May 22, 2018 • 9 mins
Days before his death, theoretical physicist Stephen Hawking finished what would be his final research paper. Learn about his last take on the multiverse in this episode of BrainStuff.
Learn more about your ad-choices at https://www.iheartpodcastnetwork.com
See omnystudio.com/listener for privacy information.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff,
Lauren voc obam here. Days before his death. On March fourteen, eighteen,
famed theoretical physicist and cosmologist Stephen Hawking completed what would
be his final research paper. It has since passed peer
review and was published online in the Journal of High
Energy Physics on April. Written with co author Thomas Hertog,
(00:26):
a theoretical physicist at the University of louisn Belgium, the
paper adds another facet to our understanding of this universe
that we live in, and needless to say, it's complicated.
Titled a Smooth Exit from Eternal Inflation, the publication discusses
an enigmatic problem facing cosmologists. But before we delve into
(00:47):
the crux of the study, let's go back to when
our universe was a baby, some thirteen point eight billion
years ago. A lot of evidence suggests that our universe
originated from a singularity, an infinitely dense point from which
all the universe as we know it was born. We
call that event the Big Bang. But how the singularity
came to be and why the Big Bang happened isn't
(01:09):
of concern right now. We're interested in what happened immediately
after our universe was spawned, a period known as inflation.
Cosmologists predict that inflation occurred over a vanishingly small period
right after the Big Bang, during our universe's very first
ten to thirty two seconds. During inflation, the universe expanded
exponentially and much faster than the speed of light. After
(01:32):
only a second, the energy from this inconceivably gargantuan explosion
condensed to form sub atomic particles that, over millions of years,
created the stars, galaxies, planets, and, after another few billion years,
a life as we know it. Once this inflationary period ended,
the universe's rate of expansion slowed, but it continues to
(01:53):
expand to this day. Because inflation powered a faster than
light speed expansion, The observable uni verse that we see
today is not the entire universe. Rather, we exist inside
a region of the cosmos that light has had time
to reach. It's like dropping a pebble into a calm
swimming pool. The first circular ripple to propagate from the
(02:14):
splash travels at a fixed speed across the surface of
the pool. If we imagine that the limit of our
observable universe is that ripple traveling across the pool at
the speed of light. It's not that nothing exists beyond
that ripple. There's more pool or universe beyond it. We
just can't see it yet. So the consequence of inflation
(02:34):
is that there should be a lot more universe beyond
what we can see, even with our most powerful telescopes,
and cosmologists have been grappling with the possibility that our
universe is not the only universe. In fact, we could
be nothing more than a single bubble in an infinite
froth the ocean, a concept known as the multiverse. The
idea here is that inflation didn't happen once, It's always
(02:58):
happening via some infinitely vast chain reaction known as eternal inflation.
One universe will appear, and inflation will take over, expanding
that universe, and that universe will have its own quantum
instabilities that will spawn more singularities that go on to
create more universes. It's like blowing up a party balloon
that itself spawns many other party balloons that are rupped
(03:20):
from its rubbery surface seemingly at random. If this situation
sounds chaotic, it is. Proponents of this hypothesis think that
eternal inflation is unstoppable, vastly complex, and continually generating new universes,
and the math of this situation suggests that the multiverse
acts like a fractal, fractals being sets of data that
(03:42):
contain repeating patterns at every scale. Visually, this means that
complex shapes look pretty much the same at a wide
range of scales, like a small piece of it looks
pretty similar to the whole structure. Think of a head
of cauliflower. Any given segment will resemble the whole head,
and if you zoom in further, each clus store of
buds resembles the larger segments. It's worth noting that in
(04:04):
this theory, each successive universe and the multiverse doesn't likely
share the same physics as our universe. One universe might
not have gravity, another may not support the forces that
hold matter together. There would be a lot of stillborn
universes that just don't amount too much. We humans are
simply lucky to have a universe that has the right
environment to create what we see. A philosophical argument known
(04:27):
as the anthropic principle. The problem with eternal inflation is
that it's messy and infinite, and that the hypothesis is
ultimately untestable. So what does Hawking and her tog's research
have to do with this unrelenting multiverse In the multiverse.
Our universe is merely a pocket universe where inflation has ended,
(04:49):
and despite the odds, it found enough calm to create
a bounty of stars and galaxies and a bunch of
humans living on some random rock pondering the cosmos. What's
going on beyond our pocket of calm is, however, somewhat different,
Hawking said in an interview in Tween. The usual theory
of eternal inflation predicts that globally, our universe is like
(05:10):
an infinite fractal with a mosaic of different pocket universes
separated by an inflating ocean. The local laws of physics
and chemistry can differ from one pocket universe to another,
which together would form a multiverse. But I have never
been a fan of the multiverse. If the scale of
different universes in the multiverse is large or infinite, then
the theory can't be tested. The problem, according to Hawking
(05:34):
in Her Dog, allies with the incompatibility of Einstein's general
relativity that governs the evolution of the universe and quantum
mechanics that seeds the creation of new universes through quantum fluctuations.
The eternal inflation model of the multiverse, as her Dog
said in a press release quote, wipes out separation between
classical and quantum physics. As a consequence, Einstein's theory breaks
(05:57):
down in eternal inflation. Their study doesn't go as far
as reconciling general relativity with quantum physics, a quest that
has so far been unsuccessful, but they use the math
of string theory to help simplify the multiverse model. A
quick recap. String theory predicts that all subtomic particles in
our universe are in fact composed of one dimensional strings
(06:19):
that propagate through space. The vibrational state of these strings
is what gives these particles their quantum state such as charge, spin,
and mass. But string theory also predicts the existence of
the hypothetical graviton, a quantum particle that carries the force
of gravity. The math that suggests that gravitons exist is solid,
but no one's been able to point to one yet.
(06:41):
String theory would therefore provide an explanation of how Einstein's
general relativity gravity jibes with quantum physics using the mathematical
framework of string theory. This final study from Hawking simplifies
the multiverse. Hawking and her dog used the string theory
concept of holography, who reduce our three dimensional universe down
(07:02):
to a two dimensional surface from which the universe we
know and love is projected. By doing this, they were
able to describe eternal inflation without general relativity, creating a
timeless state. Her dog explained this move in a statement.
When we trace the evolution of our universe backwards in time,
at some point we arrive at the threshold of eternal inflation,
(07:24):
where our familiar notion of time ceases to have any meaning.
The math is complex, but the result is interesting. The
calculations have the effect of turning the infinite and fractal
multiverse into a far simpler and finite situation that eternal
inflation does predict. Hawking said this about it. We are
(07:44):
not down to a single unique universe, but our findings
imply a significant reduction of the multiverse to a much
smaller range of possible universes. To put it in perspective,
Hawking's final paper doesn't revolutionize our understanding of how the
universe and indeed the multiverse works, but it is a
valuable addition to a huge field of theoretical work. Specifically,
(08:07):
her TG hopes that this study may help us search
for ancient gravitational waves that were generated by eternal inflation.
These ripples in space time are far too weak for
current gravitational wave detectors to detect. However, we need to
wait until advanced space based observatories such as the European
Space Agencies planned LIESA mission are launched. Regardless of whether
(08:30):
the study leads to groundbreaking discoveries about the cosmos that
we live in, it's a testament to a great scientist
who worked tirelessly his entire life to answer some of
the biggest questions that humanity has pondered, and on Hawking's shoulders,
other great minds will build on this work to hopefully
decipher whether our universe is unique or if it's just
one bubble chaotically floating in the ocean of the multiverse.
(08:57):
Today's episode was written by Ian O'Neill and produced by
Tyler Clang with kind engineering assistance from Ramsay Yount. For
more on this and lots of other eternally expanding topics.
Visit our home planet, how staff Works dot com
Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff,
Lauren voc obam here. Days before his death. On March fourteen, eighteen,
famed theoretical physicist and cosmologist Stephen Hawking completed what would
be his final research paper. It has since passed peer
review and was published online in the Journal of High
Energy Physics on April. Written with co author Thomas Hertog,
(00:26):
a theoretical physicist at the University of louisn Belgium, the
paper adds another facet to our understanding of this universe
that we live in, and needless to say, it's complicated.
Titled a Smooth Exit from Eternal Inflation, the publication discusses
an enigmatic problem facing cosmologists. But before we delve into
(00:47):
the crux of the study, let's go back to when
our universe was a baby, some thirteen point eight billion
years ago. A lot of evidence suggests that our universe
originated from a singularity, an infinitely dense point from which
all the universe as we know it was born. We
call that event the Big Bang. But how the singularity
came to be and why the Big Bang happened isn't
(01:09):
of concern right now. We're interested in what happened immediately
after our universe was spawned, a period known as inflation.
Cosmologists predict that inflation occurred over a vanishingly small period
right after the Big Bang, during our universe's very first
ten to thirty two seconds. During inflation, the universe expanded
exponentially and much faster than the speed of light. After
(01:32):
only a second, the energy from this inconceivably gargantuan explosion
condensed to form sub atomic particles that, over millions of years,
created the stars, galaxies, planets, and, after another few billion years,
a life as we know it. Once this inflationary period ended,
the universe's rate of expansion slowed, but it continues to
(01:53):
expand to this day. Because inflation powered a faster than
light speed expansion, The observable uni verse that we see
today is not the entire universe. Rather, we exist inside
a region of the cosmos that light has had time
to reach. It's like dropping a pebble into a calm
swimming pool. The first circular ripple to propagate from the
(02:14):
splash travels at a fixed speed across the surface of
the pool. If we imagine that the limit of our
observable universe is that ripple traveling across the pool at
the speed of light. It's not that nothing exists beyond
that ripple. There's more pool or universe beyond it. We
just can't see it yet. So the consequence of inflation
(02:34):
is that there should be a lot more universe beyond
what we can see, even with our most powerful telescopes,
and cosmologists have been grappling with the possibility that our
universe is not the only universe. In fact, we could
be nothing more than a single bubble in an infinite
froth the ocean, a concept known as the multiverse. The
idea here is that inflation didn't happen once, It's always
(02:58):
happening via some infinitely vast chain reaction known as eternal inflation.
One universe will appear, and inflation will take over, expanding
that universe, and that universe will have its own quantum
instabilities that will spawn more singularities that go on to
create more universes. It's like blowing up a party balloon
that itself spawns many other party balloons that are rupped
(03:20):
from its rubbery surface seemingly at random. If this situation
sounds chaotic, it is. Proponents of this hypothesis think that
eternal inflation is unstoppable, vastly complex, and continually generating new universes,
and the math of this situation suggests that the multiverse
acts like a fractal, fractals being sets of data that
(03:42):
contain repeating patterns at every scale. Visually, this means that
complex shapes look pretty much the same at a wide
range of scales, like a small piece of it looks
pretty similar to the whole structure. Think of a head
of cauliflower. Any given segment will resemble the whole head,
and if you zoom in further, each clus store of
buds resembles the larger segments. It's worth noting that in
(04:04):
this theory, each successive universe and the multiverse doesn't likely
share the same physics as our universe. One universe might
not have gravity, another may not support the forces that
hold matter together. There would be a lot of stillborn
universes that just don't amount too much. We humans are
simply lucky to have a universe that has the right
environment to create what we see. A philosophical argument known
(04:27):
as the anthropic principle. The problem with eternal inflation is
that it's messy and infinite, and that the hypothesis is
ultimately untestable. So what does Hawking and her tog's research
have to do with this unrelenting multiverse In the multiverse.
Our universe is merely a pocket universe where inflation has ended,
(04:49):
and despite the odds, it found enough calm to create
a bounty of stars and galaxies and a bunch of
humans living on some random rock pondering the cosmos. What's
going on beyond our pocket of calm is, however, somewhat different,
Hawking said in an interview in Tween. The usual theory
of eternal inflation predicts that globally, our universe is like
(05:10):
an infinite fractal with a mosaic of different pocket universes
separated by an inflating ocean. The local laws of physics
and chemistry can differ from one pocket universe to another,
which together would form a multiverse. But I have never
been a fan of the multiverse. If the scale of
different universes in the multiverse is large or infinite, then
the theory can't be tested. The problem, according to Hawking
(05:34):
in Her Dog, allies with the incompatibility of Einstein's general
relativity that governs the evolution of the universe and quantum
mechanics that seeds the creation of new universes through quantum fluctuations.
The eternal inflation model of the multiverse, as her Dog
said in a press release quote, wipes out separation between
classical and quantum physics. As a consequence, Einstein's theory breaks
(05:57):
down in eternal inflation. Their study doesn't go as far
as reconciling general relativity with quantum physics, a quest that
has so far been unsuccessful, but they use the math
of string theory to help simplify the multiverse model. A
quick recap. String theory predicts that all subtomic particles in
our universe are in fact composed of one dimensional strings
(06:19):
that propagate through space. The vibrational state of these strings
is what gives these particles their quantum state such as charge, spin,
and mass. But string theory also predicts the existence of
the hypothetical graviton, a quantum particle that carries the force
of gravity. The math that suggests that gravitons exist is solid,
but no one's been able to point to one yet.
(06:41):
String theory would therefore provide an explanation of how Einstein's
general relativity gravity jibes with quantum physics using the mathematical
framework of string theory. This final study from Hawking simplifies
the multiverse. Hawking and her dog used the string theory
concept of holography, who reduce our three dimensional universe down
(07:02):
to a two dimensional surface from which the universe we
know and love is projected. By doing this, they were
able to describe eternal inflation without general relativity, creating a
timeless state. Her dog explained this move in a statement.
When we trace the evolution of our universe backwards in time,
at some point we arrive at the threshold of eternal inflation,
(07:24):
where our familiar notion of time ceases to have any meaning.
The math is complex, but the result is interesting. The
calculations have the effect of turning the infinite and fractal
multiverse into a far simpler and finite situation that eternal
inflation does predict. Hawking said this about it. We are
(07:44):
not down to a single unique universe, but our findings
imply a significant reduction of the multiverse to a much
smaller range of possible universes. To put it in perspective,
Hawking's final paper doesn't revolutionize our understanding of how the
universe and indeed the multiverse works, but it is a
valuable addition to a huge field of theoretical work. Specifically,
(08:07):
her TG hopes that this study may help us search
for ancient gravitational waves that were generated by eternal inflation.
These ripples in space time are far too weak for
current gravitational wave detectors to detect. However, we need to
wait until advanced space based observatories such as the European
Space Agencies planned LIESA mission are launched. Regardless of whether
(08:30):
the study leads to groundbreaking discoveries about the cosmos that
we live in, it's a testament to a great scientist
who worked tirelessly his entire life to answer some of
the biggest questions that humanity has pondered, and on Hawking's shoulders,
other great minds will build on this work to hopefully
decipher whether our universe is unique or if it's just
one bubble chaotically floating in the ocean of the multiverse.
(08:57):
Today's episode was written by Ian O'Neill and produced by
Tyler Clang with kind engineering assistance from Ramsay Yount. For
more on this and lots of other eternally expanding topics.
Visit our home planet, how staff Works dot com
BrainStuff News
Hosts And Creators
Josh Clark
Jonathan Strickland
Ben Bowlin
Lauren Vogelbaum
Cristen Conger
Christian Sager
Popular Podcasts
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
24/7 News: The Latest
The latest news in 4 minutes updated every hour, every day.
Crime Junkie
Does hearing about a true crime case always leave you scouring the internet for the truth behind the story? Dive into your next mystery with Crime Junkie. Every Monday, join your host Ashley Flowers as she unravels all the details of infamous and underreported true crime cases with her best friend Brit Prawat. From cold cases to missing persons and heroes in our community who seek justice, Crime Junkie is your destination for theories and stories you won’t hear anywhere else. Whether you're a seasoned true crime enthusiast or new to the genre, you'll find yourself on the edge of your seat awaiting a new episode every Monday. If you can never get enough true crime... Congratulations, you’ve found your people. Follow to join a community of Crime Junkies! Crime Junkie is presented by audiochuck Media Company.