1.) "Life as we know it" is an extremely important phrase. Ask a biologist what life is, and she will probably say something about cells and DNA. It is possible for other self-replicating combinations of molecules to exist, but not on Earth, because the Cell/DNA model has become so effective at wiping the competition out. It's actually really hard to come to a solid definition of what "life" is, but if you make it sufficiently broad, I suspect you could find life even in some universes where the fundamental constants differ significantly from ours.
2.) We have no idea what determines the fundamental constants. You cannot talk about the "odds" of having a universe like ours until you know the probability distributions for each of the fundamental constants. Look at the H2O on Earth, and you will find that a significant portion of it occurs at 0C and 100C. Of course that is not a coincidence - water often exists at those temperatures because energy is spent on converting state, not on altering temperature. It's an equilibrium point. So likewise, it's POSSIBLE that the fundamental constants (of multiple universes, if they exist) interact in ways that cause them to arrive at equilibrium points. One really fascinating theory promoting this idea (and any theory is as good as the next, since we have very little empirical evidence available to us) is Lee Smolin's argument that the singularities within blackholes are themselves universe phases. Thus, a kind of "natural selection" of black holes occurs, which leads to more and more universes with fundamental constants ideal for producing black holes (and thus close to the constants necessary for life).
3.) The anthropic principle is just way too convenient, and I fear it de-motivates scientists from looking deeper into issues that really need explaining. Roger Penrose argues that there is a surprising lack of parsimony on behalf of whatever forces (spiritual or natural) brought about our universe. While our universe appears to have inflated from an initial region with a phase-space-volume of 10^(10^123), it would have been more than sufficient to create a life-supporting universe (several! in fact) from a region with only a phase-space-volume of 10^(10^117). Additionally, Penrose points out that the odds of creating an exact duplicate of our solar system from the random coming together of gas and radiation (no Darwinian evolution necessary!) is only 1 in 10^(10^60). (Penrose calls it "utter chicken feed" compared to the odds of the Big Bang producing ANY universe of our size). So even when you invoke the anthropic principle, the question still remains - why is our (life-supporting) universe so large and so old, when we could have done with so much less?
The anthropic principle is just way too convenient, and I fear it de-motivates scientists from looking deeper into issues that really need explaining.
This I must take issue with. The anthropic principle is what drove the Renaissance. It's what motivated people like Sir Isaac Newton to better understand the universe, they believed that this was the way to get closer to God. The anthropic principle is responsible for the single biggest leap in science in the history of mankind. Saying "God created it" doesn't excuse anyone from anything; you still need to work on it, in fact the good Christian has no excuse not to.
The anthropic principle did not drive the Renaissance. The scientific revolution within the Renaissance was driven by a rediscovery of Greek/Arabic knowledge, the focus on empirical evidence that came with the invention of the scientific method, and the (yet-to-be-formalized) desire to apply Occam's razor to every explanation.
The anthropic principle is dual to Creationism. The Creationist says, "It is because God made it so." The scientist says, "It is because it necessarily must be so." Neither philosophy, by itself, leads to deeper understanding.
indeed. the article seems to be asking a false question - "just how did we get so lucky!?!?!" which seems ridiculous, and as you point out, presumes that a universe that produces us is more optimal than one that doesn't.
If gravity were slightly more powerful, the consequences would be nearly as grave. A beefed-up gravitational force would compress stars more tightly, making them smaller, hotter, and denser. Rather than surviving for billions of years, stars would burn through their fuel in a few million years, sputtering out long before life had a chance to evolve.
This is wrong, with slightly more gravity smaller stars would burn hotter but there is a wide range of stars that can last for 5 billion years. Now if was 100 times as strong they might have a point but there is about an order of magnitude to play around with.
But would we still be able to get the elements we need for life? We are partly made of leftovers from supernovas, and so is our sun. It takes more than just a energy source to create life - you have to have something other than hydrogen to work with.
Assuming everything else was the same and gravity was 5x as strong then a star around the size of the sun would go super nova in a short time period. (Granted it would take a lot of time to really model this.)
There is some support for Jupitor producing a little fusion with it's current mass. If you increase gravity it becomes smaller until it's heat balances out the force of gravity which increases the amount of fusion taking place.
PS: Less massive stars have a higher surface area to volume ratio. This reduces their temerature which reduces their fuel usage. But once they run out of fuel the same type of interesting things are going to happen.
The multiverse is my favorite scientific hypothesis. It just seems right. It's always been cool to think about the boundary conditions of our universe (how big? how long? how much?). But one among many? That's utterly baffling and exciting.
Unfortunately, without evidence, it's an argument of faith, like any other.
I like the simulation hypothesis. I love how it "explains" some of the constants we see & quantum physics.
I don't see how belief in "the multiverse" is any different than belief in a god or the simulation hypothesis. They all have zero evidence and can't be tested. The obvious question in all three is: what was there before? So they all have the same problems.
The simulation hypothesis actually becomes more likely, though still not proven, if we get to the point where we can run our own simulated universe.
We might also demonstrate that we were in a simulation if we found an exploit to take over the simulator's webcam (assuming the simulator didn't patch and revert). Universal buffer overflow!
Baffling and exciting in the same way that the set of reals is larger than the set of integers even though both are infinite. Also, Zeno's Paradox is my favorite.
That something can't be falsified right now does not make it unscientific. As long as something can, in principle, be falsified, it's a valid scientific hypothesis - but perhaps not a useful one.
For the record, I haven't read the article in question closely enough to know if what's being proposed can even be falsified in principle.
True, neither multiverse theory nor a singleverse theory can be proven. But both are scientific in the sense that they (sort of) predict the structure of our universe. The question then becomes how to select one of the theories. Occams razor provides little help, since both theories are similarly complex, so one possible way to select a theory is to use Bayes rule. I'll sketch this reasoning:
The laws of physics are governed by equations which output only a probability distribution P(x) for various quantities (positions of particles, the values of certain fundamental constants).
(Note: I really don't understand any of this stuff well, so if someone (Dani?) with better knowledge can correct me or clarify, I'd love to see it.)
In a single-universe theory (SUT), one postulates that a particular x is selected, at random, relative to P(x) dx. In this theory, it is highly unlikely that the universe can support life (or at least life like us). In a multiverse theory (MUT), one postulates that all x are selected in parallel. In this case, our particular x will be chosen; the fact that we live in a good universe is not luck, merely natural selection. So the probability we exist is close to 1.
Both these theories are more or less equally "simple" (think Kolmogorov complexity), so let us assume they each "occur" with the same or similar "probability" (i.e., p(SUT)=p(MUT)=1/2). Then we use Bayes rule:
So multiverse theory is more "probable" than single universe theory. This remains true even if you wildly alter the complexity of competing theories, e.g. p(SUT)/p(MUT) = 1e6.
It's true, we can never falsify SUT or MUT relative to each other. But we can make educated guesses as to which one is more "probable". And yes, this is pretty sketchy, hence my use of scare quotes everywhere. But it's the best we can do right now.
I guess for lack of scientific rigour? Theories aren't scientific because of the maths, they're scientific because of the approach, which involves creating testable hypotheses that can be determined to be right or wrong. The reason why these two are not scientific theories is not because no one can come up with some maths to support them, but because there is no way to observe them.
I did a physics degree. I studied atomic physics and quantum mechanics. We briefly brushed on the multi/single universe, but largely that was not examined in too much detail in the physics cursus. People who were doing Physics & Philosophy, however, got plenty of detail in their course. My point being: this is philosophy, not science.
[edit: my turn to wonder why I am being downmodded, lol]
Both theories are testable. They both (sort of) successfully predict the structure of the universe, up to some parameter choices (e.g., fine structure constant). There are ways to falsify both theories simultaneously since they make nearly the same predictions, we just don't have ways to falsify one but not the other.
The question is 'absent plausible experiments, how do we choose between single and multiple universes?' And that is done using occams razor; the 'simpler' or 'more probable' theory is chosen, for a somewhat (but not completely) arbitrary definition of 'simpler'.
Occams razor is a philosophical point, as is (to some extent) your definition of 'simpler'. I thought I was careful to highlight those points.
I was merely trying to explain the reasoning multiverse theory, but in a less vague manner than the article did (I trust most of HN to know Bayes rule).
Incidentally, this thread is bringing out behavior which is weird for HN. Someone downmodded your comment, also for reasons which are completely inscrutable to me.
Don't worry. The writer just (unfortunately) phrased it that way for a lay audience. It is in no way a reaction or an alternative to anything to do with creationism.
If I recall correctly, the "universe" is a concept meant to encompass all that exists. How then can there be multiple universes? Wouldn't the set of all universes itself exist within the universe?
It seems more likely to me that "universe" here is being defined as "what we can observe", in which case these multiverses are simply the unobservable part of our universe.
I guess that's part of my objection, really. The use of the word "universe" implies that there is only one of them, as the prefix "uni-" in Latin means "one".
I don't think the idea that the universe is finely tuned for life(not necessarily life as we know it) is that unreasonable. I dislike the idea of a creator for the obvious reason that you run into an infinite regression. What created the creator, etc... So how do we get around this? Could it be possible that the universe created itself? In the void, there are infinite possibilities. If there existed a pattern which sustained itself, somehow propagated itself in perpetuity, would it then exist? Then the fact that the universe seems finely tuned for life would be an obvious consequence. Something like us would be needed to tend the light, we would be a necessary component of this pattern. Anyway, I like it better than the idea of a huge number of "dead" universes, although I doubt we'll ever know the Truth of the matter.
The solution is too complex. Complex things don't survive, because complexity tends to decay. The universe has to be based of a very simple concept - but our minds, which are developed for earth-style biology has not yet landed on that concept.
To some extent, actually, yes. Here's a way of doing it.
Let us say that a hyper-advanced civilization has the ability, through simulations or otherwise, of calculating the odds of life arising in a universe with given initial conditions and fundamental constants (to some rough accuracy). They can test billions of possible initial states, including our own, and use that to see whether we lie in a very probable location in phase space or an improbable one. If the location is probable, it strongly supports the multiverse theory.
If the location is improbable, the theory is likely false. For example, if the average probability of life arising in a given universe in some chunk of phase space that includes ours is 40%, and ours is in a subsection of that phase space with a 30% probability, the multiverse theory is not falsified. If ours is in a subsection of that phase space with a 0.000001% probability (far lower than average), it suggests that multiverse is unlikely, because our existence seems to be in violation of pure chance.
The same method can be used to falsify evolution. Test billions of simulations of the Earth's development of life, and see where our species falls statistically. If we're in a probable area of the phase space (phase space of possible sentient creatures to evolve), our understanding of evolution is likely correct, and if we're in a very improbable area (many many standard deviations away from the most likely), our understanding must be flawed somewhere.
Exactly how? Or are you just going to respond with a useless one-liner rather than actually explain your objection?
Statistical analysis of probabilities is a method of analyzing the odds of a theory's validity. If a theory requires that reality be extremely improbable, that theory is highly unlikely. And when there's absolutely nothing else you can do, its the only option other than blind faith.
I'll repeat this again:
If a theory requires that reality be extremely improbable, that theory is highly unlikely.
The entire point of the Anthropic Principle is to attempt to answer this question by stating that if reality was not improbable as such, we wouldn't exist to ask that question.
Do you object to this concept? How is this concept a violation of the scientific method?
In it, you will find the "essential elements" of the scientific method:
* Characterizations (observations, definitions, and measurements of the subject of inquiry)
* Hypotheses (theoretical, hypothetical explanations of observations and measurements of the subject)
* Predictions (reasoning including logical deduction from the hypothesis or theory)
* Experiments (tests of all of the above)
The last two elements are missing from your approach, and it is hence unscientific.
Please note that the anthropic principle is not a scientific theory, it is a wild guess at why things might be what they are.
If a theory requires that reality be extremely improbable, that theory is highly unlikely.
This is a very wild conjecture with no substantiating evidence. It is wholly equal to blind faith, and in no way superior to it.
Please note that the anthropic principle is not a scientific theory, it is a wild guess at why things might be what they are.
It is wholly equal to blind faith, and in no way superior to it.
So, by your logic, the anthropic principle is wholly equal to blind faith? Sure, its not strictly science, and more of a logical argument than a scientific experiment (much like my original post), but really?Equal to blind faith?
If you are that deluded, I'm not even going to bother arguing this. This is pointless. Go get yourself a source a bit better than Wikipedia and educate yourself.
Wikipedia has become a fairly good reference for these sorts of basic principles.
In terms of intellectual "worth thinking about"-ness, the anthropic principle may be more worthwhile than blind faith, but in terms of science, it is equally worthless.
You need to revise your understanding of how science works, or else you'll only continue to blunder around.
>Critics say it doesn’t even qualify as a scientific theory because the existence of other universes cannot be proved or disproved. Advocates argue that, like it or not, the multiverse may well be the only viable nonreligious explanation for what is often called the “fine-tuning problem”—the baffling observation that the laws of the universe seem custom-tailored to favor the emergence of life.
Its amusing that some are so adamant against the unprovable concept of a creator that they go to such lengths as believing in something else equally unprovable.
I like the multiverse concept. Its cool. Maybe a creator created this ;)
Quantum computing as a field arose from David Deutsch's desire to build an experiment which could test the multiverse interpretation of quantum mechanics. The idea was that if it were able to find a solution to a problem which was not tractable in one universe, then it would support the notion of a multiverse.
I think there's a line between unscientific and scientific conjecture. No scientist worth their salt considers the multiverse interpretation more than a conjecture, which seems fair game. It's fine for scientists to go grasping at straws, since I believe that's fundamental to the creative processes that result in new theories, but it's important to note where that's happening and where theory is unfolding.
there's a lot of talk of probabilities in the article but it seems hackneyed
the universe has almost countless variables that can result in near-infinite states, but there is a 100% chance that one state must emerge (i.e. a 100% chance that reality exists), and it isn't clear if the alternative scenarios they describe (particles of different masses, stronger gravitational impact on stellar mass) are more probable than our own. the scientists see our state as optimal because we live in it, but why couldn't our state be suboptimal? maybe there was a potential state (never realized) that resulted in us all being omnipotent. there seems to be a bias from the researchers regarding our own state, but they haven't demonstrated that its any more or less likely than any other outcome
1.) "Life as we know it" is an extremely important phrase. Ask a biologist what life is, and she will probably say something about cells and DNA. It is possible for other self-replicating combinations of molecules to exist, but not on Earth, because the Cell/DNA model has become so effective at wiping the competition out. It's actually really hard to come to a solid definition of what "life" is, but if you make it sufficiently broad, I suspect you could find life even in some universes where the fundamental constants differ significantly from ours.
2.) We have no idea what determines the fundamental constants. You cannot talk about the "odds" of having a universe like ours until you know the probability distributions for each of the fundamental constants. Look at the H2O on Earth, and you will find that a significant portion of it occurs at 0C and 100C. Of course that is not a coincidence - water often exists at those temperatures because energy is spent on converting state, not on altering temperature. It's an equilibrium point. So likewise, it's POSSIBLE that the fundamental constants (of multiple universes, if they exist) interact in ways that cause them to arrive at equilibrium points. One really fascinating theory promoting this idea (and any theory is as good as the next, since we have very little empirical evidence available to us) is Lee Smolin's argument that the singularities within blackholes are themselves universe phases. Thus, a kind of "natural selection" of black holes occurs, which leads to more and more universes with fundamental constants ideal for producing black holes (and thus close to the constants necessary for life).
3.) The anthropic principle is just way too convenient, and I fear it de-motivates scientists from looking deeper into issues that really need explaining. Roger Penrose argues that there is a surprising lack of parsimony on behalf of whatever forces (spiritual or natural) brought about our universe. While our universe appears to have inflated from an initial region with a phase-space-volume of 10^(10^123), it would have been more than sufficient to create a life-supporting universe (several! in fact) from a region with only a phase-space-volume of 10^(10^117). Additionally, Penrose points out that the odds of creating an exact duplicate of our solar system from the random coming together of gas and radiation (no Darwinian evolution necessary!) is only 1 in 10^(10^60). (Penrose calls it "utter chicken feed" compared to the odds of the Big Bang producing ANY universe of our size). So even when you invoke the anthropic principle, the question still remains - why is our (life-supporting) universe so large and so old, when we could have done with so much less?