This is StarTalk, I'm your
host, Neil deGrasse Tyson,
your personal astrophysicist,
and today's episode
is Cosmic Queries -
The Out There Edition.
We're talking about
not just astrophysics
but the extremes of
astrophysics - in space, time,
and dimensions.
While I have some
expertise on that topic,
I don't have all the
expertise necessary
to pull this off, so
we called in my friend
and colleague Janna Levin,
Janna.
- Neil, hey!
- Okay, thank you for coming.
- I love being here.
- Not your first rodeo.
- Yeah, not my first rodeo,
but I haven't been in your
office in a long time.
- Okay, well,
- It's fun to see it.
- It's gotten messier.
- Yeah.
- Just so you know.
- In kind of a good way,
almost like a, I don't know,
curatorial way. (laughing)
- A curatorial way.
- And helping me bring
some levity to this topic
is the one and only Harrison
Greenbaum, Harrison.
- How you doing?
- Welcome.
- I do think we need to
get Marie Kondo up in here.
- Oh really? (laughs)
- To see which things spark joy.
(all laugh)
- It all sparks joy.
- There's a
conflagration of joy.
- Get the hell out of my office.
- Exactly.
We'll barricade,
we'll barricade it.
(all laugh)
- So you're a comedian
and a magician.
- Yes, absolutely.
- That's crazy,
dude, stay here, I don't
want you to disappear.
- Classic double threat.
- And don't make my guest
disappear today, right?
- Absolutely.
- Okay.
- I use my powers for
good, I'm a good witch.
- [Neil] And so we'll find
you at HarrisonGreenbaum.com.
- Yeah absolutely.
- Your tour schedule
and everything.
- And also maybe Comedy
Central will book me
if this is my website dot com.
Which I did register.
- Oh really.
(all laughing)
We all froze for a second.
(laughs)
It's a very long domain,
for some reason
it was available.
- There was a real beat there.
- Yeah (laughs)
- So Janna, you're an expert
on the large scale universe,
on black holes, your recent
book was Black Hole Blues,
was that?
- Yeah.
You know you've said it
better than anyone ever.
I once got you to say the
whole title which you might not
remember was Black Hole
Blues and Other Songs
from Outer Space,
and you did your
best DJ voice, Neil.
I can't... I don't even
know if I have it recorded.
- [Neil] Really.
- Yeah.
- Let me try it again.
(Janna laughs)
The Black Hole Blues ,
wait a minute,
- [Janna] and Other
Songs from Outer Space
- And other songs from outer--
The Black Hole Blues and
Other Songs from Outer Space
(laughing)
does that work for ya?
- Really working for me.
- You can put that on
your ringtone. (laughs)
- Exactly.
- I'm a big fan of
the blues in general
so I was enchanted by the title.
So Harrison, if you remember,
this is also not
your first rodeo,
but you're not a
regular on the show.
For Cosmic Queries,
we solicit questions
from our fan base
through all the social
media channels and then some
and you the co-host
are the only one
who's seen these questions.
I haven't seen them,
Janna hasn't seen them,
and you're just gonna read them,
and Janna and I will
try to answer them,
and if we can't answer
it we'll just say,
I'll say I don't know, she's
not gonna say I don't know
'cause this is--
- Yeah I might just
make some stuff up.
(all laughing)
- Make some stuff up.
- Who's gonna call me out on it?
- I will call your stuff out,
maybe I'll call you out on it.
- By then I'll be
home. (laughing)
- So Harrison, so what
do you have for us?
- Since you haven't seen these
I could just be making these up.
- That's true, too.
- That would be hard
though, I think.
Yeah, yeah, alright.
- Alright so we'll start with--
- We got goood people who
listen in our stuff so.
- The first question says
how do you make
Harrison a regular?
(all laughing)
I didn't know if that
came from my mom.
Definitely on the G.
No, so here's a
Patreon question,
- [Neil] Patreon.
- Yes.
- Oh so you out of
all those questions
you went and found the Patreon
question and put it first.
- Absolutely, every time.
- That is kissing
ass, you realize this.
- Gotta do it.
- Okay.
- Zachary Spradlen from Patreon,
and thank you for supporting.
The question is, given your
vast knowledge of physics
I'm sure they're talking to me,
(Neil laughing)
What are your thoughts on
a holographic universe?
Would 100% empirical evidence
of a holographic universe
change how you behave
on a day-to-day basis?
Imagine if we could
access the universal
holographic database.
- [Neil and Janna] Ooh.
- That's a good one.
- That's like a three-parter.
- Now Janna, I've tried to
fully understand the holographic
universe and I only kind of
skimmed the surface of it
so if you have a deeper,
- It's pretty spectacular.
- If you have a
deeper sense of this
I would totally wanna know.
- Yeah, it's not something I
specifically have worked on
but I've paid very
close attention to it
in the hopes that one day
I'll have a good enough idea
to actually jump in the fray.
So the way that--
- Just to be clear, so
when you do your work,
you're a theorist, and you're--
- [Janna] Very pen and
paper, old fashioned.
- Old fashioned, wow.
- [Janna] Totally old
fashioned, pen and paper.
- So you're really
cheap. (laughing)
You're a not
expensive scientist.
- If you want to
give me a grant,
I can do my research.
- Couple thousand dollars.
- Seriously, lowest level
in terms of equipment
and supplies.
- I think somebody'll
buy you a Mac Book.
I feel like somebody out there--
- At least an iPad.
- Yeah.
- And that's only to
check my social media.
- A very large iPhone,
we can get this done.
- We, you and I got
this, we got this.
So just so people know,
you're a professor
of astrophysics
at Barnard College
at Columbia University, which
is right up the street here,
which is great.
- Right up the street, yeah.
- Okay, so go on.
- So--
- [Neil] The
holographic universe.
- So a hologram, the
whole idea of a hologram
is that you really have
two-dimensional information
but it creates the illusion
of being three-dimensional.
That's just what
a hologram means.
- Yeah 'cause when
you look at it,
like your credit card
might have a holographic
bird on it--
- [Janna] Right, but it's
a two dimensional object.
- My binder in middle school.
- It works in two dimensions
because it's flat.
- It's flat, but it looks like
a full three-volumed thing,
okay, so the reason why
these physicists coined it
holographic is precisely
because they're imagining
that all of the information
that is required
to understand the
universe can be encoded
on just a surface as opposed
to in the full space.
So for a black hole this arose
because if you
look, a black hole
doesn't physically have
anything at its surface,
but we imagine the event
horizon as a surface,
the region beyond which
no information can escape.
And the idea was that
everything about the black hole
that all the
information a black hole
could possibly contain is
equivalent to the amount
of information that can
be packed on the surface
and nothing more
and you cannot, and they've
proven this over many years,
back since Hawking, you
cannot have more information
than the information you
can pack on the surface.
And the reason
why this becomes--
- You're saying
more information can't
get into the black hole
than can be stored on the
surface of the event horizon.
- Yes, that you can prove
that the information
content of the black hole
scales like the surface area
of the black hole,
the event horizon,
and not like the volume.
And so the idea would be,
well we could maybe
make an object--
- He shook his head yeah,
get that calculation.
- I used to have those
hologram stickers,
of like, cats,
does that get me anywhere
close to understanding?
- So you know it's one thing
to kind of think about that
but then it took really
years before people
like Leonard Susskind
started saying,
"Oh wait--"
- Is he a physicist at Stanford?
- He's a physicist at Stanford
and just an incredibly
creative thinker.
- [Neil] Larry Susskind.
- Yeah and great New
Yorker from the Bronx.
He was a--
- Bronx in the house
- Yeah.
- BX.
- Bronx in the hologram.
- I love Lenny's accent.
- We brought him a hat up there
I don't know if it
shows up in the thing.
- He's got that tough
guy accent still.
So he really started
to think about this
like let's say I try
to have information
that actually scales
like the volume
like so that would be
a lot more information
than you would think you
could pack on the surface
and you can prove that,
well then you'd just make
a black hole, and we
know about black holes
fundamentally that you
cannot have more information
in the black hole than you
can put on the surface.
- But what does it mean to
put information on a surface
that does not exist?
- That's very subtle,
so it's really the idea,
there's two ways of saying it.
One is to just say, oh,
the information content
of the black hole has been
proven to scale like the area
and then the string
theorists started to think
well maybe that physically
means it's like there
on the horizon,
- [Neil] The event horizon.
- The event horizon, that
as something falls into
the black hole, it might
appear to the poor astronaut
that thinks they're
falling into the black hole
that they have crossed
the event horizon
and met their fate
in the interior
but to us on the
outside it may appear,
and this is a string
theory suggestion,
that it's actually physically
smeared on the outside,
in the quantum string
states that are permitted
on the outside, and that
it never gets inside.
- So what about the
fact that if I watched
someone fall into a black hole,
I see their time slow down?
And at the event
horizon it has stopped.
- [Janna] Exactly.
- So can we say that all
this stops at the black hole
as far as I can see?
- I mean it certainly is
driven by some of those early
confusion about that.
So it does seem, as far as we're
concerned it never crosses.
But to the astronaut themselves,
- They just fall straight--
- they sail right through.
So it's literally suggesting,
like quantum complementarity
created this whole,
there are two things
that seem incompatible that
can exist at the same time.
It's literally suggesting that
the astronaut both falls in
and does not.
- And is smeared on the surface.
- And is smeared on the
surface, but there's no single
person in the universe
who would be able
to experience both things,
so no single person
has a contradiction.
Woo, I say it's--
- When you talk about encoding
information on the surface
do you mean like the way like
there's a California tattoo
on Adam Levine?
(Janna and Neil laughing)
Where we know he's
from, California?
- He's only tattoos on
the surface, it just--
- That's all he is,
there's nothing inside.
- It looks like a
three-dimensional body
but it's really
just skin tattoos.
- Okay.
- So tell me something,
if I think people
freeze at the surface,
then they're not living out
their lives, we're
living out our lives,
how could we be in the,
every hologram I've seen,
it's a frozen image, it's not,
or it repeats in
some trivial way.
- So that's what we would see,
we would see them freeze.
- But I'm not frozen, so
how can I be a hologram?
- So oh, I see what
you're talking,
so it would be--
- Wait, wait, I don't
think I'm frozen.
(Janna and Harrison laughing)
- So you--
- It's like the end of the Mary
Tyler Moore opening credits
where she like
freezes with the hat?
- Oh she freezes there
when she flips up her hat.
- Right, is that what
we're talking about?
- Actually, how old
are you? (laughing)
- I have no age.
- You're just a fan
of Mary Tyler Moore.
- Yeah.
- She was off the air since
- We're at the edge of a
black hole so my life is just
- Since 1872 that
show's been off the air
I just want you to know.
- So I would say the idea
that holograms are frozen
is just a technology problem.
You certainly could
make a hologram
that was updating the
information on the surface
and therefore moving in time
so it doesn't have to be
frozen to be a hologram
but it does have to
be two-dimensional
and nonetheless appear
three-dimensional.
- Why can't we be a
three-dimensional hologram
of a four-dimensional
space? That's good, huh?
- Um, well, that's not bad--
- That was very good.
- Not bad, Neil.
- If a hologram is
one dimension less.
- Yes, it could be the case
that there's definitely--
- And are we four dimensions?
- Well because
- Three spaces in one time?
- Yeah, so there...
- [Neil] Don't go back
on us on that one.
- I'm not goin' back
on you on that one
but there is some confusion
about that time dimension
but you know,
- [Neil] Whether it behaves
as a space dimension.
- It clearly does to some extent
- Whether it is a
full-blooded space dimension.
- But to some extent it doesn't
because I can turn
left and right
- in space
- but I can't, in space,
- I don't think my
car has that setting
(Janna and Neil laughing)
but I can't go forward and
backward in time, right?
So I can't do both
directions in time.
- You have mobility
in space coordinates
and not in your time.
- And I can see things
in both directions.
I can see something to the
right, and I can see something
to the left.
I can see something in the
past, whereas all light travels
to the universe and gets to me,
but I can not see
something from the future.
- So we are prisoners
of the present,
forever trapped between
a past we cannot access
and a future we cannot see.
(Janna laughs)
- Neil, you're such a poet.
- I think that's the new
opening to the Twilight Zone.
(all laughing)
- [Janna] Cue the music.
- Okay so that's cool, so if we,
so let's get back
to the question,
if we know.
- [Janna] This
one question could
keep us busy the whole time.
- A hundred percent, if we
are a hundred percent sure
that we are a hologram,
should we behave
any differently?
And who are we a hologram to?
- Yeah so this is--
- On whose black
hole surface are we?
- Right so then well so
people have a harder time
understanding holography
in the cosmological context
moving away from the black hole
but the idea is that a
black hole is the terrain
on which we learn
fundamental thinking,
so we should use the lessons
that we can only learn there,
the evidence that
only exists there,
to understand the
whole universe.
- As a cue, as proxy.
- Right so then we turn
around and we say oh,
the universe is
expanding so rapidly
we have a cosmic horizon.
- [Neil] We do.
- We do, there is a region
beyond which we cannot see
as long as the universe
expands at this pace
and the light can never get
to us, race though it might,
'cause the expansion of the
universe will exceed it.
- So we are analogous
cosmologically to a black hole.
We're inside it's event horizon.
- Yeah it's like an inverted
one and we're inside
the event horizon, and
there's stuff beyond it
that will never know about us
and we'll never know about them
and so can we make
a holography of that
and then yes, can I make a
holography of just you and I?
But you see we have so
much less information
than the maximum we
could pack on us,
that that's why
we haven't tested
whether or not we're
holographic animals.
You see, holography requires
a more sophisticated thing
than just, like printed
words in a book,
which is not holographic,
but it's way less than
the maximum amount
of information
that you can pack.
And the hologram is an
example of packing a lot more,
right?
So if you made a human
being that was packing
the maximum amount
of information
that they possibly could,
they would turn into
a black hole. (laughs)
- [Harrison] Or they'd have
a really full backpack.
- Yeah, so holography
doesn't say
you can't have things
with less information
that are just not, you
know, as extraordinary.
It just says that's the
maximum that we can have
and so it's all an illusion,
we really are two-dimensional.
- You're flippin' me
out a little bit here,
so let me just say,
and I'm an astrophysicist right?
- Right.
- So why did you all of a sudden
without anybody's permission
in this conversation
equate matter with information?
'Cause when I think of matter,
the concentration of
matter, as a star guy,
I study stars, you
pack in the matter,
and you get a black hole.
Now you're saying you're
gonna pack information.
You get a information
black hole.
I mean is that the same thing?
- I think that the
shift that I'm feeling,
and that I'm learning
from other people as well
is that matter is
just information.
So what does it mean to say,
an electron is matter?
What we mean is it
has a certain charge,
it has a certain span,
- property.
- It has a certain number
of quantum properties,
and those quantum properties
qualify as information.
- And it completely
defines what the thing is.
- And it completely, there's
no such thing as an electron
that's a little bit heavier,
or a little bit lighter,
spins a little faster
or a little slower,
has a little more charge
or a little less charge,
there's no such thing.
- Every electron is identical
to every other electron.
- Yeah, identical.
There's literally
no history to it
- It's like all the Kardashians.
(all laughing)
- Which one is that one?
- Yeah the only thing
that I need to know
is its position in space.
(Neil laughing)
- Exactly.
- So the idea there is
that the electron is simply
the collection of
information about it
and that is its identity
and so then we start to think,
well what else does it mean
to be physically real is
just that list of
quantum properties.
- [Neil] Wow.
- So I think that
the shift is to say,
look it's just math
and information.
And we gotta stop thinkin' so
concrete you know, feelin'.
- Like physically.
- Like, we know that
this is an illusion.
I can't put my hand
through your leg
even though we both know
it's mostly empty
space, both parts.
- We are mostly
empty frickin' space.
- Yeah, voids, two voids.
- That's the secret
to one of my tricks,
I won't tell you which one.
- 'Cause you're also
a magician, right.
- [Harrison] It's all quantum.
- There's a famous comment,
I'm gonna paraphrase it
and it might be apocryphal
but it's great anyway,
Rutherford, was it
Rutherford who discovered
that the atom was empty?
I think it was Rutherford.
- Yeah I mean wasn't he
doing the nuclear stuff?
- He did the gold
foil experiments.
So what you do is you get
a really thin gold foil,
like aluminum foil,
this is gold foil,
hammer it really thin.
- That's what I've seen Trump
wraps all his sandwiches in.
- I was gonna say, aah!
- Trump gilded everything.
So then you hang it there
and you fire particles at it
and you ask, how often does
a particle hit a gold atom
and how often does
it pass through?
'Cause you make it
really, really thin,
and it turns out most particles
pass right through the foil.
- [Janna] No damage done.
- No damage done, not
deflected, nothing.
And he concluded
that most of atoms
are completely empty
space, and he's rumored,
the next morning, after
having contemplated this,
that he was afraid to
step onto the floor
getting out of his bed
- For fear of falling in?
- For fear he might
fall through the floor.
'Cause he alone on earth knew
how empty matter actually is.
- I figured that out by
looking at Republican heads.
(all laughing)
They're very empty.
- Reading their Tweets.
- Yeah exactly.
- So in astrophysics
there's something called
a degenerate state,
which is not a statement
about its moral fiber, but--
- I was gonna say most comedians
are in a degenerate state.
- Degenerate state has to
do with whether two atoms
or particles can occupy the
same state at the same time,
the same configuration.
And electrons, two
identical electrons
cannot be in the same
place at the same time,
they have to be separated.
And so there's a pressure
because they will not,
there's a limit to how
close you can get them.
And now based on
how you describe it
I'm thinking if you do that
you're putting too much
information in one place.
- Ooh that's an interesting
idea, look at you Neil.
So the Pauli exclusion
principle would be caused by
- An information--
- An information limit.
- Wanna write a paper on that?
- Let's do it, oh my God, I'm
gonna be up all night now.
- Let's do that.
- Ah, I love it.
- All of the degenerate states,
it's an information problem.
- I love it I think
that's a lovely idea.
We'll talk about that later.
- [Neil] We gotta take a break.
- Do I get co-credit?
(Neil and Janna laughing)
am I gonna be in a paper?
- Yeah the credits,
yeah Harrison made
us laugh during this.
During these paragraphs.
- Moral support, I
was the cheerleader.
- So when we come back,
more Cosmic Queries,
Out There Edition.
(futuristic music)
We're back, StarTalk,
Cosmic Queries,
the Out There Edition.
All parts of the universe
that are far away and freaky
and (laughs) we've got some
good expertise for that
in Janna Levin, Janna,
good to have you,
and of course Harrison.
- Great to be here
- So this is the second segment,
you're reading questions.
The first segment we got
through only one question.
- Yeah but it was a doozy.
- It was a doozy,
all about holograms.
So what else do you have for us?
- This is from Facebook,
from Nate Gadeoso,
and he said could the
entire known universe
be the result of a white hole?
- Ooh.
- [Janna] Ooh, you wanna try it?
- Ooh, ooh.
Well let me put white
holes on the map
and then you take
it from there okay?
So back in the 1970s,
when the mathematics
of black holes
was being explored
and formulated,
it might have been late
1960s, but it was not deep
back in the century, it was
like that late, if you will.
People noticed that the
equations that give you
a black hole have a legitimate
opposite solution to them.
So let me test, Harrison,
let me test your 9th grade
math knowledge, you ready?
- Okay.
- Okay what's the
square root of nine?
- Three.
- Okay so what's
three times three?
- Nine.
- Okay, what's negative
three times negative three?
- Also nine.
- So nine has two
solutions, doesn't it?
- Right.
- Right?
Square root of nine
is negative three,
- Plus or minus, yeah.
- Yeah, and positive three.
So we only gave
you one solution,
the solution you preferred,
but there's the dark
side, the negative side,
so some questions in science,
the mathematics of them reveal
that there are two answers
that are completely
authentic and legitimate.
And when people were
studying black holes
and the mathematics
of black holes,
a second, in
Einstein's equations,
a second solution emerged,
that was everything
a black hole is
except the opposite of that.
So things only ever
came out of this space.
And so it would be white,
if you were to look for it
in the universe.
So they said let's
look for these things,
and people thought maybe quasars
which are very bright distant
objects in the universe,
maybe those are the white
hole versions of black holes,
and then so we have a
white hole and black hole,
maybe they're connected.
And this was the
introduction of a wormhole.
Wormhole would connect a
white hole to a black hole.
Everything goes in the black
hole, comes out the other side.
So we looked for the
properties of a white hole,
quasars did not satisfy
those properties,
and we kind of gave up on 'em.
So no one's lookin' for
white holes anymore.
So that's the farthest
I can take it.
- Wait, so it is a
really intuitive idea.
- [Neil] Did I get
anything wrong?
I think I got
- No, yeah,
that sounds great.
It's very natural to imagine
so let's say everything
falls into a black hole
and you think, it goes where?
And that's the whole
crisis about the black hole
is not the event
horizon and all that--
- That's a thing,
the hole crisis?
(all laughing)
- The H, I dropped the W.
- The hole crisis.
- The word must have
gotten stuck in my head.
So the idea would be that
you can sew on a white hole
onto the interior
of a black hole
and it kind of makes sense
because these singularities
that people run amok
on the streets because
they don't want them
to exist in nature
and they probably
don't exist in nature,
and the singularities
are so problematic
that wouldn't it be better
instead of having
this infinite energy,
infinite curvature of space,
- [Neil] Infinite density.
- Infinite density,
literally a hole in space,
like the matter gets
there in finite time
and then what?
You don't know
what happens to it.
Sort of like a cut in space,
it's something where physics
breaks down, fundamentally.
So people had the idea well
let's get rid of the singularity
and sew the black
hole onto the big bang
which is also a singularity
and so you get rid of both
and you repair it in some sense.
- Do you think at the
center of the black hole
it births another universe?
- Yes, so that is really--
- See how casually
she just said that?
(all laughing)
Talk about inventing a
whole frickin' universe,
"Yeah, of course, you
get a black hole."
- Yeah whatever, so.
- I'm still stuck on the plus
and minus negative three.
- What I love the most
about that is it means
that the black hole, small is
it might be on the outside,
So let's say our sun
became a black hole
by some intervention,
'cause it wouldn't naturally
collapse to a black hole,
it's not big enough, but
if it were, it would be
only about six
kilometers across,
be a very small
object on the outside,
but on the inside it could be
as big as a whole universe,
so it's like Doctor
Who's TARDIS.
- I was about to say,
I was so excited,
I was like that really
sounds like a TARDIS.
- Yeah that's hittin'
geek buttons right there.
- It's bigger on the inside
than the outside suggests,
and one way it could be bigger
is it could be a whole big bang,
it could be a whole universe.
The reason that's sort
of fallen out of favor
is because there are
reasons to suggest that
if that were true the universe
would become very unstable
to these things.
Because if there's just
some random probability
for a black hole spontaneously
creating a universe
in its interior, it would be,
even though seemingly unlikely,
it would just be such a, what's
the word I'm looking for,
such a enormous
proliferation of them
that it would actually
make the world unstable,
and so it's sort of
fallen out of favor.
- We don't want that.
- It depends on who you ask.
- There's enough
instability in the world.
- I'm all writing this
for my new screenplay
called The White Hole.
- So some old
fashioned relativists
who only think
about space and time
still like the idea
- Relativist is someone,
an expert on Einstein's
Relativity Theory.
- Yes and studies
primarily space time.
And those who study
things like string theory
and particle physics
are more skeptical
about the idea because
their work seems to suggest
this instability.
So sometimes the counts
are split on this stuff.
It can--
- Could be a very
tense dinner party.
- (laughing) yeah.
- So what you're saying is
wherever there's a black hole
there's another universe.
- [Janna] If that's
the case, yes.
- So this'd be
like a Swiss cheese
in the higher dimensional,
- That's right,
but that universe,
okay so space and
time switch places
interior to the black hole
so while you're imagining a
universe which is spatial,
the black hole
would be in its past
and therefore inaccessible.
So it would look like the big
bang was solely in the past,
it wouldn't be a place you
could go to in the new universe.
It would be a time
in your history.
(Harrison laughing)
- We gotta take a
break, no (laughing)
- And they're just now
getting rid of CBD products
in New York?
Oh man, the timing's terrible.
- No, just if I repeat what
I think I heard you just say,
if you fall into a black hole,
the universe you came from,
you will see the entire
future history of the universe
unfold in front of you
in an instant.
- Yes, so the black hole's
bright on the inside.
- Bigger and brighter
on the inside.
(Janna laughing)
Yeah, there you go.
- Yeah.
- Alright gimme
another question.
- That's good, I just don't
wanna let any of the alt right
know about this white hole,
'cause they'd be
like see I told you
there's another one.
Alright, what's your, this
is from a Patreon candidate,
contributor, Frank Kane,
which I think, is he related
to Bob Kane?
That's the guy who made Batman.
What's?
Probably not but
Batman shout out.
What's your take?
- [Neil] Probably not.
- But if a whole universe
can fit in a black hole.
- [Neil] Plus he's The Batman.
- That's your.
- [Neil] The Batman, right?
- What is your take
on negative mass?
I've read that if it exists
we can hold open wormholes,
travel backward through time,
make a warp drive and
all sorts of crazy stuff.
If the math says
possible do you think
that means it
really is possible?
- Woo, so start there first.
If you have a mathematical
understanding of a theory
that is working, does
everything that comes
out of the math have to be true?
- I mean, we don't
obviously know the answer
to that question but it
does seem like nature
always finds a way.
I mean we've been sitting here
- I've seen Jurassic Park.
- talking about
black holes, yeah.
(all laughing)
- Right.
So black holes were originally
just a thought experiment
on paper and you know Einstein
thought nature would protect
us from their formation,
he didn't actually
think they were real.
He thought the math was
accurate and beautiful
and interesting and important
but not that it
could possibly form.
- He could have
predicted black holes
and just the idea
was so preposterous.
- He literally said well there's
much more important things
to think about right now,
and the fact that nature
figured out a way to make 'em
by killing off a few stars
is just kind of amazing
and it seems to happen
over and over again,
these seemingly
implausible concepts,
end up being challenged
by our limited intuition,
our limited intuition
is challenged by nature
actually doing it.
- The point is the
universe is big enough
with enough things happening
that even a completely
rare thing is gonna happen.
Or unlikely thing.
- Now I'm gonna
contradict myself
and say now that I'm
playing devil's advocate
I would say, you know,
the square root of two,
you asked about the
square root of nine,
the square root of two I
would say doesn't exist
in physical reality
as far as we know.
It's only in our
minds that it exists.
- Right, it's not a thing.
- I can't make anything that
has length square root of two
because it will eventually
end at some finite digit
which is an approximation
of square root of two
but it's not square root of two.
- The decimals go
on forever, like pi.
- Yes in irrational numbers
the decimals go on forever,
but any length of any thing
or any measurement of any kind
will only be a rational number
and an approximate to
an irrational, maybe.
So we can't measure pi, ever.
And we can't measure anything
with square root of two length.
- Bummin' me out.
- And so, then
- I want a pie with
the diameter pi
so it just goes on forever.
You'd always be baking it.
- So you can say well
that maybe I just gave you
an example that proves that
not every mathematical concept
can be realized in
physical reality.
- Okay but I'll give
you a pass that one.
What do you call it, in
golf what's it called?
Give you uh, a...?
- Oh God, you're asking
me sports questions.
(Neil laughs)
I remember in high school
I was into the coach.
- Thank God you looked at him.
- [Neil] Mulligan, I'll
give you a Mulligan,
I think it is.
- There you go.
- So alright, so now tell
us about negative mass.
- So negative mass
is problematic.
- Does it exist in anybody's --
- Not that we know of,
we have seen negative energies
in very subtle contexts
where you have two plates
that are very close
to each other where
you can create
a negative energy in the quantum
states between the plates.
- So these are, this is when--
- I dated some girls
with negative energy.
(all laughing)
- So you're talking about
like a capacitor plate,
like metal plates, you get
'em really, really close,
so that they're
closer to each other
than the wavelength of the
particles in the matter
that comprise them.
- Yeah in some sense,
it's like saying
if I can't have a water
wave between two walls
whose wavelength is longer
than the width
- Than the walls.
- between the walls, exactly.
I mean, not a standing wave.
And so the idea is that
it prunes some energy,
meaning that in some
sense there's less states
on the inside because of this
than there are on the
outside where you have
a whole continuum
of possibilities.
- So that's negative
energy between two plates.
- It can create under
certain circumstances
a negative energy, and
then you'll see a pressure
on the plates.
- Alright, so--
- The plates'll either push
apart or move together.
- If matter and
energy are equivalent,
E equals MC squared,
if you're gonna give
me negative energy,
why can't you hand
me negative mass?
- Yeah I mean, it--
- There.
(all laughing)
- Well here's, okay,
so here's the problem
with the negative mass
is that it seems
highly unstable.
So if I literally had a
particle like the electron
whose fundamental mass
was literally negative
and whose E equals MC squared
energy was literally negative
in that sense,
then it would be possible
to make tons of these
and balance it with the
generation of positive energy,
respect conservation
of energy, right?
So then I could get an
infinite energy resource
by making negative
energy particles
because that would have
to, by energy conservation,
lead to the creation of a
positive energy somewhere.
So runaway argument would be--
- And then when you
bring them together
they annihilate,
and then you have--
- Well I don't know, maybe
they're not antiparticles,
maybe they don't annihilate.
They just might
have negative mass.
So in other words, I
could have zero energy
in my laboratory
and I could have the best
energy company conceivable.
- Starting with zero energy.
- Zero energy, it costs me
nothing to make negative
energy particles because
I just have to create,
whether I like it to not,
positive energy in response,
meaning I can generate
incredible positive energy
at essentially no cost.
And that is just not,
it would be so unstable.
- [Neil] It's not
stable in the universe.
- It sounds good at first,
like we power New York City
at no cost.
We get rid of fracking and coal
and all of these you
know, fossil fuels,
but we also destroy the universe
in a completely unstable event
where the negative energy
runs out of control,
creating infinite
positive energy
and the whole thing blows up.
- Harrison, I think it was--
- That sounded like the
plot of a super villain.
(all laughing)
I think I've seen this
in a Spider-Man film.
- You're going to after
this episode airs, I'm sure.
- I think it's Kurt Vonnegut
that one of his books,
I don't remember which book
said the last
sentence ever spoken
in the universe was by
a scientist (laughing)
who says to the other scientist,
"Let's try it this other way."
(all laughing)
This is the scenario
you just described.
- Yeah, exactly.
- The whole universe goes
unstable and disappears.
- So some people say,
look, I have an observation
that proves that there's
not negative mass particles,
and that's the fact that the
universe appears to be stable.
- [Neil] And we're here.
- For, you know, for
14 billion years.
- [Neil] Wow.
- Pretty good.
- Alright, gimme another one.
- [Harrison] Alright,
we got Mike Berry--
- This stuff is
out there, squared.
- [Janna] I'm lovin' it,
this is right up my alley.
- Man.
- I was worried you were
gonna ask me about stuff
that happened more recently
than like half a billion
years ago, in which
case I'd be lost.
- Oh yeah, no, no, then
I'd take care of that one,
I'm good with that.
Alright.
- We have Mike Berry on Facebook
and he said, "I've never
heard this explained.
"If the observable universe
is roughly fifteen billion
"years old," as
you've just said,
"and if a star like
ours lasts 12 billon,
"how can our sun be a
third generation star?"
- Oh!
- So I would say 14 billion
is a little bit closer,
a little bit less
than 14 billion.
Because what's a
billion among friends?
- Between friends,
between astronomers.
- Yeah among astronomers.
- Yeah, we're around a
third generation star,
so the life expectancy
is not relevant
to what generation you are,
so there, because the
generation that we speak of
is we think of the stars
that create the elements
that are then scattered
back into the universe
and give another
generation this enrichment.
Those stars live, hundred
thousand, a million years.
- They're much shorter lived,
- Much shorter lived
- Because they didn't have
the heavy elements,
precisely because they
were first generation.
- Yeah, so you get
the high mass stars,
don't live very long,
and fortunately they blow up.
(Janna mumbles)
If they didn't blow up, they'd
keep their heavy elements
and the carbon,
nitrogen, oxygen, silicon
that's in our bodies, would
be forever locked in stars
and the universe would
have never had life,
would not have even had planets.
- Mm-hmm.
- Because these high mass
stars make these elements
and explode, scattering their
enrichment across the galaxy
it enables the next
generation of stars
to have slightly more of this,
the next generation of
stars have even more,
so that you'd expect
the frequency of planets
and other interesting chemistry
to take place will all the
elements on the periodic table,
the later your generation is,
the more chemical
latitude you have.
(Janna laughs)
- This is also the story
of the Greenbaum family.
- Oh is that right?
- The previous generation
living shortly, exploding.
- Oh, I get it.
And you are particularly
enriched. (laughs)
- A lot of chemical latitude.
- We've got time for one
more before we take a break.
- Sure, we got Jezebel
Lorelei from Facebook
and she writes,
- What, that's a real name?
Jezebel Lorelei?
- [Harrison] Yeah.
- Whoa that's a movie
name right there.
- [Janna] Yeah.
- What's the smallest
a black hole can be
and is there a name for the
atom that is one neutron less
than that atomic weight?
- Wait, say the last part again?
Is there an atom on
the periodic table
that's one neutron less
than that atomic weight?
Was that the question?
- So it's, what's the
smallest a black hole can be
and then is there
a name for an atom
that is one neutron
less than that weight?
- It's definitely less
than a neutron's weight.
Wait, so no wait,
actually it's not, no.
- Are those two
different questions?
- There's a comma in it.
- There's a comma?
- They've been jammed together.
- Don't you know the trick
of answering the question
you can and want to?
- Yeah, yeah, sure.
- Regardless of which
one you've been asked?
- Yeah okay,
she's just gonna answer the
one she knows she can answer.
Okay, go.
- So I can't remember
- Just the smallest black hole
just the smallest black hole.
- The actual number.
So we do know that
it is conceivable,
well we don't, okay.
It is conceivable that
a microscopic black hole
could be made under very
extraordinary conditions.
Now, we say that the
limit of the mass of it
is related to the
strength of gravity
and that gives us a scale
of how heavy it could be
and it's heavy compared
to things like electrons
but it's incredibly
light compared to
- [Neil] Golf balls
- Anything, right,
else on the, exactly.
So I think it's about the
weight of a little pile of sand.
Imagine a modest pile of sand.
That would be about the
weight it could maintain
and be consistent with
what we think is the limit
of the strength of gravity
and it would be an incredibly
tiny, microscopic black hole.
I mean, I can't even.
- Oh yeah, it'd be
really small, yeah.
The event horizon
size of the black hole
- It would be really small.
- But wait a minute.
- I should know the number,
10 to the, what is it,
10 to the minus 45
seconds after the big bang
was around the time
of quantum gravity
so if I multiplied that
maybe by the speed of light
I would roughly get the
size of a black hole
or something like
that, but anyway
you can ask me, ask me later,
I'll crunch some numbers.
- Okay, ten to the minus
fifteen meters or something.
- Yeah.
- So but, black holes evaporate
so they can become so small
that they don't exist at all.
- Oh, good point.
So those black holes
are incredibly unstable
to evaporation.
Because the idea that
Hawking foisted on its head,
- [Neil] The late
Stephen Hawking.
- The late Stephen Hawking,
the amazing Stephen Hawking,
that black holes, although
they let nothing out,
they somehow still evaporate.
That tremendous paradox that
we've been grappling with
since the 70s.
He also realized that
the temperature is colder
the bigger the black hole.
So they evaporate more
slowly, the bigger they are.
So we've never seen
astrophysical black
hole evaporate
'cause they're way too cold
for us to perceive
the evaporation.
- [Neil] That's
the big ones, yeah.
- The big ones that are
made by dying stars.
A microscopic one made
in the early universe
would presumably
evaporate in an instant.
And it would be, so people
have looked for that,
they've looked for
little explosions,
higher energy explosions
in the very early universe,
to see
- Gamma ray bursts.
- if there were
primordial black holes.
- Small bursts, but we
haven't found them though.
Yeah yeah yeah.
Oh right, yeah we gotta
wrap up this segment
of Cosmic Queries
The Out There Edition
We'll be right back.
(futuristic music)
- StarTalk, Cosmic Queries,
The Out There Edition.
This is the first time we've
done an Out There edition,
I think we have to
do this more often.
- This is fun.
- And Janna you are like
a neighbor up the street
at Barnard in Columbia,
so we'll just.
- Yeah absolutely, I
just take a stroll.
- [Neil] Yeah yeah we'll have
to like have a bat signal.
- Just stroll down the park.
(all laughing)
- Are you out there?
We need you here
for an Out There.
And Harrison again thanks
for bein' on StarTalk.
My Pleasure.
- So you got cosmic queries
for us, what do you have?
- Oh yeah, we got--
- Let's make this entire
segment the lightning round.
- Absolutely.
- Oh we're gonna be faster.
- They used to give me a bell,
I don't know what
happened to my bell.
But a lightning round,
so this will just be
more sound bite answers,
just so you can get
to more questions.
- Totally.
- Absolutely.
We have Tony_LE738 on Instagram,
Says, is there an
opposite to a black hole
that just spews out things?
- White hole.
(Neil and Janna laugh)
- Been there, done that.
- I think it just spews
out endless garbage.
No, okay.
Ben Ratner at Ben
Makes TV on Twitter,
what is your favorite
recipe for a good soup?
- Ooh, it would be,
primordial soup.
- Nice. (laughing)
- I didn't mean to step
on your announcement,
I was reading it out loud.
- Oh yeah for me a
good soup would be
all the basic ingredients
that are foundational
to biochemistry.
Carbon, nitrogen, oxygen.
Carbon is the stickiest
element on the entire table.
It can make more
kinds of molecules
than any other elements combined
so gimme a soup with carbon,
nitrogen and oxygen in it
and I can show you life.
- Can you read the ingredients
of the primordial soup,
does yours have the
- [Neil] The ingredients?
I used to be able to, let's see.
- Is this a real one?
- Oh yeah, okay.
Quick and easy instructions.
Mix soup, one can
of sea water, okay?
Lightning, heat, uncovered
in early years. (laughing)
This is like the
early earth year.
For two to three millennia.
Save the simple molecules
to form larger more
complex molecules.
For creamier soup, use
one can of organisms.
(all laughing)
So that'd be the best
kind of soup at all.
- I prefer a split pea.
- [Neil] Alright
keep goin' Harrison.
- Alright we got Joshua
Willham from Facebook.
- [Neil] We're
still in quick mode.
Lightning mode.
- Yeah, if you could
suddenly know the answer
to any question, what
question would you choose?
- Suddenly knowing the
answer is so disappointing.
As a scientist the whole
fun is figuring it out.
I didn't know if I'd suddenly
wanna know the answer
to any question other
than when's my Uber coming
or something.
(all laughing)
- You just have to
look at your phone.
- Yeah that's not a
mystery on that one.
- They have physics
that are unbelievable
where the car just
jumps through a building
and you're like that was
some physic impossibility.
- Or it just does a flip
around and you know.
- Did Uber discover a
black hole in the city,
I dunno how it jumped.
- Worm hole, worm hole
through the building.
Still, for me the answer
I want is to the question
we don't know yet to ask.
- [Harrison] Ooh.
- Would you recognize
it if you heard it?
- Because the day we learn
what that question is
I no longer care.
I'll await the day when
the next question comes
that I didn't know to ask.
And this is strongly
resonant with Janna's answer,
where the quest to the answer,
science is not so
much about answers
but the search for answers
and that's where you learn,
you stumble on things,
you discover the
structures of things
you didn't even know
that was a question
you needed to ask.
So yeah I'm all into the search.
So these are--
- I'd like to have the
answer, just not suddenly.
- [Neil] But not
sudden. (laughs)
- I don't want it
to be never either.
Never is frustrating.
- Very good, that's a
very healthy posture.
Otherwise there's
a psychological
problem you're having.
- Yeah there is, yeah exactly.
- I like an escape room
so within 60 minutes,
that's when I wanna
get the answers.
Alright we got Scott
York on Instagram.
Could dark matter or dark energy
be any indication
of alien technology
that is beyond
human comprehension?
- Ooh. Go.
Don't look at me!
- This feels more like a Neil.
- Okay here's what I would say,
I'll give you my answer
but I wanna hear
your answer, okay?
Just because there's
something in the universe
we don't understand, doesn't
mean it's aliens. (laughing)
It doesn't mean it's magic.
- Otherwise my VCR
was made by aliens.
(All laughing)
- Right, you still have a VCR?
- Exactly, the fact
that I have a VCR--
- We really need to get
you that grant, my God.
- Would reflect alien
intervention somehow.
- First you talk about
Mary Tyler Moore,
you're talkin' about VCRs,
how the hell old are you guys?
No.
- Oh sorry, my beeper went off.
(all laughing)
- Oh, the beeper.
So I think, wait what
was the question again?
- [Janna] Could dark
matter and dark energy
be evidence of aliens?
- It's tempting,
it's always tempting
to ascribe something
completely extraordinary
as the cause for something
we don't understand.
We've been doin' that forever.
But as a scientist you
have to resist that
because the history
of that exercise
is one of abject
failure persistently.
So to say it was actually magic,
or it's actually God, or
it's actually an alien,
and then you study
it and it's reducible
to known forces, or maybe
you'll discover a new force
but it's still not magic,
it's still not God,
and it's still not aliens.
So if I'm betting I would
say it's probably not as much
as we would really
love it to be.
- Now the place we should
be lookin' for aliens
is a place we actually
know where to look
which is on exoplanets
and that's where there really
is a very serious prospect
that there are aliens.
Now, having said that--
- [Neil] These are planets
orbiting other stars.
- Yes, exactly, planets
orbiting other stars.
We think that in our Milky Way
of which there are hundreds
of billions of stars
that there are
probably more planets
than there are stars
in the Milky Way
and so that's suddenly
a stunning number
that we didn't realize,
what, 20 years ago.
- Yeah but you're
just talking about
some kind of living organism.
- Right, I was gonna say,
don't be disappointed.
- We're talking about aliens,
we're talkin' about
- yeah, we can talk to 'em
- Serious ray gun
aliens, ya know?
- Absolutely.
- The aliens, right.
- Area 51.
- I know.
They're probably
- Abducted
- More like the kind of
thing you wipe off your shoe,
which is sad.
- Yeah, exactly.
- That's for sure.
- Some primordial ooze that
is itself the mat of life.
You're so un-fun with that.
It's true but un-fun.
- Who knows?
- A book that says
How to Serve Man
but turns out it's a cookbook.
Alright, K Fudge from
Instagram, how many black holes
are there?
- Kate Fudge?
- K Fudge.
- K Fudge.
- [Neil] Oh excuse me I
thought you said Kate Fudge.
- Somebody's hungry.
- [Neil] Alright.
- How many black
holes are there?
- So in our galaxy,
we just said that there
are a few hundred billion
stars in our galaxy.
About 1% of them at
the end of their lives
are going to be big
enough to collapse
all the way through
to become black holes.
And so that's a lot, right?
- Yeah 1% of a hundred billion
is a billion black holes.
- It's a billion black holes,
and in addition to that we know
there are tens of thousands
of black holes around the
super massive black hole
at the center of our galaxy.
So the center of our
galaxy harbors a black hole
a few million times
the mass of the sun
and it has tens of
thousands of black holes
specially segregated around it.
So that's just our galaxy.
Now you're saying in
the observable universe
there are as many galaxies
as there are stars
in the Milky Way.
You got a lot of
black holes out there.
- And all evidence shows
that every red blooded galaxy
like the Milky Way has got
a super massive black hole
in its center.
- Yeah so we've got hundreds
of billions of those
and hundreds of
billions times a billion
of the smaller ones.
- Surrender now.
(all laughing)
- Is that like the
worst Milky Way?
Like a Milky Way candy
bar that's realistic
has a black hole in
the middle of it?
No thank you.
On the black hole tangent, Tony,
I'm sorry, Jeek.2 at Instagram,
wrote "can a black hole
eat another black hole?"
And if so,
- Oh yeah.
- Would it lead to its growth?
- Absolutely.
- Like a Pac Man
theory of black holes.
- Absolutely, one of the most--
- Pac Man, your references
are so classic old!
I love it
- Pac man!
- But I have to make
fun of it 'cause we had
- Can we come to your house
and see what you've got
the set up there?
- I've been to a couple of
80's escape rooms recently
so it's on my mind.
- Do you have a cell phone?
(all laughing)
- It's very large.
- Wait, what was the question?
Oh yeah, black holes
eating other black holes.
That is one of the most
exciting things that's happened
this century, is
the direct recording
of the sound of
space-time ringing
due to the collision
of two black holes,
which if you want to call
it them eating each other
you could.
They merged and they
created a bigger black hole
so each one was about 30
times the mass of the sun
and so we know that there
is a black hole out there
in that rough direction,
as far as we can ascertain,
that is 60 times
the mass of the sun,
and yes they get
bigger, they get bigger
by almost as much
as you would think.
The energy that they lost
in terms of like, literally,
E equals MC squared energy
that wasn't the sum of the parts
came out in this
ringing of space-time.
And it was recorded by LIGO,
this fantastic instrument.
It happened in,
must've been 2015.
- It's a new window
to the universe
that's measuring the ripples
in the fabric of space
rather than the ripples
in the energy of light.
- And this is what Black
Hole Blues was all about,
I was writing it while they
were on this campaign, yeah.
- Your book.
- And they hadn't succeeded
while I was writing
and I was really writing
it, precisely ties in
with what we were
talking about earlier
about the pursuit.
And you know it
was 50 long years
that they strove to
build this instrument
and get this detection
- So wait a minute
your title of your book
is Black Hole Blues
is that 'cause you didn't
think they would find it?
- Yeah.
- And then they found it
and now your book
has the wrong title.
- Yeah, so amazingly, Rai
Weiss, who won the Nobel Prize
alongside Kip Thorne
and Barry Barish
for that discovery, said to me
about a month before
the detection occurred,
"If we don't detect black
holes, this thing is a failure."
And so I got the title,
really thinking about
Rai saying that.
That he's now in his 80s, he
started this as a young man,
and it was the Black Hole Blues,
but they told me well
before the book came out,
they told me about
the detection,
so I didn't wanna re-write it,
'cause I think it is
all about the pursuit,
but I did have a lovely close
where they make the discovery.
- Okay, I didn't get to
that close yet in your book.
- [Janna] Yeah (laughing)
- Now I'm gonna go
ahead to find it.
Gimme more.
- Alright, we got Michelle
Akempura from Facebook,
"if everything is supposed
to be expanding away from
each other how come our galaxy
is on a collision
course with Andromeda?"
- Okay, I got this.
I got this.
- I'm gonna have to
throw down after.
- I got this.
So the expansion
of the universe,
is think of it as
a stretchy fabric
that if, and it doesn't
matter where you are,
you'll think you're at the
center of that stretching
and you'll see objects
moving away from you
in every direction.
Objects that are near you will
not be moving away as fast
as objects that
are farther away.
'Cause every, let's say for
every meter it stretches
ten centimeters, okay?
Well that means at two meters
it stretches 20 centimeters.
At three meters
it's 30 centimeters.
That's how stretching
works in the fabric.
So, all galaxies have speeds
relative to each other.
If you have a nearby
galaxy it's goin' faster
than the stretching
speed of the universe
in the space near me,
so my gravity overcomes
anything the universe is doing
for things nearby.
So nearby galaxies are
goin' on like the universe
is not expanding, they
don't really care.
Their gravity is strong
enough to create motions
that overcome the expansion
of the universe itself.
But we're not gonna collide
with a distant galaxy
'cause the stretching
of the universe
is taking us away faster
than that can ever happen.
- I just wanted to
make reference to,
I think it's Annie
Hall, the line where
- [Neil] Oh okay go on.
- The character
won't do his homework
because he's,
- The kid, the kid
- because the
universe is expanding,
and his mother says
"you live in Brooklyn,
Brooklyn is not expanding!"
(all laughing)
And it's true, Brooklyn
is not expanding
for precisely the
reasons Neil just gave
that the earth is bound together
more strongly than the
expansion can tear apart.
- [Neil] Universe
in this section,
the expanding universe is not
gonna break apart the earth.
- Yeah.
- But now a bunch of
developers have bought Brooklyn
and it is expanding
at an incredible pace.
(Janna laughs)
Alright so we got,
- It's gotta be fast!
- Kyle Toth from
Venice, Florida.
"What lies beyond the
observable universe?
"Do we have an estimated
size of the entire universe?"
- Ooh.
- I love this.
- Janna take it.
And by the way, but we're
still kind of in speed mode
but we're gonna end with
your answer to this question.
- Okay, lovely.
- No pressure.
- That's a lot of pressure.
It is conceivable that the
universe is actually finite
in the same sense that
the earth is finite.
If I leave New York City and
I walk in as straight a line
as possible, and I go for
as long as I possibly can,
I come back to New
York city again.
It is conceivable
- Without ever
falling off an end.
- Without ever
turning left or right,
falling off an edge, going
forward and backward.
- So you can walk
forward forever.
- Forward forever, it
just keeps coming back
around and around
- In a finite space
- and around again.
Now if the whole
universe is like this
I literally would leave the
Milky Way in a spacecraft,
I would travel in
a straight line,
watch the galaxy
recede behind me,
not turn left, not turn
right, never stop, forward,
not fall off the
edge of the universe,
but see the Milky Way
approach in front of me again.
- What?
(all laughing)
How many, how many--
- We need a mic drop
on this, alright here.
(imitating banging)
- There you go.
(all laughing)
- Did you hear it?
- That was an audio
mic drop right there.
- How many seasons
of this podcast
would you have to
listen to before you saw
the Milky Way again?
- That's right,
we would look back
and because light has
a finite travel time
we would hear podcasts
from our past,
like you could look
back and see yourself
as a child if you
waited long enough
for the light to come
back around again.
- From the other
direction, yeah.
- From the other direction,
and so we could actually
resolve serious quandaries
by being like, well if
we wait a billion years
we can actually watch
it again. (laughs)
- Just to get to
the arguments made
about who said
what over dinner.
- To see what really happened.
Exactly.
- Exactly.
- Who broke the plate, right?
- There's a sad
old astronaut alone
like, "I told you, Janice.
This was all worth it."
- So but okay so that's
a finite universe
but just as equally the
universe could be infinite
and we're just our
own observable pocket
within some infinite universe.
- Right it is also possible,
that the universe is infinite
and beyond the
observable universe
is this infinite
stretch of space.
But you know, Einstein said
"only two things are infinite,
"the universe and
human stupidity."
And then he said, "I'm not
so sure about the universe."
(all laughing)
- That sounds like we should
end on that note doesn't it?
- Einstein mic drop.
- Wow, that was Cosmic
Queries, Out There Edition,
our very first on that theme.
But clearly we're gonna
have to do this again.
'Cause there's no end to
those kind of questions,
particularly if we get Janna
kinda answers right there.
Janna it was great, and
I've been loving your book,
- Thanks it was fun.
- [Neil] The Black
Hole Blues. (laughing)
Harrison thanks for
coming back on StarTalk.
- Oh my pleasure.
- [Neil] And
HarrisonGreenbaum.com,
look for where you,
for your stand up gigs,
and you're also a magician.
- Absolutely.
- [Neil] Like as you said,
that's the double
threat. (laughing)
- Very common.
- Very common, very common.
And I've been your host,
Neil deGrasse Tyson.
This has been StarTalk.
And as always, I bid
you to keep looking up.
(futuristic music)
