Kind: captions
Language: en
[Applause]
Can we can we really touch something so
that I can touch the camera?
The question of can we really touch
something is a great one. Well, let's
say we have two electrons. I imagine
what we mean by touching is that they
come in and they actually physically
touch. Now, one of the problems is an
electron actually has zero size as far
as we can tell, no volume. So, these
would be infinitely scaled up. So, how
do the electrons actually interact with
each other? Well, they interact by
exchanging a particle. In the case of
the electrons, it's a photon that they
exchange. So, as they come in, a photon
is passed from one to the other, which
changes the momentum of both of them and
pushes them off. So, they never really
have to touch in order to interact with
each other, to exchange that particle,
and therefore change their momentum and
change directions, experience a force.
So, I guess what do we mean by touching
something? Every time we touch
something, we are exchanging force
carrying particles with it. And that is
touching. If photons are both quant of
light and the force carriers of the
electromagnetic force, does that mean
that photons propagate magnetic fields?
And if so, why can't these photons be
seen? That's because the photons are not
real photons. They're virtual. Now, this
is a bit of a problematic topic and one
which I hope to address in detail in a
coming episode. The basic idea with
virtual particles is you can't detect
them. There are particles that are there
but you cannot directly detect them and
they may not obey all of the laws that
we force real particles to adhere to.
For example, there's the Einstein energy
momentum relation E^2= M C ^2 + P ^2 C
^2 and a virtual particle doesn't
necessarily need to obey this equation.
So you can't really detect it because if
you did it would have to be a real
particle and then it can't disobey those
equations like that. So, this is
something that I will delve into in a
future episode. Who are your top three
most inspirational scientists? I'm going
to take Einstein, Fineman, and Tesla.
Who are your most inspirational
scientists?
Hey, Derek. I guess a question that's
been on the minds of a lot of us for a
while now is who would win a chin-up
competition between you and Henry from
Minute Physics?
Now, I wish this was a hypothetical, but
we actually did this on the tube in
London. So, roll the tape.
[Music]
Wow, look at
[Music]
me.
This is impressive.
[Music]
Yeah, do that.
Keep going, guys.
Very good, loser.
That was nice. You're a champion.
How you feeling?
So tired.
I thought it would be Henry. That guy is
ripped. So at school, they say atoms
want to have their outermost electron
shells full and will willingly become
ions in order to achieve that. Well,
why? And why do the shells have the
electron holding capacity of 2 8 and 32
and so on specifically? Let me deal with
the electron shells first. See, if you
accept that electrons are not only
particles but also waves, then if they
are waves bounded to a nucleus, that
means that they must be standing waves.
So you may be used to standing waves on
a string. They don't seem to move
anywhere. They just wiggle back and
forth. Or you can have standing waves in
two dimensions on a plate. And what you
notice is that these standing waves take
on particular stable patterns. So bound
electrons are just standing waves in
three dimensions. And the mathematical
solutions are called the spherical
harmonics. Because of the number of
stable configurations you can have with
growing amounts of angular momentum,
there are different amounts of electrons
which can fit into every state. And that
goes with Pal's exclusion principle
which says no two electrons can have the
same state because they're
so pointing
electron waves and there are only
certain of them which are stable which
are possible which you can see in
analogy to say vibrations in a plate. So
why do atoms want the outer electron
shell to be full? Well, this kind of
minimizes the energy state of the whole
system. So let's say you had two atoms.
If you actually removed the electron off
one atom and stuck it in the other, so
that they both now had full shells, you
would find that the total energy is now
lower than it was before when the
electrons were in their previous
configurations. So the point is it's
just like a ball rolling down a hill.
It's that everything in nature wants to
go to the lowest energy state. Why are
the available frequencies of light
continuous? I keep hearing that atoms
absorb and emit photons of particular
frequencies which correspond to the
energy levels of their electrons. So
where do all the other colors come from?
Okay, it's true that atoms emit
particular colors due to electrons
jumping between certain allowed orbits
around them. But we get different
frequencies of light when these atoms
bind up into molecules or even solids or
when they form plasmas because then the
charges are flying around all over the
place. And in those cases, there's no
longer these clearly defined energy
levels for the electrons where they can
jump and only produce certain distinct
colors. Then there are whole bands of
electron energy levels. So we can get a
a real range of colors. So that's what
we see from the sun or from hot solids.
So that's why we get a continuous range
of frequencies because the electron
bands of energy allow virtually any
transition.
Derek, can I get a Veritassium shirt so
I can look nearly as cool as you?
It's funny you should mention that,
Gray, because Veritassium actually now
has a t-shirt. So if you want to get
one, you can click on this shirt. Go
ahead, click on it or click on the link
in the description. For your viewers
interested in pursuing a science career,
what field do you think is going to be
the most exciting in the coming
centuries and why? Look, I can't say I
know what fields of science are going to
be important in the coming centuries,
but at least in the coming decades, I
would put my money on genetics. You
know, if you think about the human
genome project that took about 10 years
and a billion dollars to to sequence one
human genome and within the next couple
years, you should be able to do it in a
week for a hundred bucks. So, the pace
of growth is simply extraordinary in
that field of science. And that's why if
I were going into science now, I might
select that kind of field. Have you ever
downloaded a book from audible.com? I
have actually downloaded a book from
audible.com. And I was listening to it
on my most recent trip, which was handy
because I was on this plane that didn't
have an entertainment system and I was
also listening to it in the airport. And
I found it really a good way to pass the
time. So if you're interested in
downloading audiobooks, then you should
probably try audible.com. And I have a
book to recommend to you. It is Richard
Dawkins book, The Selfish Gene. I read
this a few years ago and I found it
really enlightening, but I have a bit of
a spoiler alert. Uh, well, not really a
spoiler, more of a clarification on the
title. I mean, it sounds like a book
about a gene for being selfish, but
that's not what it's actually about.
What it's about is the fact that genes
themselves act in selfish ways. And this
I found a kind of enlightening
revelation because if the genes are
acting selfishly then the organism can
act altruistically
if you get what I mean. So if you
haven't read that book or listened to it
you should definitely check it out. And
if you want to download it for free you
can just go to audible.com/veritassium.
You know I really want to thank
audible.com for supporting me in this my
500,000th
subscriber video. It really means a lot
to have their support so I can keep
going and hopefully get another 500,000.
[Music]
One last question, Derek. I'd like to
know how, obeying the laws of physics,
you ever manage to put these jeans