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MARKUS KLUTE: Welcome to 8.20.

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Welcome to Special Relativity.

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And let me start by
wishing you all a happy New

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Year, happy New Year 2021.

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I'm pretty sure
this is going to be

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an exciting year with
a lot of changes ahead

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and a lot of exciting events.

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My name is Markus Klute, and I
will guide you through this IAP

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lecture on special relativity.

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This is very likely my
favorite class at MIT, A,

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because it's IAP, and
we start a new year.

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There's a lot of
excitement in the air.

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And we have a chance to focus
for this one month of January

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on this specific subject.

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B. I have a chance to introduce
a man, Albert Einstein,

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through a discussion
of his physics,

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through discussion
of him as a person,

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and also through a discussion
of the historic context

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in which he developed
special relativity.

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And C, if this is
the first time you

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encountered special relativity,
it will blow your mind.

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And it actually is quite
fun as an instructor

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to do a little bit
of a transformation

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in your understanding
on physics.

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So let's get started with a
quote, with an Einstein quote.

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I have a number of those
as we go through the class.

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This one here is really kind
of the theme of the class.

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Let me just read this to you.

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"It is not the result
of scientific research

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that ennobles humans and
enriches their nature,

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but the struggle to
understand while performing

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creative and open-minded
intellectual work."

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It is really the struggle with
the ideas, really the trying

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to get understanding which
ennobles humans and enriches

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their natures.

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And let me add here that,
through your own work,

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through your own mind,
you can transform

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yourself and your understanding
of physics in general.

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This first video and
this first lecture

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will mostly be concerned
with organizational topics.

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So I'll lay out the
schedule of the class

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and also how you get a
grade, of what kind of PSETs

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we have in mind and so on.

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Let's get started.

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So I introduced myself
already-- again, Markus Klute.

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You can reach me by email.

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It's klute@mit.edu.

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We have a graduate TA, Justin.

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His email is given on
the slide, as well.

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And then we have,
too, graders and TAs--

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Mohit.

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Zach, YuQing, and Stephen.

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Those four will guide us
through the class, as well.

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And especially when we
go into breakout rooms

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in the live class, they will
help you in the discussion.

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The class hours are from
3:00 to 4:30 PM on Zoom.

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And you can-- I encourage
you to join the class,

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to participate, to be
active in the class.

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But you will also be able
to get through the material

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through recordings.

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I will not record
the live class,

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because I want to encourage you
to be just as open as possible.

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But I pre-record the class, and
after the class time is over,

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I'll upload those videos
for your reference.

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And also, if you live in
a different time zone,

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you have a chance to
listen to the class.

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Office hours will be Tuesday at
9:00 AM and Friday at 5:00 PM.

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Tuesday, you reach me, and
Friday you reach Justin.

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Will set up a Slack
workspace which

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we use for our
internal discussions

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with a teaching staff.

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But there's also
going to be channels

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for you to discuss
PSETs as channels

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we discussed for physics.

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And there's going to
be a channel, which

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will be important when we
go to the exam discussion.

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The expectation is that you
spend about 30 hours a week

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during IAP.

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Some will find the PSETs
very straightforward

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and quickly to do.

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Others will need more time.

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So not a-- don't set your
stopwatch for 30 hours.

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That's just an average guide.

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I will evaluate you at
the end of the term,

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and I will use this metric here.

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50% of your grade will
come from the homework.

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There's going to be five
different homework assignments.

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There's going to be two
midterms with 15% each and one

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final that's 20%.

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If I do the math correctly,
this should lead us to 100%.

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You earn an A with 90%, a
B with 75%, a C with 60%

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or higher, a D
with 50% or higher,

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and then a failing grade
with less than 50%.

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So all lectures will be on Zoom.

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You'll find the Zoom
links on the Canvas page.

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And you probably
found this already.

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Otherwise, you wouldn't be
able to find this video.

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And again, as I was
saying, the recordings

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will be available after class.

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This is the schedule.

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Let me start by
explaining this picture.

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That's Little Thomas here
and then a German ICE train.

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This class-- the way
I look at this class

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is that it's a
train which is just

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leaving the station right now.

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And it will very
slowly pick up pace.

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But you want to make sure
that you stay on the train

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and you don't jump off, because
this will, once it's picked up

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its pace, will be a
fast moving train.

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And missing a few
days in IAP will

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cause you to have
trouble following

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along with the material.

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We'll start today with
this introduction.

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Tomorrow, we have a
very interesting lecture

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by David Kaiser.

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This is the only one where we
actually record the live event.

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So we record the Zoom session.

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And then the rest will
unfold, I was about to say.

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You find this red block here.

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Those are our midterms
and the final.

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On those days, there's not
going to be a live class.

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But I will make the final--

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sorry, the exam available
for about 24 hours.

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You should not spend
more than an hour,

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maybe an hour and
a half on the exam.

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And then submit
once you are done.

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The exams are open book
in a sense that you

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can look at the
textbooks, and you can

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look at the course material.

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But you are not supposed
to do an online search

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for the solutions,
and you're also not

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supposed to discuss
with your peers.

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You can ask clarifying questions
on one of the Slack channels,

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and we will be happy to answer
as quickly as we see them.

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But again, this is an evaluation
of your own performance,

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and you should submit
your own performance.

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The PSETs are
different in a sense

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that I encourage that you
guys build small groups

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and work on them together.

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Each PSET then has to
be submitted by you

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as an individual, meaning
that I don't want to see

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copies of PSETs of other folks.

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I want your own answers
in your own words

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to the questions we pose.

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Very important day in January
is Martin Luther King Day,

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and IAP gives us all a
little bit of a breathing

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room and extra free day.

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And you see that
there's going to be,

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after the discussion
at the very end,

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after the final, a special
lecture where I introduce

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the topic of general
relativity, which is not

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part of the core
content, especially

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of this special
relativity class.

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Textbooks-- I will not really
follow the textbooks line

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by line or chapter by chapter.

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But I encourage you-- and
I give you an outline--

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to read them, especially
the first two ones.

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The first one is by French.

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The second one is by Resnick.

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The first one is the
former MIT professor.

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You are supposed to read
this book cover to cover,

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and I give reading
assignments on this.

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Resnick has a lot of good
examples and problems,

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and we will focus on the first
four chapters of that book.

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There is a lot of literature
out there on special relativity,

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as a slew of
textbooks available.

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If you have one at
hand, you can also

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use that and find the
relevant chapter in there.

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I give you one extra
book here, which

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is nice because it is
an excellent explanation

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of the mathematics involved.

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If you're more
inclined to course 18,

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that might be an interesting
textbook for you.

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Again, there's
many, many resources

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on the topic of
special relativity,

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and I'll point out
a few as we go.

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In addition to the textbooks,
I give you a number of papers--

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for example, the paper
in which Einstein

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explains or
describes the concept

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of the theory of
special relativity.

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And there's a few others
which I'd like you to read.

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They're interesting because
they introduce the physics,

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but they're also
interesting as they

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have been written more than
100 years ago in a slightly

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different language than
we would be using today.

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And Einstein,
specifically, doesn't even

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write papers the way
other people wrote papers

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at the time.

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He had his own style
in writing papers.

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And we will see that.

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So here is the reading
assignment week by week.

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We start in week one by Resnick
Chapter 1, French Chapter 2.

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There's two papers, the
Michelson Morley paper

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and the Einstein paper
on special relativity.

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And then we go on as
we go through IAP.

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Your homework schedule is here.

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I hand out PSET number
0 today, and I'll

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explain it on the next page.

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This is a PSET which allows--

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I mean, this is
a PSET which will

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keep you busy for the
entire month, or most of it.

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The other PSETs are shorter,
and they are more pointed.

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And you get the
PSET, you work on it,

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and your hand in the solution.

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And by the time you have
done that, the next PSET

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rolls around.

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I would use the PSET
load a little bit,

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because I want to acknowledge
the fact that it will be harder

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for you to work in teams.

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I still encourage this.

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You find yourself on Slack.

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You find yourself
on Zoom channels.

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Some of you might
have housing together.

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I really encourage you guys
to discuss the physics.

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There are some really
difficult concepts

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which just need you to think
through and to talk through.

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And the talking through best
happens with your peers.

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And you will see that that will
be very beneficial, especially

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when it comes to the PSET.

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But here is homework number 1.

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I've done this now a few
times, and I really, really

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enjoy the solutions
given by the students.

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So this is a creative project.

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You have basically almost
all of IAP to hand it in.

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And the idea is to be creative
around a topic relating

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Einstein, or/and the theory
of special relativity.

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The project might be a video.

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It might be a poem.

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It might be a musical piece,
artwork, animations, a game,

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a structure--

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you name it.

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What I really want is that you
take something you do very well

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and combine it with the
topic of this class.

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I want you to take
something where

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you are very familiar with where
you are feeling comfortable

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and then enter this new
topic, this new topic

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of special relativity.

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I will rate it based on your
creativity, on the quality,

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and on your effort.

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And again, please hand
this in by January 22.

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I really encourage you to
not wait to the last minute

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to start working
on those topics,

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those creative projects.

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They always take a
little bit more time

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than you might expect.

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This class will have an
interactive component.

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And we will use breakout rooms
for discussions and smaller

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problems as you would be doing
in the classroom, as well.

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Here is the very first one.

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People who are taking
this class asynchronously,

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I encourage you to stop here
and work through the problem.

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And then look at the
solution afterwards,

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or look at the discussion
of the solution afterwards.

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So this first Gedanken
experiment, thought experiment,

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is about the topic
of relativity.

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And you want to
first understand what

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that is, what relativity
is, before you discuss

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what special relativity is.

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So imagine you wake up
inside a room with no windows

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and one locked door.

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You checked.

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You make sure that
the door is locked.

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You cannot get out.

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You cannot see outside.

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Looking out around,
you see a table

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with a number of items on it.

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There's a desk lamp
plugged in and turn on.

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There's a tennis ball.

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There's a bunch of string.

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There's a pitcher of water.

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There's a cup.

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There's a candle.

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There's a box of matches.

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And there's a music
player with headphones.

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A skateboard and a wooden
stool are also in the room.

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The music player has
a sign on it saying

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turn it on for instructions.

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So you do.

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You're told that you are
in a specially designed

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vibration-proof and noise-proof
train car [COUGH]---- sorry--

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on a set of straight
and level train tracks.

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Your task is to use one or
more of the items in the room,

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perhaps in combination
with each other,

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to determine whether the
train car is stationary or is

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moving on the tracks.

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There's a 30 minute time
limit on your test or tests.

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And you cannot destroy or
you cannot modify the walls

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or the floors or the
ceiling of the car.

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That is not permitted.

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So the question to you is, can
you think of some creative way

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to use the items that might
indicate whether or not

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you are moving.

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Think about this and discuss
in your breakout rooms--

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that is, for the
live session here.

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Again, I want to encourage
you to stop and to think

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about a solution.

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Can you think about a creative
way to work with this?

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The typical time is
about 10 minutes.

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You might think about it.

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You might want to
take some notes.

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All right, the answer is
you cannot figure it out.

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Every reference frame
by itself is inert.

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You cannot figure out whether
or not you are in a moving

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or in a stationary
reference frame.

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And as long as you
cannot feel vibrations,

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or you hear the sound, or
you have some other internal,

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external indication, you will
not be able to figure out

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whether or not the room
is moving with a constant

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velocity.

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You will be able to feel
or measure accelerations.

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And so now you could
argue that since the train

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track is on Earth, and
the Earth is actually--

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since you are on Earth,
and if you're moving,

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you would be able to feel
the rotation of the Earth,

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there might be a way
to figure this out.

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But that will be
very, very hard to do.

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So the answer is you cannot.

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You cannot distinguish one
reference frame from another.

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You don't know what an
absolute velocity is.

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So another way we will
interact in this class

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is through concept questions.

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So here, concept
questions are meant

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to give you a little
bit of a checkpoint

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to encourage you to think
about what I just explained

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in a video or in the
class and to stimulate

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some sort of discussion.

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Sometimes you will use contact
questions in breakout rooms

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for the discussion
part sometimes

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you just use Zoom features
in order to figure out

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what the answer is.

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But besides the technology,
those concept questions

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are really for you to figure
out whether or not you just

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understand the concept.

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So again, I encourage
you to pause the video

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to think about the
concept question

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and then move on
with the answer.

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Here's an example.

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A new Star Wars
movie came out, 2019.

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And I ask you to pick the answer
closest to your level of Star

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Wars expertise.

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I saw the movie, and I consider
myself a Star Wars fan.

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00:17:38,020 --> 00:17:42,610
I saw the new movie, but I do
not know much about Star Wars.

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00:17:42,610 --> 00:17:45,130
I heard about Star Wars, but
I didn't see the movie yet.

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00:17:45,130 --> 00:17:47,480
Always liked Star Trek better.

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00:17:47,480 --> 00:17:47,980
What?

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00:17:47,980 --> 00:17:49,510
Star Wars?

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00:17:49,510 --> 00:17:52,690
OK, so very straightforward--
here I would give you

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an option--

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1, 2, 3, or 4.

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00:17:54,910 --> 00:17:57,670
You collect the answers,
and we get some feedback.

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00:17:57,670 --> 00:18:00,580
This is obviously-- there's
no right answer here.

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00:18:00,580 --> 00:18:02,500
There can be concept
questions where there

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00:18:02,500 --> 00:18:04,310
is a right and a wrong answer.

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00:18:04,310 --> 00:18:06,520
And again, for you,
this is supposed

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to give you feedback on how
well you understood the concept.

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00:18:12,220 --> 00:18:14,380
All right, before we
close this first video,

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I want to introduce
players, Alice and Bob.

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00:18:17,970 --> 00:18:22,800
We will have, often,
discussions of reference frames.

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Typically Alice or Bob are
in one reference frame.

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And then the other person is
in the other reference frame.

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I want you to think about
those Star Trek figures.

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We will use spacecrafts.

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00:18:35,520 --> 00:18:37,950
We will use light--

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00:18:37,950 --> 00:18:42,220
so phasers or light pistols--

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in order to demonstrate the
impact of special relativity

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and understand the concepts.