The Big Bang.
A torrent of energy that propelled our Universe from nothing into everything, creating both space and time.
It's the best theory yet of what happened at the beginning of time.
But a new generation of scientists is daring to contemplate what was once thought impossible, are we wrong about the Big Bang? And might we soon discover what happened before the beginning?
How did the Universe begin?
We've all heard of the Big Bang, but how do we really know that's the way it was?
I mean, after all, nobody was around to see it happen.
And if that question seems hard to answer, try this one, what happened before the Universe began?
I first encountered this eternal question at the Methodist church.
♪ Sweet chariot ♪
♪ coming for to carry me home ♪
In the book of Genesis, God said, "let there be light, and there was light."
God then created the Heavens and the Earth.
But if everything began at this moment, how was God around to create it?
Could there ever have been a time before time?
It's a question that has intrigued scientists and philosophers and the rest of us for more than 5,000 years.
But in the 1920s, a scientific discovery shone some new light on the beginning of time and what might have come before, thanks to this man, Edwin Hubble.
Atop Mount Wilson in Southern California, Hubble aimed a powerful, new weapon at the heavens, the mighty Hooker 101-inch telescope.
As he looked through it, he became the first man to appreciate the true scale of the Universe.
Hubble saw that small patches of blurry sky were not gas clusters, but in fact other galaxies.
The Universe was filled with not thousands, but hundreds of billions of them.
Remarkable as this discovery was, Hubble's observations would lead to an even more profound conclusion, the Universe is expanding, every single galaxy drifting farther and farther apart.
Run this picture back in time, and all the math points to a single moment of an infinitely small, infinitely dense beginning to our Universe.
Scientists have a name for this initial state -- a singularity.
Before this Big Bang, there is nowhere and no-when. There is literally nothing before this beginning.
Run the clock forward from that singularity, and the starting gun is the Big Bang...
...A colossal explosion of energy and matter that gave birth to everything we see in the sky today.
It also created space and time.
As all the radiation and matter shoots out in different directions, the Universe eventually starts to cool.
Gravity causes matter to clump together, and stars are born... And then explode.
Later, swirling discs of dust and rocks gather around newer stars.
Eventually, several billion years after the Big Bang, we get a planet like Earth.
This mind-twisting story has become the new dogma, but however robust, the Big Bang is still just a theory.
Princeton Professor of physics Dr. David Spergel has spent much of his career trying to understand if and how this cataclysmic event happened.
People sometimes call him "Mr. Universe."
For Spergel, the Big Bang is still the most complete and scientifically sound model of the early Universe.
Everything around us came from the hot Big Bang.
The Universe started out --
Big Bang Theory, very, very hot, very dense.
That hot radiation cooled.
From that emerged matter, radiation, everything that makes up the world around us. And here we are at Bell Labs at Crawford Hill, the place where the hot Big Bang theory really all started, in some ways.
Arno Penzias and Robert Wilson are a pair of radio astronomers who worked here at Bell Laboratories. What they were doing is they were studying the microwave sky as Bell Labs was exploring the idea of using it for microwave communication.
It was 1964.
At this point, the two men were not trying to solve any big cosmic questions.
They were just trying to get the darn thing to work.
For starters, a mysterious hiss was interfering with their radio signal.
Penzias and Wilson were really good radio astronomers, so they built a really nice telescope. And they designed it so there shouldn't be any background, yet it was there.
This background hiss they heard was coming from every corner of the sky.
Wilson and Penzias tried everything, even sweeping the dirt and leaves out of the antenna, but still there was noise. They tried cooling the receivers with liquid helium. Still there was noise. They even removed a family of nesting pigeons and their associated droppings. And still the noise would not go away.
Sometimes science consists of cleaning up a lot of stuff and seeing what's left behind. Having eliminated anything they can think of, they realized there had to be something else there.
The only possibility was that it was coming from someplace outside our galaxy, and that seemed like such a far-out idea.
We just didn't know what to do with that result.
Consulting with a team of Princeton physicists, Wilson and Penzias realized that the only reason something could come from every part of the sky is if it were actually a faint echo of a huge cosmic event.
We had really measured the background temperature, the remnant noise from the creation of the Universe.
After 40 years of speculation and calculation by some of the most famous scientists in the world, the two radio engineers had stumbled upon a faint cry from our own cosmic birth.
The cause of the hiss had to be the leftover heat from the Big Bang.
A picture of the beginning of time and space was starting to emerge.
This balloon is our whole Universe. As I expand the Universe... Notice how all the things on the balloon move apart from each other.
We're not in the center of the Universe.
It's the whole Universe that's expanding -- expanding in time.
Same is true with the radiation.
It's not that the microwave radiation is coming towards us and we're in the center of the Big Bang.
The whole balloon is filled with radiation from the Big Bang.
As the balloon expands, the radiation gets colder.
Bigger the balloon, colder the Universe is. We can now run the Universe back in time. The Universe is contracting, getting hotter, getting hotter, getting hotter, hotter still. We're now back at the moment of initial singularity. We're at the moment in which the Big Bang started.
Everything -- all of space is contracted right here.
This is when the hot radiation was generated. It's not generated in one spot. It's generated everywhere.
The Big Bang happened everywhere on the surface of the balloon.
The accidental discovery of cosmic microwave background radiation earned the two radio engineers the Nobel prize for Physics.
It also gave scientists the first good estimate of when the Big Bang happened, between 12 and 14 billion years ago.
Our understanding of the Universe would never be the same.
But for David Spergel, listening to the echo of the Big Bang from a hill in New Jersey was not good enough.
He wanted to time-travel back to that first moment, when light filled the Universe, and see it.
What he needed was a rocket...
We have ignition.
A rocket which would take a picture of the earliest moment of the Universe.
It's working its way through the liftoff...
With the launch of the Wilkinson Microwave Anisotropy Probe, or WMAP, scientists were attempting to see as far back as they could, to the beginning of our world.
Spergel's dream was taking flight.
When we look at the microwave background, we're looking out in space, back in time.
We're looking back to when the Universe was only 300,000 years old.
That's the moment at which the Universe became cold enough that electrons and protons combined to make hydrogen.
Hydrogen is transparentto microwave light, so light could then travel freely from then to now.
Two years later, the results are in.
First results from NASA's Wilkinson microwave...
The WMAP delivers on its promise -- a crystal-clear baby picture of the Universe just 380,000 years
after its birth.
These pictures are worth more than a thousand words.
This is a picture of me as a baby.
Notice the high forehead, the ears, the nose... Classic smile.
Well, I'm certainly older and hopefully wiser than I was in this picture.
The basic DNA is the same.
We try to do the same thing in cosmology. We take the Universe's baby picture, and we see what it looked like when it was a few days old. We can then use that picture to look at how we got from the baby picture to the Universe we see today. But perhaps even more exciting, we can take the picture and go further back in time and learn about the Universe's beginnings, learn about where the baby came from, equivalently what happened in the first moments of the Big Bang.
The details of our birth are actually imprinted in this picture. But what happened between that moment of singularity and the AP image 380,000 years later?
For Dr. Alan Guth, a physicist from M.I.T., this missing moment in our Universe's timeline was the key to everything that came before and after the Big Bang.
The Universe that we see is, in fact, unbelievably uniform, and that's hard to understand, because conventional explosions don't behave that way.
But other scientists have different ideas about what might have happened at that moment of singularity.
The physical laws break down.
The mathematical equations just don't make sense anymore.
The beginning of time is about to get a whole lot stranger. 40 years after two radio astronomers first heard a faint whisper from our own cosmic birth, David Spergel now has his baby picture of the Universe.
Despite the vibrant colors visible in the WMAP image, it only describes a miniscule variation in temperature across the Universe. When we look at the WMAP map, what we're seeing are tiny variations in the temperature of the Universe from place to place, variations that are 1 part in 10,000, 1 part in 100,000.
So, I ink of the Universe we look at with the WMAP satellite as not being chaotic but being very ordered, homogeneous, and smooth. But if time and space started in a cataclysmic explosion of energy, wouldn't the Universe be uneven and messy in all directions?
I can't start this with "not exactly," can I? For Dr. Alan Guth, what happened during this early moment in time was an intriguing mystery that had to be solved.
Figuring this out became his life's work.
There had been in cosmology a serious problem in understanding the uniformity of the Universe.
It has the same intensity in every direction that we look to 1 part in 100,000. And that means that the Big Bang was unbelievably uniform. And that's hard to understand, because conventional explosions just don't behave that way.
We've set up a balloon that's gonna be dropped from a very high height, up there on a crane. The balloon is filled with paint, and we'll get to see what kind of a splat a typical explosion makes. So, this is what a typical explosion might look like, and as you can see, it's anything but uniform.
There are spots here and spots there and white spots in between. The early Universe was nothing like what's on the canvas here.
Alan needed something that would immediately smooth out all the hot, dense plasma that had just come into existence.
I came across this idea of inflation, the idea that gravity can, under some circumstances, act repulsively and produce a gigantic acceleration in the expansion of the Universe, and that this could have happened in the very early Universe.
The key idea behind inflation is the possibility that at least a small patch of the early Universe contained this peculiar kind of repulsive-gravity material. And all you need is a tiny patch of that, and the Big Bang starts to do this repulsive-gravity effect.
Cosmic inflation takes place right after a pop from nothing into something. About one trillion, trillion, trillionth of a second afterwards, a force field takes all the highly compressed space created in that first singular moment, which is still almost infinitely small...
And drives it out.
A tiny fraction of a second later, the Universe had doubled in size 100,000 times. A different kind of painting illustrates this idea. We're going to paint in time-lapse photography a growing sphere. Instead of getting the "splot" that we had when we just dropped the balloon, here we should see a very smooth growth of an early Universe.
With this smooth and orderly expansion, our Universe was formed.
This idea of inflation has now essentially become the standard version of cosmology, and it makes a number of predictions which have been confirmed, so it agrees very well with what we see.
With the addition of inflation, the Big Bang theory became a cohesive three-act play.
A singularity pops into existence out of nowhere and no-when, containing in one single dot all the energy that will ever be in our Universe.
Inflation suddenly takes hold -- an unimaginably rapid expansion of space smoothly spreading out that energy, bringing order to the Universe.
It's now a massive soup of evenly expanding plasma.
The Universe cools.
Matter starts to clump together under the force of gravity, eventually forming stars, galaxies, and planets.
For most cosmologists, this three-act play is the best explanation for what happened at the beginning of the Universe. But not for everybody. Interpreting this as a beginning is indeed just a crutch. It's not derived from any theory. It's just a place where the theory itself breaks down.
Dr. Martin Bojowald is a Professor of Physics at the institute for Gravitation and the Cosmos at Penn State.
He's a rising star in a new generation of cosmologists which is challenging some long-held beliefs about the Universe.
Inflation may have fixed act two, but Martin thinks the play still starts with a very unlikely act one -- the sudden and singular pop from nothing into the entire Universe.
A singularity just means we don't understand the theory well enough.
Alan Guth used the theory of inflation to dig down to a trillion, trillion, trillionth of a second after the beginning.
Martin went a million times closer.
In Bojowald's theory, time is not free-flowing, but made up of discrete, measurable chunks.
These chunks of time are called "space-time atoms." It's a very different way of thinking about what happened before the beginning. Here we have a beautiful, old grandfather clock. As we can see, there's a pendulum. It's swinging in a continuous way, thereby telling the clock how time is proceeding. They're not discrete marks, but rather a continuous motion of the pendulum.
This is the classical picture of time measured continuously.
Now, in quantized time, it's a whole different story.
For quantized time, we have a picture as given by the second hand of the clock here.
It's not continuous.
It's not the pendulum swing, which we could stop at any time, at any position.
Here, the different positions are given by certain discrete sets between one tick and the next one.
It's a finite amount of time which cannot be further subdivided.
In Bojowald's version of the early Universe, you never get to nothing.
The second hand on the quantized clock marks not just the beginning of one moment, but the end of another.
The tick that signaled dawn in our Universe marks one second past midnight in the last. So, we have this balloon Universe. If we imagine what it could have been before the Big Bang, it was collapsing, so the volume was shrinking.
Now, if we follow the usual evolution, according to general relativity, that would have been ending in a singularity.
The whole balloon would just completely deflate. But with the atomic nature of space and time, the attractive behavior of gravity changes.
It becomes repulsive at these high densities.
The collapse stops. Then the forces turn around, so there's a repulsive force which makes the Universe re-expand.
At some point --
we're not sure yet --
but it might recollapse at some time in the future, so all the air might go out again.
The volume would decrease, the density would increase, and then probably approach another Big Bang.
The Universe expands and contracts, but it never actually begins.
There could have been a series of Universes before this one and more to come after this one.
Bojowald is working through the problems and conundrums that all radical new theories face.
His theory is by no means complete, and it may never be.
We are still working on the equations.
We don't have the complete answer yet, but it seems to be the best theory yet to address these issues.
But in 2001, two of the leading cosmologists in the world published a paper suggesting an even more radical approach to what happened at the beginning.
For these two scientists, there was another answer so strange and unexpected that it had never been considered.
There are bangs and bangs and bangs forever.
Our Universe may not be the only one, but one of hundreds, thousands, maybe an infinite number.
It's an inspiring and daunting suggestion -- the Universe is an endless cycle prompted by an endless series of bangs, forever.
When you look out into space, gaze at a distant star, you also look back in time.
Light from distant galaxies can take billions of years to reach us. Now we know there's a limit to how far back we can see, an edge to the visible Universe.
The light from that cosmic backdrop has taken 13.7 billion years to make it to Earth.
What lies beyond that curtain?
According to Professor Martin Bojowald, time becomes squeezed and distorted as it nears a singularity and then bounces back out into another expansion.
But perhaps there's an altogether different way to look at what happened before the beginning.
South African scientist Dr. Neil Turok is now daring to go further into the past than almost anyone else.
His radical view of the cosmos was influenced by his parents' struggles during apartheid. My father and mother were political activists against the South African government.
They went to jail for their opinions. But ultimately, democracy came to South Africa and they were both elected members of parliament -- the only husband-and-wife members of parliament apart from Nelson and Winnie Mandela.
They served as a model of persistence.
Just because at the moment your ideas are not fashionable or agreed upon, if you believe what you're doing is right, persist.
From the moment he entered the field of theoretical physics, the South African scientist was looking for new answers to age-old problems.
There is a conventional wisdom in the field, and people are very slow to adopt new ideas. And, frankly, many people have built their careers on the status quo, and they don't want a new idea coming along and rocking the boat.
For Neil, the WMAP announcement brought up familiar feelings about seeing the Universe through a slightly different lens than some of his colleagues. In the WMAP press announcement, of course the scientists involved linked it explicitly to inflation and said, "this dramatically confirms inflation." And this made me squirm.
My point of view was that the information contained in the WMAP data was, in itself, not sufficient to prove or refute inflation.
He wasn't alone. Across the Atlantic, another intrepid scientist labored to uncover the truth behind what happened before the beginning.
Paul Steinhardt is the Albert Einstein Professor of Physics at Princeton University. As a young man, Paul was inspired to study science by the moon landings. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard.
In 1999, the two men combined forces to see if they could answer some of their problems with the inflationary model of what happened at the beginning.
Inflation had some extraordinary successes, so it's tough competition to compete with inflation. So I will not tell you all the ideas that were attempted and dumped in the wastebasket.
We have similar objectives, which is to shake the field up once in a while and come up with something bold and original and different and to improve on the status quo.
I organized a conference with Neil Turok. We had a common interest in string theory, which were just coming out at that time, whether they might stimulate some new ideas in cosmology.
String theory was developed in the last 35 years as an attempt to devise a single theory explaining everything in the Universe. In it, everything is made of minute, vibrating strings. But for the mathematics of string theory to work, there have to be more than the three dimensions of space that we see.
Rather, there are 10 dimensions, plus time.
Space-time is a flexible substance, like a membrane, and it can stretch and shrink. So, we knew these things could move, but nobody had really studied the dynamics of that process. So we brought in experts, like Burt Ovrut, who is one of the most proficient developers of particle-physics models based on string theory. And he gave a beautiful series of lectures in which he described to us this idea of our three-dimensional world being embedded in a brane world separated by a small gap from another brane world along an extra spatial dimension.
And as we sat there,we both had the same thoughts..., Which is, if you imagine that this is really the structure of the Universe, there's a new possible interpretation for what is the Big Bang.
What have we not been facing up to, you know?
What is the elephant in the room?
And the number-one question was the singularity.
We both sort of approached Burt from both ends..., And cornered Burt after his lecture..., And each of us finished the sentence of the other..., And said, "you know, well, "what about if these things collide?
What would happen then?"
"And is it possible the Big Bang is not a beginning, but is a collision?"
And his response was, "maybe."
The meeting soon broke up, but the three men had all been invited to attend the same play in London that evening. We met at the train platform, and then we began to really imagine this idea in more detail about what it would mean if the Big Bang were not a beginning but the Big Bang
were a collision. And then we had a train ride to London, where we just brainstormed about this
in a very loose and unstructured and unmathematical way.
We asked ourselves the question, "could we invent something "which was different than the inflationary picture, that was different than the standard picture?"
We had some rough ideas how to do it, but it wasn't at all obvious.
Time was flying past us as the train was moving along.
It's one of those rare occasions when you're having a conversation and you feel like a really exciting idea is emerging -- sort of that sixth sense that something important is happening. Coming up with this rough idea for how things might work is, of course, exciting.
But in having an idea like that, and then deciding to really pursue it, you are condemning yourself to years of misery, because you now have to flesh this out.
And to solve this mystery, Neil and Paul would turn to one of the toughest mental challenges of the human mind -- the incredibly strange world of 11-dimensional space...
And Universes parallel to our own.
Albert Einstein was a formidable thinker. His theories of relativity were groundbreaking developments that triggered a century of cosmic insights.
But even more fundamental was his realization that time and space are intertwined.
The three dimensions of space are really part of a four-dimensional fabric called "space-time."
But now there's a new movement in theoretical physics.
It's called "string theory." And out of string theory comes "m-theory." In m-theory, there are not four, but an astounding11 dimensions -- 10 dimensions of space plus one of time.
Uh, what is m-theory?
So, uh, m-theory is an attempt to, uh -- let me start again. Three-dimensional infinite worlds stretching off -- uh, let me start again.
Why would one even think about -- how does one make that not sound crazy in two sentences?
So, m-theory is a... Promising, unified theory of all the fundamental forces and constituents that we observe in nature.
In a sense, you could describe it as the culmination of all the developments in theoretical physics over the 20th century.
In order to make this theory work, one needs to have more than the usual three spatial dimensions, so a key idea behind m-theory is that there are more than the three dimensions of space that we experience.
There are hidden dimensions. In fact, there are seven more, and the reason we're not aware of them is that they are so, so tiny that in order to see them, you'd need an enormously powerful microscope far more powerful than any we have.
Our three-dimensional world lives in a surface embedded in a space with an extra spatial dimension that separates it from another such surface.
One possibility that springs from these extra dimensions is that this other three-dimensional world could be just a fraction of a centimeter from ours and yet hidden from our view.
These surfaces are called "branes," standing for "membrane," which is to remind us that these surfaces are elastic.
They can stretch, they can wiggle, they can warp.
They can move along this extra dimension.
All of the particles we're made of are actually curled-up little branes.
And all the dimensions of space we travel in are comprised of branes themselves.
And so everything in the Universe is composed of these geometrical objects.
I don't know if I can repeat that again.
Caution -- you have entered a place called "brane world."
We're stuck like flies on fly paper to our brane world.
We simply can't reach out into the extra dimension -- even 10 to the minus-30 centimeters -- to touch the other brane world.
It was rough this world of branes that Paul and Neil stumbled onto a potentially radical new theory of what happened before the beginning. So, here I have a piece of material, and it looks like a two-dimensional object, because one of the dimensions goes up and one goes side to side. But if we look a little bit closer at this object, and look at it from the side, you'll see that actually there are two pieces of material, separated by a tiny gap. And you could think of this gap as being the fourth dimension of space. And the collision of these two three-dimensional worlds -- the one we live in and another one -- would have been the Big Bang.
It would be a collision, instead of a springing from nothingness.
So, if the branes existed before and after, that means space and time existed before.
They could have helped set up the conditions we observe in the Universe today -- they collide, and they move apart again.
The Big Bang is not the beginning.
That means we have more time to solve all the cosmological problems that inflation was designed to solve. So, we began to imagine, "could we replace that idea with something that occurred before The Bang?" And as we were going along the train ride, we began to imagine lots of possibilities, so that by the end, it seemed like a very exciting alternative to the standard Big Bang inflationary picture.
For the next 18 months, the three men and another physicist, Justin Khoury, worked feverishly to clarify and justify their initial spark of creativity.
Now we had to make the mathematics work, and this involved developing a lot of new physics to explain the motion of branes moving along extra dimensions under the influence of a force which is trying to draw them together.
This mathematics didn't exist before.
A new theory of the Universe starts to come alive.
The picture we had in mind was two three-dimensional worlds stretching off to infinity but separated from each other by a tiny gap -- a fourth dimension of space.
The two three-dimensional worlds are actually pulled together by a very, very weak force.
The force has to be very, very weak, otherwise the bang would occur too quickly.
We know that the cycles can't be too short, because the Universe has already gone 14 billion years since the last bang.
A trillion years is probably a good, you know, typical value for what we expect the length of a cycle to be.
As the branes approach, the force gets stronger and stronger. And when they collide, kinetic energy of the branes is then converted into the hot radiation that fills both three-dimensional worlds and looks like the Big Bang.
So that when the branes move apart again, they're now filled with the matter and radiation that was created at the collision. This then causes the branes to begin to expand again and cool, creating a new period of expansion, cooling, creation of new atoms, molecules, stars, and galaxies.
We now had an explanation for the Big Bang.
This is normally referred to as "cosmic singularity" -- some sort of breakdown in the laws of physics, which in the standard Big Bang theory, you simply ignore. But in this picture, you are actually providing an explanation for it. It was, in fact, the collision between these two brane worlds. It was a theory of what was the cosmic singularity. It was a radical and elegant solution to one of the great cosmic mysteries of all time.
According to Neil and Paul and their colleagues Burt and Justin, there was always a time before time. After almost two years of work, it was time to present this new theory to their fellow scientists.
At a conference in Finland, the two physicists laid out their theory.
The reception was icy.
The criticism was that we were simply assuming or asserting the branes would be flat and parallel to begin with without showing why that should be the case. We'd been so excited about this idea, and yet everyone else was just poo-pooing it.
To be fair, I mean, the session did not go well for us. The next morning, we were both rather depressed, so we began to travel along the River near Rovaniemi and have this discussion about "what could we replace this idea with?"
So, we began to think about something that wasn't yet included in the theory, which was the idea of dark energy.
Dark energy is a recent and totally surprising astronomical discovery -- a mysterious force that's causing the Universe to expand even faster.
Eventually, the dark energy will expand the Universe so much that it will be nothing but cold and empty space.
In the language of m-theory, that translates to a flat brane.
The dark-energy phase stretches out the three-dimensional worlds and makes them very flat and very empty and very parallel. Of course, that immediately clicked with another idea.
Well, we're using something now, but we're using it before the bang.
Well, maybe the source of dark energy then was actually the same as the one now and the Universe is cyclic somehow.
So, you could have a bang followed by a normal period of the Universe, like we live in today, followed by a second bang in our future, followed by another bang, and so on.
There are bangs and bangs and bangs forever.
Their theory was now complete.
Two branes come together, inject one another with energy, then dark energy takes a trillion years or so to spread that energy out.
The branes flatten and then come together again.
This cycle happens endlessly.
Neil Turok and Paul Steinhardt had come up with a remarkable alternative theory to the Big Bang and cracked the door onto what happened before the beginning.
As different as the models are, they produce the same exact variations in the background radiation.
The same WMAP image fits both ideas.
It's truly the case that when WMAP made its announcement, the way most people interpreted that announcement was, it's beautifully consistent with the Big Bang inflationary picture.
To us, it meant that the cyclic model was in the game as much as inflation was. But which theory is right?
The answer to one of the biggest cosmic mysteries of all -- was there a time before our time? -- could be circling the Earth a million miles over our heads.
What happened before the beginning?
The question is posed. Sides are drawn.
The closing arguments are being prepared.
Is the answer "nothing"?
Did a Big Bang suddenly and inexplicably burst into life from a time of no-when and a place of nowhere?
Or could we have bounced from the contraction of another Universe that existed before ours?
Or are we living a trillionth of a trillionth of the width of an atom away from a parallel Universe, and every trillion years, these parallel worlds bump into one another and fill each other up with huge amounts of energy and matter?
Professor Martin Bojowald's bouncing Universe is still a work in progress, but for proponents of the cyclic and the Big Bang inflation model, the answer to how and when the Universe started may be moving toward us across time and space like tiny ripples in the cosmic ocean..., Gravitational waves.
Gravitational wave is pretty much like a sound wave. We're used to a sound wave traveling from me to you as I speak, as a compression and expansion of the air between us. And so the molecules get more densely packed and further apart as the wave moves from me to you.
But gravitational waves ripple not air molecules, but space itself, which means that they can stretch out or compress a beam of light and cause a shift in its color.
So, if space is expanded, we'll see the radiation shifted to red frequencies, longer wavelengths.
But if it's coming towards us, we'll see it's slightly bluer than it would otherwise have been. And so, by carefully analyzing the pattern of radiation on the sky, we can, in fact, infer if there are gravitational waves traveling through our part of the Universe. And rocket technology will get the scientists far enough up into space to espy these gravitational waves. The Planck satellite is the successor to WMAP. It will be measuring the sky with about twice the resolution and about 10 times the sensitivity.
The Planck satellite is really the first device we have which seems to have a strong capability of maybe finding"these gravity waves. And if we're lucky, that'll tell us what happened during the first moments of the Big Bang, or maybe even before.
For proponents of The Big Bang inflation model, finding significant gravitational waves would be the final step in proving that there was a giant expansion of whooshing energy from a place of nowhere and no-when.
But Paul Steinhardt and Neil Turok are also looking forward to the Planck satellite results.
In their cyclic model of the beginning of the Universe, two branes coming together would be a much less intense collision, and the chances are that gravitational waves would be almost nonexistent.
If we observe these gravitational waves in the Planck satellite, that will support the inflationary theory and rule out the cyclic picture.
And conversely, if we don't see them, that would strongly support the cyclic picture.
But no matter which description of the beginning of the Universe appears to be more accurate, the true winner will be our own scientific understanding.
Yeah, to me,it's man against nature.
We're trying to figure out nature's secrets.
If we're lucky, we'll be surprised. These tiny, almost undetectable waves will have a tsunami-like effect on the future direction of cosmology. Instead of appearing from nowhere and no-when and rising from stardust to humankind, we may have to consider the mind-boggling premise that we are just the latest version of an endless series of Universes.
We still might not know what happened before the beginning...
But we would know that something did.
The final answer may be close at hand.