i think it's safe to say that einstein
was
a pretty smart guy his theory of general
relativity states that
matter and energy then the very fabric
of space-time and that revelation gave
us
such a useful description of how gravity
works that it's been the go-to for
astronomers for more than a century
still as good as it is general
relativity
isn't perfect and there are situations
where einstein's equations
break down like at the center of a black
hole or the singularity before the big
bang
however a new paper suggests the key to
filling in those gaps
may be discovered by searching for and
this is a highly technical term here
the quantum fuzziness of space-time
gravity is somewhat of the odd one out
when it comes to the four
fundamental forces of nature according
to einstein it works by curving
space-time
affecting how objects like planets and
apples
travel through it the other three forces
the electromagnetic force and the strong
and weak nuclear forces
can be described using the standard
model of particle physics
these three forces are carried by
subatomic particles
called bosons the strong force is
carried by the gluon
electromagnetism is carried by a boson
you've probably heard of
the photon and the weak force is carried
by the w
and z bosons we've seen these bosons
experimentally
but we've never observed a particle that
carries the force of gravity
and that's irksome because a
hypothetical boson called a graviton
could solve some major issues in physics
firstly it would fit neatly into the
pattern the other three forces have set
to have gravity off doing its own thing
and playing by its own rules it just
doesn't sit right at least not with a
lot of theorists
more importantly it could finally bridge
the divide between general relativity
and quantum mechanics right now general
relativity is great at describing how
gravity works at scales ranging from
sub millimeter to cosmological but it
doesn't work
at quantum levels a full theory of
quantum gravity could finally
expand einstein's ideas to fill in these
gaps in our understanding
but gravitons if they exist would be
difficult to detect
by their nature despite another force
literally being called
the weak force gravity is by far the
weakest
of the quartet the renowned physicist
freeman dyson
suggested that a hypothetical detector
sensitive enough to observe a single
graviton
would be so massive that the detector
itself would collapse
into a black hole but what if we're
going about this the wrong way
what if instead of trying to find just
one graviton
we search for a telltale sign that only
a group of them
can create that's what three researchers
proposed in a paper from october of 2020
the physicists were inspired by brownian
motion which describes how particles in
a fluid
bounce around randomly if gravity really
is carried by bosons
then maybe they move around randomly too
creating a sort of
noise or fuzziness that existing
gravitational wave detectors like ligo
can suss out of course the noise has to
be pronounced enough for ligo to notice
it's a bit beyond the scope of this
episode but just know that waves like
light can come in different quantum
states in fact
ligo uses light in a squeezed state
to enhance sensitivity the researchers
calculated that gravitational waves in
different quantum states would produce
different amounts of noise
waves in a coherent state are like
ripples in a pond they're produced
during black hole mergers
and ligo is tuned to search for them
unfortunately
in this state gravitons would hardly
make any noise
however according to the researcher's
calculations
gravitational waves in the so-called
squeezed state
should produce much more noise and that
noise
should increase exponentially the more
the gravitons are
squeezed so let's just start looking for
some squeezed gravitational waves right
uh yeah not so fast it's not
clear if they even exist the researchers
suggest that they could be squeezed into
existence during the late stages of
black hole mergers
or during an early period in the
universe if that's true
or if there's some other source of
squeezed gravitational waves out there
and if we can make instruments sensitive
enough to hear the noise of gravitons
then maybe we can finally find a way to
bring quantum mechanics
and general relativity together if you
want to know more about
gravitational wave detectors like ligo
check out my video on these
awesome machines here and make sure to
subscribe to seeker for more videos like
this one
thanks for watching and i'll see you
next time