the future? Well, it's because quantum mechanics makes the story a little
bit more complicated and I'll say a little bit
more about quantum mechanics in a moment, but yeah, so does the past that exist
for we currently know, the answer is yes. And I know a lot of people
find this surprising, but it's actually quite
uncontroversial in physics. It's one of those things
that we learn as students in the second year or something and the first time we hear about it, well, like this can't possibly be true, but the mathematics is
not all that complicated and this has been thought
through many times. And so yeah, for we currently
know it's actually correct. So there's another way
that we can look at this from a slightly different perspective that I want to talk about now. Can information be destroyed? So before I go on, I have to say that the way
that we talk about information in the foundations of physics, at least in the areas that I work in it doesn't mean a terrible lot, it just mean it's all the
details that you need that you need to specify a system at
one particular moment in time. We also call this an initial
condition in a classical system that you are used off,
like for Newton's laws, throwing a stone or shooting an arrow, that kind of stuff. It would be the position
and the initial velocity. That would be the entire
information about the system. In more complicated systems, it's more complicated information, there are more numbers, but basically that's what it is. In other areas of physics, information means more than that, but this is the way
that I'll use it today. So all fundamental laws we know in the foundations of physics
work in a particular way. They work by using differential equations. And it sounds a little bit complicated, but really the only thing that
it means is that we specify all this information about
the state of a system at one particular time and then
we use this equation to calculate what happens later. Or we could also calculate
what happened earlier. Indeed, this equation,
which we call an evolution, not just connects two different times and it's a one-on-one map. So if I give you the information, the entire information of
a system at any one time, you can calculate what
happens at any other time, both forward and backward in time. In principle, this time
evolution is reversible. You can do it forward
and backwards in time, which means that this
information is just reconfigured, it's never destroyed. So it doesn't really seem
to match with our experience again, because it's certainly the case that the information can
get so badly scrambled that we can't use it for anything. Because, so for example, if you take a book and you burn the book, so in principle for for all we know about the fundamental loss of nature, the information about the
book cannot be destroyed. It's still there, it's there in the ashes and in the smoke and in the tiny correlations between them and they spread out through the room. There of course means that for
us it's completely useless, this information, but
according to our equations, it's still there. Okay, so this is all
fundamental loss we know. Except there are two issues. One is the measurement
in quantum mechanics and then there's black hole evaporation and I'll talk about those
in a little bit more detail. So in quantum mechanics we
also have this fundamental law, which is a one-on-one map from
one state to another state, and that's called the * equation. The * equation tells us how
the wave function changes and the wave function
is the thing that we use in quantum mechanics
to describe everything. Quite literally there's a
wave function for anything, could be an individual
particle like an electron, or it could be a molecule
or it could be a cat. So that their wave
functions for everything. The wave function is just
the device to calculate probabilities. So that's the peculiar thing
about quantum mechanics is that we can't actually directly observe the wave function. We can only observe the probabilities of getting a particular outcome. And I've tried to illustrate
one of the consequences with this little figure. So the wave function could tell
you that you have a particle which has a 60% probability
being in one place and the 40% probability
of being in another place, but now when you measure the
particle you know where it is. So you have to update the wave function for being 100% wherever
you have measured it and zero in all the other places. Now the issue with this is
that there could have been many different wave
functions that could give you the same result. It could have been this
particular wave function with 60 here and 40 there, and then it would've been
a fairly likely outcome to measure it on on the left peak, or it could have been
the other way around. And you were just particularly
lucky to see the particle in a place where it was unlikely to be. But still you saw it there. And what this means is that this, sorry process is not reversible. If you know what the outcome
of the measurement is, you cannot find out what
the initial state was. You don't know what the wave function was. So measurements in quantum mechanics, the way that we use them at the moment just in the mathematics,
are not reversible. So they break this idea
that information survives, but do they really describe what happens? So that's a big open question. It's called the measurement
problem in quantum mechanics. A lot of people, including me, don't actually think that
the measurement update is fundamentally the correct process. It might only be an approximation
to a yet to be found better underlying theory in particular because it brings up some
inconvenient questions like who measures the universe? If you want to make a theory
for the entire universe, you write down the wave
function for the whole universe. Well, who measures this? It doesn't really make any sense. So the way that we are
using the theory right now, it seems to be missing something. So what's with black holes? Well at first sight, it seems if you have a black hole and you throw something in
and there could be a book or something else, then the information just
gets lost behind the horizon. And you could say, well, okay, so, but it's just sitting
there behind the horizon. Just because I can't
retrieve it doesn't mean it's actually been destroyed. It might still be there for all we know. And that was the situation
before Stephen Hawking. And then Stephen Hawking
came and said, well, but actually the black holes
don't continue to sit there. Instead they evaporate,
they emit quantum radiation. And the issue with this radiation is that it's basically random. It doesn't contain any information other than the mass of the black hole and the electric charge
and the angular momentum. So the radiation does contain three bits, if you want to put it this way, but that's not very much in particular, not an entire book. So to give you a sketch of this problem, suppose you have some initial black hole you throw a book in, or Turkey, or apples, or whatever have you, and you create a slightly
bigger black hole in all of those cases, we assume it has the same mass. Then the thing evaporates and you are left with this random radiation. And again, you have the same problem as with the measurement process. If the only thing you have
is this random radiation, then you can tell well what
the mass of the black hole was, but you have lost all
the information about what was inside the book
or the name of the Turkey or what have you. So black hole evaporation
again seems fundamentally irreversible as opposed to
things that are apparently irreversible to us like burning a book. So at least in our mathematics
black hole evaporation seems to work entirely differently. And this is what gives rise to the black hole information loss paradox, which you've probably heard about. Black hole evaporation is inconsistent with quantum mechanics
because quantum mechanics before you're making a
measurement is time reversible, but a black hole even
without making a measurement, breaks this time reversibility. So it just mathematically
it doesn't fit together. It's an actual
inconsistency in the theory. Most physicists believe
that something is missing in Hawking's calculation
and that the process is actually reversible. That is quite plausible
because we don't have a theory to describe the quantum behavior
of space and time itself. So that's called a theory
of quantum gravity. Since we don't have this theory, it's not included in the calculation. So quite possibly that's it. The problem is the Astra
physical black holes that we have experimental evidence for that we see out there in the cosmos, they have an extremely low
temperature of this radiation. It takes hundreds of billions of years for them to evaporate. Actually at the moment they
wouldn't evaporate at all because even the cosmic
microwave background is hotter than the temperature
of those black holes. So it takes a really, really long time for black hole to evaporate. And so we can't experimentally test what's actually going on. So really we don't know. So what's the conclusion
about the question? Can information get destroyed? Depends on what you believe
happens in a measurement and black hole evaporation. I think the answer is no, but I don't want to talk too
much about my own opinion. If you want to know, you can ask me later. So since we were already
talking about astral physical things let's talk about
the entire universe. How did that begin? So that's a question which
sits very much on this overlap between science and
religion and philosophy. How did the universe begin? Wasn't especially made for us? Does does it need a creator? Others questions that to which we can have find the answer and so on. And the foundations of physics
side in in this entire mess, so to speak. So how does modern cosmology work? Yeah, that's Einstein again. Modern cosmology is based
on Einstein's theory of general relativity, which says that gravity
is really an effect of the curvature of space time. And this theory tells us
that the universe expands because there's matter in it. The rate of the expansion is determined by the amount of matter
and energy in the universe. So it's a little bit
different depending on if there's more radiation or more matter if you have dark energy and so on. And from measuring the rate of expansion, we can figure out roughly speaking, to make a long story short
what's in the universe and this theory or this
particular model for cosmology, which is called sometimes
called the concordance model or sometimes called lambda CDM, some people call it the
standard model of cosmology. It's made a lot of correct predictions. It makes predictions for
the formation of structures like how quickly the structures form and how they distributed predicted the cosmic microwave background
and also the properties, the abundance of light atoms, redshift of this galaxies and so on. So it's a good theory, let me put it this way, but it has a peculiar property, which is if we take those equations and we extrapolate them back in time, then at some point the energy
density in the universe becomes infinitely large, which doesn't really make a lot of sense. It just creates a singularity. It's not just the energy density of metal that becomes infinitely large. Also the curvature of space
itself becomes infinitely large. And what does that mean? It doesn't really seem
like something that could possibly be physically real indeed, Pretty much no physicists I know thinks that this is
actually what happened. More likely it just indicates
that the equations break down. So now what? Well, one of the reasons those equations probably break down is what
I already said earlier. We don't have a theory
for the quantum properties of space and time, which should become important somewhere when the energy density gets very large. So basically the answer is we don't know. But as you probably know, physicists have put forward
a lot of different theories. So for how the universe begins. So how did this come about? Well, remember how natural laws work. We just talked about
this some minutes ago. If you have a final state
and an evolution law, you can roll this back in
time to an initial state. And now if you take this initial state and you roll it forward
with the same evolution law, you'll get the correct final state that agrees with your observations. And you can always do this
if you have an evolutionary, you can always create an initial state. So at first sight it seems
a little bit perplexing. How can we ever figure out
what's the right evolution law if we can just form
together an initial state that'll work together with it
and give us what we observe. Now if we do this through
our everyday life, shooting your arrow or throwing a stone, then you can test these
situations by choosing a different initial state. You could shoot your arrow
in a different direction from a different position, or you could take a movie and look at where it is at any moment of time and extract the evolutional from this. But we can't do this
for the entire universe. There's only one initial
state and we can't take a movie of 13 billion years. So that doesn't work. So how do you ever know
what's the right law for the universe? Well the way that we do this in cosmology is that we take the law, which is the simplest, and that's the concordance
model that I just talked about. But if you are willing to leave aside this requirement of simplicity, you can change the
evolution law back in time. And this gives rise to all
kinds of different stories for the beginning of the universe. And those are the stories that
you've probably heard about. So since we don't have
evidence for for what happened at those high energies
in the early universe, it's possible to change the equations. Usually the way that this works is that you choose an equation
which looks very similar to the one that we have in Einstein theory up to some time very early in the universe where safely no one has any good data. And then before this you
can change the equation whatever way you like basically. And this gives rise to all
kinds of different explanations. Instead of a big bang, you could have a big bounce. So this happens if you
have an earlier phase of the universe which contracts and then it doesn't run
into your singularity, but it reaches a smallest size and then it starts to expand again. This is called a bounce. Those bounces could repeat, in which case you get a cyclic universe. You could start with a face
that is neither space nor time. This is called a no boundary proposal and was proposed by Hartle and Hawking. You could start from a black
hole and there could be a five dimensional black hole. It could be a gas of
strings or it could... Actually, I have those mixed up. Okay, yeah, sorry, I've confused myself
over what I wrote there. It could be something that
has neither space nor time, like a network of sort. This is something which
people have also proposed. So you just have a network of points and our notion of space, which emerges at a later time, comes about if the network shares a lot of connections. So it resembles kind of a
smooth letters basically. So what's the problem with all the those? Well, a good scientific
explanation must be simpler than the observation
it's trying to explain. And it should be as simple as possible. Unnecessary assumptions are not allowed. And this is the problem
with all those stories about the early universe. They make a simple story more complicated. So the simple story that we have is the standard model of cosmology, which if we roll it back in
time gives us the big bang. We think that this is probably wrong. So we don't know how the universe began and this is for what science is concerned is really the only thing
we can reliably say. So what's with those other theories for the beginning of the universe? Well, they're mostly not wrong, but we can't tell that
they're right either. So we just can't apply
the scientific method to pick any one of them. They're all fit to our
observations at least so far. So the way that I like to think about them is that they're basically
modern creation myths written in the language of mathematics. And you can believe
whichever one you like. My friend and colleague Tim Palmer has called those "Ascientific", and I think it's a good term. It's not that they are
somehow unscientific that it'd be going too far, but science doesn't say anything about whether they are right or wrong. So did the universe begin? We don't know and we may never know. Okay, speaking about universes, let's talk about some more
universes in particular. I want to talk about the multiverse and the question whether
copies of us exist. You've probably heard of the multiverses. So it's this idea that our
universe isn't the only one, but there are many, many
other universes out there, possibly infinitely many of them and the multiple multiverses so to speak. Brian Green has written a book in which he lists nine of them. I don't want to go through all of them, but I want to briefly remind you of the most widely
known ones, so to speak. One is eternal inflation, which has it that our universe
was created from a quantum fluctuation of some kind of field. This field is called the "Inflaton field". It doesn't really matter
if you don't exactly know how this works. The relevant point is just
that there isn't only one of those quantum fluctuations, but there are many of
those quantum fluctuations and they continue to
have more all the time. So there isn't just one
universe that's created from this inflaton field. There are actually infinitely many, so there're infinitely many big bangs each give rise to their own universe and they're more of them as we speak. Possibly the contents of
nature in those other universes are not exactly the same as
they are in our universe. So they could be very different. Some of them might be hospitable to life, others might not be hospitable to life. What's the problem with this? Well, the issue is that those
other universes are entirely disconnected from us. There are no observations that we can make that could refuge or
confirm that they exist. And it's not just that we can't see them like we can't look at them or it's something specific about light. There's no observation that we can make that could tell us whether
they actually exist. There are other versions of
the multiverse for example, if our solar system and our planet and us, We grew out of such a quantum
fluctuation in the early universe and then in
this meta distribution there were smaller fluctuations
that gave rise to planets, galaxies, and so on and so forth. If this happens infinitely many times, then our planet and everyone
and everything on it should repeat with small variations. So there are copies of
us somewhere out there. Again, the issue is that we
cannot possibly measure those. So they're out of call in contact with us. We cannot figure out
whether they actually exist. There's no observation
that can refute or confirm that they are actually out there. And to name one third
example of the multiverse, it's the many words of
deportation of quantum mechanics. So as I said earlier, the way that we typically
think about a measurement in quantum mechanics is that the moment you observe something, you update the wave function. It's also sometimes called
the reduction of the wave function or the collapse
of the wave function. So it's all the same thing. Strictly speaking, this is only one particular
interpretation of quantum mechanics and the many
words interpretation is a different interpretation. It has it that when
you make a measurement, it's not that the wave function collapses, but each possible outcome
happens in its own universe. So if you have a particle
that has 50% chance of going to the left side of the screen, 50% chance of going on to
the right side of the screen, then you're making two universes, one in which the particle
went to the right side of the screen and one in which it went to the left side of the screen. The issue is just that we
don't see both universes, we only see one of them. So for us it looks exactly the same as if the way function collapses. So there's no observation
that can refute to confirm that those copies in the
multiverse actually exist. So why do physicists believe that those other universes exist? I've thought about this for way too long. I've thought about it for
so long that I've wrote and entire book about it. I think the issue is that
they've become "Lost in Math". Just because there's math
first doesn't mean it's real. So this is what's going on
with all those multiverses. They have a particular theory and some of what the mathematics
in this theory describes, agrees reasonably well
with what we observe. And then they conclude that everything that's in the mathematics
also has to be real. And I think that's a
pretty big leap of faith. It's definitely something that
doesn't automatically come out of science. You can assume that it's real. You can do this if you want to, but that would be an
unnecessary hypothesis. The same as the case by the way, if you assume that those
other universes are not real, that's also an unnecessary hypothesis. Doesn't help us to describe
any kind of observation. So science can't tell you
that those copies are real, those are other universes
with the copies of you. But it also can't tell
you that they're not real. So do copies of us exist? Well, you can believe it if you want to. Nothing speaks against it, but nothing speaks for it either. Okay, so this all sounds a little bit, oh, you can make up your
mind one way or the other. So I want to finish with one example where we can actually answer a question, which is whether particles can think. And just to be clear, by particles I mean fundamental
and elementary particles. Think of an electron for example. So why would you think
that particles can think, well this idea has become kind of popular in an admittedly small
group of philosophers, but they're very vocal, it's called panpsychism. And it's the idea that everything
is a little bit conscious because it contains proto consciousness. So it's not just human beings or maybe, some particularly smart animal that you might think are conscious, but literally everything,
glass, carrots, whatever. But in most cases you
don't really notice it. So the idea is that this
explains how consciousness comes about because if you combine
things with this proto consciousness to something
that's large enough, then at some point it
can become conscious. Now if this proto consciousness isn't a physically real thing, then this is just a
weird version of dualism where you have the physical world and then you have kind of a mental world that is completely disconnected
from the physical world. And again, that's something
which you can believe in if you want to. There's nothing wrong with it exactly, because it doesn't connect
to any observation. So this would be an ascientific idea, but if the consciousness
stuff is physically real, and this is what most of the
panpsychism actually argue, then it it better agree with physics. So let's look at what physics says. This is the standard
model of particle physics. Those are all the fundamental
particles that we know at the moment. You not have to count them. I can just tell you that 25 of them, and we have tested this
model forwards and backwards. Actually the greatest problem, so to speak of particle
physicists at the moment is that it works too well. They would rather see it fail, but it's hold up extremely well. So what do we learn from
particle physicists? Well all those elementary
particles in the standard model are defined by their quantum numbers. And what's the quantum number? Well, quantum number things
like the electric charge, that's one that you're all used to. There's also something called a spin that's like a more complicated version of an angular momentum. And they're more complicated things like the weak hyper
charge stuff like this. And they're all just literally
numbers like one half, two over three, stuff like this. And those numbers completely
specify the properties of the particles. Now why is this relevant? Well it's because if
we're trying to calculate what the outcome is of
a particle collision, like we do for example, at the Large Hadron collider, of which you see an example
in this wonderful figure. So what you are looking into the beam axis so that the protons coming head on and then they collide and
produce a large number of new particles which
end up in the detector. And then you have to reconstruct
what actually happened in the reaction. And it has to agree with your theory and it agrees pretty well
with the standard model of particle physics. Now the thing is, if elementary particles had
any other degrees of freedom, any other numbers that
you could attach to them, then those that are in
the standard models, then the outcome of
those scattering events would be different. And the reason for this loosely speaking, is that the standard model
is a quantum field theory. So it's a type of quantum theory, basically a complicated
type of quantum mechanics. And in a quantum theory everything that can happen will happen. So if you give those particles
more internal states, then you will produce them and
that changes the probability that you will produce them. So it just doesn't agree with observation. So what we conclude from
this is that this proto consciousness can only
exist if it has no physical properties whatsoever, in which case it does not
explain any observations 'cause then you are
basically back to the problem of trying to explain how
consciousness comes about from combining all those
elementary particles to a brain, which is indeed a problem. But this is the standard problem that we have with consciousness. So do particles think? No, they don't. Okay, so this brings me
pretty much to the end, but I want to say a little bit more about why I wrote the book. I wanted to say that
physics is so much more than what we learn in school. So the way that a lot
of people are introduced in school to physics, it's about magnets or how batteries work or things rolling down in client planes or maybe nuclear decay, that kind of stuff. And I did a quick Google
search for for physics icons. And this is what came up and this, this gives you pretty much an overview how people think of physics. And I think physics is
just much more than this. It is our best tool to find answers to those big existential questions. And I've summarized
some of them in my book and I think I'll leave you with this. Thank you for your attention. (audience applauding)
This was both extremely entertaining and educational to watch, even for a layman such as myself in the fields of physics and theoretical physics. I'm going to have to give it a couple more watches to have the broad strokes of her speech fully sink in, but even so, Sabine made them as easy to understand as you can possibly make it. I also like how her using theoretical physics to prove that the past still exists, sort of washes away the theory some people have that there is no more past or future, only the present.
It also correlates nicely with the report that those Australian mathematicians and physicists made showing that time travel, both in general, and to the past, is mathematically and scientifically possible. It seems like the connecting tissue is slowly beginning to line up among the scientific community. The past still exists, and extrapolating from that, it is mathematically and scientifically possible to travel back to it.
If this line continues, and I hope it will, the next big topic to begin to be discussed among scientists and mathematicians will be the means to create a machine capable of transporting a person from one point in time to another. And that is when things will begin to become both very interesting and extremely exciting.
simple answer, yes.