Posted on 02/19/2011 1:59:12 AM PST by LibWhacker
Modern cosmology theory holds that our universe may be just one in a vast collection of universes known as the multiverse. MIT physicist Alan Guth has suggested that new universes (known as “pocket universes”) are constantly being created, but they cannot be seen from our universe.
In this view, “nature gets a lot of tries — the universe is an experiment that’s repeated over and over again, each time with slightly different physical laws, or even vastly different physical laws,” says Jaffe.
Some of these universes would collapse instants after forming; in others, the forces between particles would be so weak they could not give rise to atoms or molecules. However, if conditions were suitable, matter would coalesce into galaxies and planets, and if the right elements were present in those worlds, intelligent life could evolve. Some physicists have theorized that only universes in which the laws of physics are “just so” could support life, and that if things were even a little bit different from our world, intelligent life would be impossible. In that case, our physical laws might be explained “anthropically,” meaning that they are as they are because if they were otherwise, no one would be around to notice them.
MIT physics professor Robert Jaffe and his collaborators felt that this proposed anthropic explanation should be subjected to more careful scrutiny, and decided to explore whether universes with different physical laws could support life.
The MIT physicists have showed that universes quite different from ours still have elements similar to carbon, hydrogen, and oxygen, and could therefore evolve life forms quite similar to us, even when the masses of elementary particles called quarks are dramatically altered.
Jaffe and his collaborators felt that this proposed anthropic explanation should be subjected to more careful scrutiny, so they decided to explore whether universes with different physical laws could support life. Unlike most other studies, in which varying only one constant usually produces an inhospitable universe, they examined more than one constant.
Whether life exists elsewhere in our universe is a longstanding mystery. But for some scientists, there’s another interesting question: could there be life in a universe significantly different from our own?
In work recently featured in a cover story in Scientific American, Jaffe, former MIT postdoc, Alejandro Jenkins, and recent MIT graduate Itamar Kimchi showed that universes quite different from ours still have elements similar to carbon, hydrogen, and oxygen, and could therefore evolve life forms quite similar to us. Even when the masses of the elementary particles are dramatically altered, life may find a way.
“You could change them by significant amounts without eliminating the possibility of organic chemistry in the universe,” says Jenkins.
Although bizarre life forms might exist in universes different from ours, Jaffe and his collaborators decided to focus on life based on carbon chemistry. They defined as “congenial to life” those universes in which stable forms of hydrogen, carbon and oxygen would exist.
“If you don’t have a stable entity with the chemistry of hydrogen, you’re not going to have hydrocarbons, or complex carbohydrates, and you’re not going to have life,” says Jaffe. “The same goes for carbon and oxygen. Beyond those three we felt the rest is detail."
They set out to see what might happen to those elements if they altered the masses of elementary particles called quarks. There are six types of quarks, which are the building blocks of protons, neutrons and electrons. The MIT team focused on “up”, “down” and “strange” quarks, the most common and lightest quarks, which join together to form protons and neutrons and closely related particles called “hyperons.”
In our universe, the down quark is about twice as heavy as the up quark, resulting in neutrons that are 0.1 percent heavier than protons. Jaffe and his colleagues modeled one family of universes in which the down quark was lighter than the up quark, and protons were up to a percent heavier than neutrons. In this scenario, hydrogen would no longer be stable, but its slightly heavier isotopes deuterium or tritium could be. An isotope of carbon known as carbon-14 would also be stable, as would a form of oxygen, so the organic reactions necessary for life would be possible.
The team found a few other congenial universes, including a family where the up and strange quarks have roughly the same mass (in our universe, strange quarks are much heavier and can only be produced in high-energy collisions), while the down quark would be much lighter. In such a universe, atomic nuclei would be made of neutrons and a hyperon called the “sigma minus,” which would replace protons. They published their findings in the journal Physical Review D last year.
Jaffe and his collaborators focused on quarks because they know enough about quark interactions to predict what will happen when their masses change. However, “any attempt to address the problem in a broader context is going to be very difficult,” says Jaffe, because physicists are limited in their ability to predict the consequences of changing most other physical laws and constants.
A group of researchers at Lawrence Berkeley National Laboratory has done related studies examining whether congenial universes could arise even while lacking one of the four fundamental forces of our universe — the weak nuclear force, which enables the reactions that turn neutrons into protons, and vice versa. The researchers showed that tweaking the other three fundamental forces could compensate for the missing weak nuclear force and still allow stable elements to be formed.
That study and the MIT work are different from most other studies in this area in that they examined more than one constant. “Usually people vary one constant and look at the results, which is different than if you vary multiple constants,” says Mark Wise, professor of physics at Caltech, who was not involved in the research. Varying only one constant usually produces an inhospitable universe, which can lead to the erroneous conclusion that any other congenial universes are impossible.
One physical parameter that does appear to be extremely finely tuned is the cosmological constant — a measure of the pressure exerted by empty space, which causes the universe to expand or contract. When the constant is positive, space expands, when negative, the universe collapses on itself. In our universe, the cosmological constant is positive but very small — any larger value would cause the universe to expand too rapidly for galaxies to form. However, Wise and his colleagues have shown that it is theoretically possible that changes in primordial cosmological density perturbations could compensate at least for small changes to the value of the cosmological constant.
In the end, there is no way to know for sure what other universes are out there, or what life they may hold. But that will likely not stop physicists from exploring the possibilities, and in the process learning more about our own universe.
"...there is no way to know..."
"...that will likely not stop physicists from exploring the possibilities..."
I agree that there is no way to know. Therefore, there can be no "exploring." What they are doing is speculating about the existence of something which cannot be proven or disproven. How does this help us to "learn more about our own universe"? This is not science. It is not even science fiction. It is meaningless fantasy, a total waste of time.
A thesis which, by definition, cannot be verified, quantified or falseified. And they call this science?
There is no shortage of material to study or contemplate, already "here".
Science is about disprovable hypotheseses.
But a many-Universe theory isn't disprovable. Moreover: it is strictly non-provable, which puts such a theory in a very special class of short-bus scientific endeavours. This is because - by definition - a different Universe must be orthogonal in all ways to this Universe.
So if you can detect or observe any part of a 'different Universe' then - by definition - what you have observed is actually part of your own Universe..
So for instance: different dimensions, different 'branes', phase-spaces of existance with different physical laws - if you can find them, then they are not a different Universe - they are simply proofs that the current Universe is more extended and more extraordinary than previously thought.
What is religion, if not a belief that there is a separate universe of which we can be conscious, and in which we can spend time?
This is because it allows them to run from the glaringly obvious conclusions of the Strong Anthropic Principle.
In brief, the Strong Anthropic Principle concerns the colossal variable space that a Universe might have - and how the Universe in fact has exactly the correct variable set that allows:
* Three dimensional space to exist for 9+ Billion years
* Protonic matter to exist for 9+ Billion years
* Atoms to exist for 9+ Billion years
* Carbon and iron to exist
* Life to exist in any way, shape or form.
Example: vary one single nuclear resonance value by a vanishingly small fraction, and Carbon would be as rare as Mendelevium.
Because the Strong Anthropic Principle points directly to 'Intelligent Design', certain kinds of scientists instead insist that there must be quadrillions of different Universes sampling all parts of the Universe variable space - and that we happen to inhabit the only one of those quadrillions of Universes where life can exist.
Which is (as I say) non-disprovable, and also non-provable. Multiple Universe Theory requires a level of belief that e.g. Christian belief does not.
For instance: Christianity could be proved absolutely to all unbelievers in the next four minutes by the Second Coming. But Multiple Universe Theory cannot be proven - ever - not even after the last syllable of recorded time.
Many who have had a near death experience witnessed the many apertures that led to and away from the light.
They weren't going to or from the same locations for heaven's sake!
Every time I see Obama reading from his teleprompter...
It is obvious, there are alternate universes.
It's a fair question. A religious theory and Multiple Universe Theory differ in this: the other Universes predicated by MUT are places that, even if they exist, cannot ever be interacted with.
Even if MUT were true (and how could we ever know?) we could not ever spend time there, in the same rigorous sense that 1 cannot equal 2.
But a religious theory, if it is in fact a true religious theory, can be realized. One day, we may indeed find ourselves in Paradise.
Ok... am I the only knumbskull? How can there be more than 1 and still be a Universe?
TT
That is my Favorite Picture ... my new monitor however does not ever get me the detail that my old one did, or I just don’t have the right image.
Da Vinci has the most Famous drawing the Vitruvian Man and the Most Famous Painting the Mona Lisa but the most incredible picture,the most mind blowing important image to date is the Hubble Deep Space Picture ... and it’s Billions of Years Older as well.
TT
It is fun looking back in time billions of years, then comparing the present to the past. Makes one wonder what is going on in the present. More precisely, here on earth, the present, looking through Hubble, is linked with with the past, therefore is the earth actually in the present or past? No offense intended, just being playful this AM.
Yes, it can be fun looking back in time, for instance at andromeda V73 or pulsar 445 W3, or even globular cluster 576T, but sometimes it can be hard to dig up some of those old memories, too.
and wouldn’t it be nice to see the present at these locations? Memories, sweet memories.
Can the existence of God be proven or disproven, demons, angels, elves, etc?
Who cares?
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