[12/4/05] The Fabric of Our Universe
by Petr Kuzmic
December 4, 2005
Throughout history, science and religion have been asking the same big questions. When and how did our universe come into existence? What, if anything, existed before that? Is the Milky Way a river, as in our children's story today? In the words of our hymn, who or what is the "Dear Weaver of our lives' design"?
Today I'd like to talk about three things. One, what does current science know about the very beginnings of the universe. Two, what does science know about the long-term fate of our universe. And finally, as a working scientist and a religious humanist, I'd like to share a few reflections on how current cosmological research influenced my philosophical and ethical beliefs.
The first question on our list is what does current research tell us about the very beginning of the universe. The simple answer is: nothing, nothing at all. Now, by the very beginning of the universe I mean the exact moment at which it appeared, technically speaking "time zero". We do know that our universe came into being very abruptly in something like the Big Bang, but current physical theories say literally nothing about that particular moment. Physics begins its story very shortly after that, a tiny fraction of a second after "time zero". It is a very short amount of time, but currently accepted research has nothing to tell us about what happened before that short fraction of a second elapsed.
We could talk for a long time about the technical reasons why there is this problem. We could talk about "singularities" in solving general relativity equations. We could talk about the profound contradictions between two branches of physics, general relativity and quantum theory. We could talk about efforts to create a Grand Unified Theory, where these internal contradictions in physics would be resolved, so we could at least start talking sensibly about the very beginning of the universe. But the fact is, at this moment we don't have a widely accepted physical theory applicable to the very early universe.
One prominent theoretical physicist, Brian Greene, puts is this way in one of his popular books, The Fabric of the Cosmos:
Now let's turn to our next question: what is the long-term fate of our universe. In that area, we actually know quite a bit, and a lot of it was learned in the last six or seven years. The main message seems to be that, in the long term, things won't stay as they are now.
First of all, it's been known for a long time that, in a few billion years, our sun will turn into something called a "red giant", envelop the entire solar system, and in the process incinerate our planet. That's a big change, I would say... You may say that a billion years is an unimaginably long period of time, but I'll try to show that it isn't. Let's play a little mathematical game. Let's use as our yardstick the duration of one average human life, say 75 years. Let's measure with this yardstick how far into the past we could reach, if we could ever stagger the lives of a certain number of people.
So, how far into the past we could reach if staggered the number of people who could fit into this room, let's say 130 people? Well, 75 x 130 is about ten thousand years. That's much farther back than to the arrival of first Europeans in America. It's much farther back than to the Egyptian pyramids. In fact, we could reach back in time to the most recent ice age. And one billion years is only the number of staggered human lives of people currently living in New York City, so in some respects it's not a very long time at all.
Aside from our little corner of the Milky Way getting swallowed by the sun in not too distant future, things will not stay the same even in the much larger cosmic neighborhood. Already in 1929, Edwin Hubble discovered that our universe is expanding. That was probably the second most important revolution in astronomy, after Copernicus discovered that the Earth goes around the Sun, and consequently we humans are not the center of the universe. In fact, not only we are not in the center of the universe anymore, but the universe also is being inflated under our feet, like one giant birthday balloon.
For several decades after Hubble's discovery, the question was whether the expansion will continue forever, or will it eventually stop and reverse itself. In the second case, the universe might eventually collapse on itself because of gravitation and perhaps begin a new cycle in a giant explosion. Well, now we know. Based on very precise astronomical measurements conducted between 1998 and 2003, the answer is in, at least tentatively. The answer is, not only is only our universe actually expanding faster and faster as time goes on, but also the amount of matter and energy in the universe suggests that it will never stop expanding.
But what could it mean to say the universe will "never stop expanding"? What will happen with the fabric of our universe, as the threads continue to be pulled apart? The answer to this question has to do with Albert Einstein and his special theory of relativity published in September 1905, almost exactly a hundred years ago.
If you can imagine somehow stretching a piece of regular fabric as our universe expands, first the threads would come apart; then the tiny fibers of cotton or silk in each thread; then the molecules in each fiber, then the atoms in each molecule and so on. Eventually, even subatomic elementary particles would be pulled apart into constituent pieces. But where would all this material go? This is where Einstein comes in, with his equivalence between matter and energy, the famous "E equals M C squared" equation. The very early or young universe was composed mostly of energy (meaning radiation, or light) but very little or no mass. Our own middle-age universe happens to have both mass and energy in it, but as the fabric of the cosmos continues to be pulled apart and stretched, an old-age universe will return to a state of pure energy or radiation.
Here is how Brian Greene puts it:
I remember how I felt when I first learned about the inevitable end of all life on our planet, after the sun grows into a giant fireball. I felt horrified and panicked, even though I knew this would happen long after I am gone.
I realized then how much of my core beliefs were based on the assumption that life, which started in our nook of the Milky Way, will go on forever. And if not here, then somewhere else. Apparently I believed in a humanist equivalent of the eternal soul; I believed in some humanist equivalent of the final judgment; and I was placing the reference point in my ethical universe not here and now, but to a very distant time. I was basing my faith in an eternally unbroken chain of future generations, just like revealed religious traditions place their faith in an eternally unchanging God, a source of ultimate moral authority, who will forever judge our actions.
The most recent results in cosmology and theoretical physics focused my attention again on the here and now. I no longer look to eternity as a reference point. This, here and now, my friends, is really all we have however briefly. We now know that everything material is temporary on at least three different scales of time. We always knew that our individual human lives don't last forever. We've know for few decades that our earthly home inevitably will come to an end, as soon as our sun's lifecycle is completed. This will happen in a relatively short amount of time, a time it would take for all the inhabitants of a small handful of major cities to live out their lives one after another.
But now we also know that all matter in the universe will be converted back into pure energy. The fabric of our forever-expanding universe will be gently pulled apart into its constituent threads. The atoms of matter themselves will be gently pulled apart into its constituent particles, and ultimately all matter will disappear: only a faint mist of pure light will remain.
I myself don't find this vision discouraging. I hope that being increasingly aware of my own temporary nature, and of the temporary nature of all matter in the universe, will continue to encourage me to get up in the morning and do what needs to be done.
Amen and blessed it be.
December 4, 2005
Throughout history, science and religion have been asking the same big questions. When and how did our universe come into existence? What, if anything, existed before that? Is the Milky Way a river, as in our children's story today? In the words of our hymn, who or what is the "Dear Weaver of our lives' design"?
Today I'd like to talk about three things. One, what does current science know about the very beginnings of the universe. Two, what does science know about the long-term fate of our universe. And finally, as a working scientist and a religious humanist, I'd like to share a few reflections on how current cosmological research influenced my philosophical and ethical beliefs.
The first question on our list is what does current research tell us about the very beginning of the universe. The simple answer is: nothing, nothing at all. Now, by the very beginning of the universe I mean the exact moment at which it appeared, technically speaking "time zero". We do know that our universe came into being very abruptly in something like the Big Bang, but current physical theories say literally nothing about that particular moment. Physics begins its story very shortly after that, a tiny fraction of a second after "time zero". It is a very short amount of time, but currently accepted research has nothing to tell us about what happened before that short fraction of a second elapsed.
We could talk for a long time about the technical reasons why there is this problem. We could talk about "singularities" in solving general relativity equations. We could talk about the profound contradictions between two branches of physics, general relativity and quantum theory. We could talk about efforts to create a Grand Unified Theory, where these internal contradictions in physics would be resolved, so we could at least start talking sensibly about the very beginning of the universe. But the fact is, at this moment we don't have a widely accepted physical theory applicable to the very early universe.
One prominent theoretical physicist, Brian Greene, puts is this way in one of his popular books, The Fabric of the Cosmos:
"We don't know what the initial conditions of the universe were, or even the ideas, concepts, and language that should be used to describe them. No one has any insight on the question of how things actually did begin. In fact, our ignorance persists on an even higher plane: We don't even know whether asking about the initial conditions [...] lies forever beyond the grasp of any theory."
Now let's turn to our next question: what is the long-term fate of our universe. In that area, we actually know quite a bit, and a lot of it was learned in the last six or seven years. The main message seems to be that, in the long term, things won't stay as they are now.
First of all, it's been known for a long time that, in a few billion years, our sun will turn into something called a "red giant", envelop the entire solar system, and in the process incinerate our planet. That's a big change, I would say... You may say that a billion years is an unimaginably long period of time, but I'll try to show that it isn't. Let's play a little mathematical game. Let's use as our yardstick the duration of one average human life, say 75 years. Let's measure with this yardstick how far into the past we could reach, if we could ever stagger the lives of a certain number of people.
So, how far into the past we could reach if staggered the number of people who could fit into this room, let's say 130 people? Well, 75 x 130 is about ten thousand years. That's much farther back than to the arrival of first Europeans in America. It's much farther back than to the Egyptian pyramids. In fact, we could reach back in time to the most recent ice age. And one billion years is only the number of staggered human lives of people currently living in New York City, so in some respects it's not a very long time at all.
Aside from our little corner of the Milky Way getting swallowed by the sun in not too distant future, things will not stay the same even in the much larger cosmic neighborhood. Already in 1929, Edwin Hubble discovered that our universe is expanding. That was probably the second most important revolution in astronomy, after Copernicus discovered that the Earth goes around the Sun, and consequently we humans are not the center of the universe. In fact, not only we are not in the center of the universe anymore, but the universe also is being inflated under our feet, like one giant birthday balloon.
For several decades after Hubble's discovery, the question was whether the expansion will continue forever, or will it eventually stop and reverse itself. In the second case, the universe might eventually collapse on itself because of gravitation and perhaps begin a new cycle in a giant explosion. Well, now we know. Based on very precise astronomical measurements conducted between 1998 and 2003, the answer is in, at least tentatively. The answer is, not only is only our universe actually expanding faster and faster as time goes on, but also the amount of matter and energy in the universe suggests that it will never stop expanding.
But what could it mean to say the universe will "never stop expanding"? What will happen with the fabric of our universe, as the threads continue to be pulled apart? The answer to this question has to do with Albert Einstein and his special theory of relativity published in September 1905, almost exactly a hundred years ago.
If you can imagine somehow stretching a piece of regular fabric as our universe expands, first the threads would come apart; then the tiny fibers of cotton or silk in each thread; then the molecules in each fiber, then the atoms in each molecule and so on. Eventually, even subatomic elementary particles would be pulled apart into constituent pieces. But where would all this material go? This is where Einstein comes in, with his equivalence between matter and energy, the famous "E equals M C squared" equation. The very early or young universe was composed mostly of energy (meaning radiation, or light) but very little or no mass. Our own middle-age universe happens to have both mass and energy in it, but as the fabric of the cosmos continues to be pulled apart and stretched, an old-age universe will return to a state of pure energy or radiation.
Here is how Brian Greene puts it:
"In the far, far future, essentially all matter will have returned to energy. But because of the enormous expansion of space, this energy will be spread so thinly that it will hardly ever convert back to even the lightest particles of matter. Instead, a faint mist of light will fall for eternity through an ever colder and quieter cosmos. The guiding hand of Einstein's E = mc² will have finally come to rest."
I remember how I felt when I first learned about the inevitable end of all life on our planet, after the sun grows into a giant fireball. I felt horrified and panicked, even though I knew this would happen long after I am gone.
I realized then how much of my core beliefs were based on the assumption that life, which started in our nook of the Milky Way, will go on forever. And if not here, then somewhere else. Apparently I believed in a humanist equivalent of the eternal soul; I believed in some humanist equivalent of the final judgment; and I was placing the reference point in my ethical universe not here and now, but to a very distant time. I was basing my faith in an eternally unbroken chain of future generations, just like revealed religious traditions place their faith in an eternally unchanging God, a source of ultimate moral authority, who will forever judge our actions.
The most recent results in cosmology and theoretical physics focused my attention again on the here and now. I no longer look to eternity as a reference point. This, here and now, my friends, is really all we have however briefly. We now know that everything material is temporary on at least three different scales of time. We always knew that our individual human lives don't last forever. We've know for few decades that our earthly home inevitably will come to an end, as soon as our sun's lifecycle is completed. This will happen in a relatively short amount of time, a time it would take for all the inhabitants of a small handful of major cities to live out their lives one after another.
But now we also know that all matter in the universe will be converted back into pure energy. The fabric of our forever-expanding universe will be gently pulled apart into its constituent threads. The atoms of matter themselves will be gently pulled apart into its constituent particles, and ultimately all matter will disappear: only a faint mist of pure light will remain.
I myself don't find this vision discouraging. I hope that being increasingly aware of my own temporary nature, and of the temporary nature of all matter in the universe, will continue to encourage me to get up in the morning and do what needs to be done.
Amen and blessed it be.
posted by UUCP Sermons at 9:28 PM
