Theory of Everything?
Posted on: March 21, 2010 - 7:58pm
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Theory of Everything?
I'm wondering what you guys think about the pursuit by physicists of a Theory of Everything (TOE). What I wonder is if they aren't doing something similar to what theologians are trying to do, namely argue for that "one special thing" that explains it all. Admittedly physicists do not use vague notions like theologians do, and aren't after something to beat people over the head with (aka support for their bible). But it does seem like they both assume there has to be One Answer. Why can't there be "two things"?
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I think it is the hope for parsimony. If there is only one fundamental "thing" at the base of it all, then we have the single base model from which everything else is derived. Perhaps then we will not only be able to model the physical universe, but understand it completely. At least, understand what makes up all the effects we observe.
The "Theory of Everything" (should it exist) may be more complex than a single thing. It might be two or more things interacting at the planck scale, for instance. At the moment, we have no way to know, as we don't even understand quantum mechanics.
Perhaps we'll never know.
"Yes, I seriously believe that consciousness is a product of a natural process. I find that the neuroscientists, psychologists, and philosophers who proceed from that premise are the ones who are actually making useful contributions to our understanding of the mind." - PZ Myers
Physics can never produce a ToE. They may well eventually get a comprehensive theory of mass/energy and particle interactions, integrating Relativity and Quantum Mechanics, which would provide an accurate predictive model of the behaviour of the Universe at the most elemental level of description.
It does not help us understand and explain the dynamics of evolution, the psychology of human beings, the origin and nature of consciousness, etc.
For illustration, the comprehensive understanding of the electronics of semiconductors is utterly irrelevant to Computer Science, even though modern computers are totally dependent on such devices. After all, they could in principle be implemented with micro-mechanical devices, or hydraulic systems, which would have zero impact on the information flow, apart from possible making it harder to achieve the speed and compactness of modern systems.
Arguably Information Theory is more fundamental than Physics. Physics is dependent on Information Theory, but Information Theory is not dependent on Physics.
So I wince whenever a physicist uses that phrase, however appropriate it may be within the realm of Physics, which does truly provides the ground on which many other, but not all, fields of science are built.
Favorite oxymorons: Gospel Truth, Rational Supernaturalist, Business Ethics, Christian Morality
"Theology is now little more than a branch of human ignorance. Indeed, it is ignorance with wings." - Sam Harris
The path to Truth lies via careful study of reality, not the dreams of our fallible minds - me
From the sublime to the ridiculous: Science -> Philosophy -> Theology
I guess that's it - parsimony. I just wonder if any physicists have ever argued that parsimony only goes so far. That probably wanders into Philosophy of Science. I mean it could just be there are the "three forces as aspects of one" + gravity, and that's the way it is.
Yah, the ToE is probably not the best choice of words. But then physics is certainly not immune to poorly worded concepts. Another one that grates on me is when Leon Lederman refers to the Higgs boson as “the god particle”.
As far as the question of physicists having speculated on the limits of parsimony, I am reminded of a particular quote:
That would seem to apply rather well.
As far as understanding the ToE, it might help to know just what is meant by “everything”. Basically, it will be the much sought after unified field theory which will generalize the four forces of nature. Except that it now seems that astronomers may have found evidence for a possible fifth force which is driving the expansion of the universe. Generally, that is being called either dark energy or the cosmological constant. Whatever it is called, the name is just a placeholder for something that there is strong evidence for the existence of but nobody really knows anything about. So it referes to a limited concept of everything.
A better question might be to ask if physics can ever be completed. There are of course two camps on this but I tend to side with the view that it probably will never be completed.
On the practical side, there are some questions that we think are too difficult to answer. We know just about what the LHC will do for us and we know that it has specific limits. Even the failed SSC collider would not have been big enough to do everything that physicists would like to check on.
On the theoretical side, it might be well to remember, as Stephen Hawking has pointed out, that a fully complete physical theorem would be a set of equations. Physics is math and we have known for like eighty years that math cannot be completed.
On the philosophical side, physics is math and it depends on certain constants. But why are those constants precisely what they are? Much has been made of the anthropological argument that if those constants were different, life as we know it would not be possible.
However, that conjecture always assumes that the constants would be sufficiently different to make life impossible. Yah, if the fine structure constant was 5% different, that would be true. However, if the fine structure constant were 0.00005% different, we could still be here to ask the question. But what would the answer to the question be?
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There's already a multitude of answers to the physical nature of the Universe. Many of said "answers" (or theories) will readily disagree with each other*. There is a point in which two theories, developed separately, but in a symmetric manner, and in regards to very similar, deeply interconnected subject matter... will inevitably disagree with each other on specifics.
As near as I can tell, ToE is apparently the (highly unweildy) attempt for a full (and comprehensive) mathematical understanding of ALL the currently theorized physical phenomena in the Universe.
*an important exception would be mathematical constants
Disagreed; staunchly.
(apparently) You are confusing the actual "Theory of Everything (physics)" with a literal "Theory of Everything". And even if you're not...
...the problem with "never", in this case, is that it inherently makes painful assumptions:
In any case, "never", with regards to the limits of human science, is a faulty premise.
“A meritocratic society is one in which inequalities of wealth and social position solely reflect the unequal distribution of merit or skills amongst human beings, or are based upon factors beyond human control, for example luck or chance. Such a society is socially just because individuals are judged not by their gender, the colour of their skin or their religion, but according to their talents and willingness to work, or on what Martin Luther King called 'the content of their character'. By extension, social equality is unjust because it treats unequal individuals equally.” "Political Ideologies" by Andrew Heywood (2003)
Yes and no. There has always been a cutting edge of human understanding and where we are looking into the great unknown, there are often several explanations that are irreconcilable. Any of them may be the right explanation and all of them may be wrong. However, with enough work, eventually, the scientific community will, in due time, come to a general agreement on matters. At that point, all of the explanations that were not spot on will end up in the dust bin.
No. As bobspence1 has observed, physics is only valid for what it is valid for. For example, the ToE as it may one day work out to be will simply never be able to predict the weather. Or human behavior.
Such things are, while based in physics, also dependent on chaos theory, emergent behavior and possibly other factors which would be outside of the domain of any possible ToE.
While I cannot speak for bobspence1, I suspect that he was not confused on the matter. Rather, I see an interpretation where he was speaking to the awkward language of the term ToE. It is clearly subject to misinterpretation on the part of people who don't really stay on top of this stuff.
A case in point could be that some theists have jumped on the anthropic principal as an argument for design. In fact, it simply does not speak to the matter of design. Rather, it is simply an assertion that the universe exists in a certain way. It has in fact been used to advance out understanding of why there are elements other than hydrogen. In that respect, it has been quite sucessful.
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I work with and talk to physicists every day, and I have never, not even once, heard any of them talk about "Theory of everything". It sounds like a label a journalist would slap on what physicists would call unified field theories, which they do talk about. Of course, there are many and the label gets attached to things that might not overlap in ambition or application. What they want is a coherent framework that incorporates all the forces of nature and how they behave as a function of energy scale. That isn't everything, it would just tell us an awful lot about interactions at the most basic level.
They often talk about "Grand Unified Theories", however.
That seems like a more approachable goal, it must be said.
The LHC detector teams will be looking for evidence of new particles in what their detectors pick up. They are expected to either be (1) extremely evanescent or (2) very weakly interacting, so the detectors will only see their decay products. Furthermore, the collisions will produce numerous other particles, which can make it difficult to discern the desired particles.
Higgs particles - these are expected to have some nonzero ground-state/vacuum field values, making them always present, as it were. This is expected to cause the particles they interact with to get their masses.
Supersymmetry partners - supersymmetry relates particles with different spins, though no particle is known that is a supersymmetry partner of another known particle. But if such particles exist, the LHC ought to be able to produce them.
If these particles are found, then one can extrapolate to Grand Unified Theory energy scales and find out how much gets unified. However, GUT energies are about 2*10^(16) GeV, over a trillion times greater than what the LHC can reach, so it will be difficult to do direct experimental tests of GUT-scale physics.
As to a "Theory of Everything", a favorite candidate over the last couple of decades has been string theory. One can get gravity out of it, and one can get much of the Standard Model out of it, but the Standard Model is far from unique as a string-theory solution. String-theory energy scales are expected to be above GUT energy scales, making it even worse than GUT's for direct experimental tests of stringiness.
I do indeed have a problem when physicists use the phrase "Theory of Everything", since it certainly suggests to the outsider that it is about as comprehensive as you can get.
"Grand Unified Theory" doesn't quite have those implications, and is more appropriate as referring to the unification of the fundamental forces of particle physics.
From what I understand, the ToE refers to a theory combining the GUT with General Relativity/Gravity.
That still doesn't cover such areas as the theories of complex systems and information theory, which are independent of the ToE, altho it is arguable that the ToE is the one dependent on such independent disciplines, just as it is most definitely dependent on Maths, as are Complex Systems and Information Theory.
Favorite oxymorons: Gospel Truth, Rational Supernaturalist, Business Ethics, Christian Morality
"Theology is now little more than a branch of human ignorance. Indeed, it is ignorance with wings." - Sam Harris
The path to Truth lies via careful study of reality, not the dreams of our fallible minds - me
From the sublime to the ridiculous: Science -> Philosophy -> Theology
I already know how the scientific method works, Answers.
I was responding to the OP in as general and relevant a manner as possible.
I really confuse people with my choice of words, it appears, as much as any eggheaded physicist could hope to do with jargon.
Physical phenomena, being 'stuff happening on the cosmic scale, and what causes it' was the way I was using "ToE"....
Those last few lines went beyond my knowledge (save for the hydrogen ratio part), either way... so I'll assume you're 100% correct about whatever it is you're talking about...
“A meritocratic society is one in which inequalities of wealth and social position solely reflect the unequal distribution of merit or skills amongst human beings, or are based upon factors beyond human control, for example luck or chance. Such a society is socially just because individuals are judged not by their gender, the colour of their skin or their religion, but according to their talents and willingness to work, or on what Martin Luther King called 'the content of their character'. By extension, social equality is unjust because it treats unequal individuals equally.” "Political Ideologies" by Andrew Heywood (2003)
Well as matter of fact it is.
The theory of everything is "two things", namely:
Shit happens and then you die.
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Okay, mark it on the calendar - I agree with EXE.
-- I feel so much better since I stopped trying to believe.
"We are entitled to our own opinions. We're not entitled to our own facts"- Al Franken
"If death isn't sweet oblivion, I will be severely disappointed" - Ruth M.
Fair enough. Let me see if I can fill you in. But first, let me give some background on the matter for other readers.
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So, we have the ability to determine the chemical makeup of stars. Taking the sun as an example, it is approximately 75% hydrogen and 25% helium. Taken just as numbers, they are nice numbers but the problem arises that we also know the rate at which stars can convert hydrogen into helium and the fact is that there just has not been enough time since the beginning of the universe for that much helium to have formed.
The conjecture arises that shortly after the big bang, elements other than hydrogen must have formed in order for the observed abundance of helium to be reasonable. Again, fair enough but then we run into another problem. Free neutrons have a half life of just about 15 minutes, after which they decay into a proton, an electron and an electron anti-neutrino. Honestly, it is not all that hard to determine that the number of protons in the universe is consistent with there having been no significant neutron decay in the first few minutes of the universe.
Such neutrons as there are must have been captured in atomic nuclei in the critical first few minutes after the universe was cool enough for neutron to have formed in the first place.
Deep breath.
Remember that there was only a very small window of time for heavy elements to have formed and in fact, there was only enough time for element up to a nuclear mass of 5 to have formed. All other elements must have formed in some other way.
There is a huge problem here. Specifically, there are no stable configurations of nuclear mass 5. That would be either 3 protons and 2 neutrons (which would more or less instantly rip apart from electrical repulsion or 3 neutrons and two protons which would not be sufficient to prevent neutrons from entering the decay mode. The full story is rather more complex but run with that much for now.
So the big bang simply could not have formed the elements which are needed to make the universe as it exists. Yet it exists.
Here is where the anthropic principal comes into play.
Because we exist, it is necessary that there be a way for heavier nuclei to have formed. Because they cannot have formed in the few minutes after the big bang, they must have been formed in the cores of the first generation of stars.
As it happens, the astronomer who developed the possible ways that heavy elements can form in stars was Fred Hoyle. Based on the idea that it is necessary that we exist, he reasoned that something called the “triple alpha process” must be the key step that gets past nuclear mass 5. If that was true, then there should be a key property of the carbon 12 nucleus. He predicted that property and just a few months later, nuclear scientists were able to measure that property. As it happens, he almost perfectly nailed the matter down. His prediction was closer to the eventual observed property than most scientists ever get.
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In an interesting irony of science, despite this, Fred Hoyle went to his grave unable to accept the big bang theory. He was a lifelong proponent of an alternate theory called continuous creation which even during his lifetime was disproved.
However, it gets interesting that it was Fred Hoyle who gave the BBT it's name. In a radio interview, he half derisively referred to the existing but as yet unnamed theory as “This, this theory that the universe started with a big bang”. The name stuck.
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Overall, that's essentially correct, but I'll pick some nits along the way.
When the Universe's temperature was above about 1 GeV, about 1013 K, there were no hadrons, but a quark-gluon soup instead. Hadrons condensed out at around that temperature, protons and neutrons and their antiparticles and lots and lots of light mesons. But for every billion or so antiprotons and antineutrons, there was one extra ordinary proton and neutron. As the Universe expanded, it became too cold to produce proton/antiproton and neutron/antineutron pairs, so the protons and neutrons and and antiprotons and antineutrons annihilated with each other, leaving those excess ones.
At first, there were about equal numbers of protons and neutrons, because they would get converted back and forth by reactions with other particles. But those others froze out as the Universe expanded and cooled, with the least massive hadrons, pions, freezing out at about 100 MeV. Protons and neutrons still interconverted as a result of their reactions with electrons and positrons and (anti)neutrinos, but when the temperature dropped below a few MeV, neutrinos had to cross the size of the then-observable Universe before they could interact, and they effectively stopped interacting ("neutrino decoupling"
. This effectively froze the neutron/proton ratio, and after that, it would only change by nuclear reactions and free neutrons decaying.
There are two low atomic numbers that lack stable nuclei: 5 and 8. These served as barriers to Big Bang nucleosynthesis; it could not proceed much further than helium.
It's possible to obtain the primordial helium abundance by observing various galaxies, and using oxygen abundance as a proxy for stellar nucleosynthesis. Extrapolating to zero oxygen yields a sizable amount of helium, about 25% by mass.
The cores of massive stars get around that A = 8 by the triple-alpha process: two helium-4 nuclei combine to make a beryllium-8 nucleus, and before it can decay, another helium-4 nucleus collides with it, making carbon-12. Fred Hoyle noted that for the final step to proceed at reasonable speed, carbon-12 must have a resonance or excited state at some suitable energy for that, and that state was indeed observed some years later.
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Some people argue that the Universe must be designed so that this elaborate song-and-dance of a Universe history can proceed just right for us. But why bother with such a song and dance in the first place when one can poof the Universe into existence in whatever state one desires?
It must be conceded that some features of our Universe are convenient for us, like its having 3 space dimensions and 1 time dimension. More than 1 time dimension: no well-defined direction of time. More than 3 space dimensions: no stable orbits. Less than 3 space dimensions: complexity limited.
I've seen the multiverse hypothesis: that it has a lot of "bubble Universes" with different topologies and boundary conditions and the like which give it different effective laws of physics. We would thus be living in one that can allow us to come into existence, just as we live on a planet that can allow us to come into existence, with a primary and a satellite that are both convenient for us. This is natural selection can thus work on a cosmic scale, and it must be pointed out that our Universe is only borderline habitable for us.
Yeah, even if there is some validity in the idea that the likelihood of a 'random' Big Bang producing a universe capable of supporting some form of intelligent life is impossibly small, it is hardly a serious argument for 'design' by some nominally 'omnipotent' agent, since overall it seems only just marginally suitable, with an enormous amount of matter and energy deployed to achieve this.
Favorite oxymorons: Gospel Truth, Rational Supernaturalist, Business Ethics, Christian Morality
"Theology is now little more than a branch of human ignorance. Indeed, it is ignorance with wings." - Sam Harris
The path to Truth lies via careful study of reality, not the dreams of our fallible minds - me
From the sublime to the ridiculous: Science -> Philosophy -> Theology
A lot of the Universe is hidden from us, and requires technology to make apparent -- if it is accessible at all.
We see only a few thousand out of the 100+ billion stars of our Galaxy, and that's not even other stars' planets or other galaxies.
We need telescopes to resolve details of the planets, and even then, we cannot see much. Only a few stars have ever been resolved with telescopes, like Betelgeuse.
Coral reefs and reef fish are often beautiful-looking, but it was rather hard for us to get a good look at a reef before scuba technology was invented.
The Universe has a lot of microstructure that one needs specialized equipment to study, like microscopes and particle accelerators.
It also contains lots of chemical elements that are not very necessary to us, and likewise with elementary particles.
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The fundamental laws of nature feature mathematics that many people find almost impossibly arcane. If one finds algebra difficult, one won't get anywhere with the mathematical formulation of Newtonian mechanics, let alone relativity or quantum field theory.
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Nearly all of the Universe is just plain lethal to us. Even much of the Earth's surface is not very suitable for us, being too dry or too cold or too high. We can't breathe water, and we'd suffocate in a few minutes in outer space or on the surfaces of most of the Solar System's condensed objects. Even worse, we'd get roasted to a crisp inside the Sun.
The theory of anything anyone ?