Multiple universes: Nothing more than philosophising?

[richard9678]

Why do astronomers talk about multiple universes, that is philosophising - isn't it?

 

[DelcrossA]

I'm taking your meaning to be "is it pointless" to which the answer is of course not. Predictions don't make themselves and so to progress our understanding, various models need to be fleshed out and made falsifiable, which is only done by researching them. Moreover, I find it ridiculous how negative of a connotation philosophy has amongst some scientists. Without philosophy of science/physics/mathematics, you are just plugging in numbers into equations with zero context and without any real attempts to obtain an understanding.

 

[Quds Akbar]

It may explain Dark Matter, it may explain why Dark energy's strength is the way it is, it presents ideas and solutions that many find satisfying.

 

[phinds]

Why do astronomers talk about multiple universes, that is philosophising - isn't it?

Basically, yes. Although there are some very serious scientists (Sean Carroll comes to mind) who believe in the multiverse there is absolutely zero evidence to support it and the multiverse theories make no falsifiable predictions. Popper argues that this clearly means such theories are not science but Carroll says we need to rethink the whole business of falsifiability as a test on theories. I admire Carroll but I hope science does not go down that road.

 

[sk1105]

Carroll says we need to rethink the whole business of falsifiability as a test on theories. I admire Carroll but I hope science does not go down that road.

I agree. It would be a travesty and a huge hit to the credibility of science if we abandoned one of its cornerstones to make some theories more attractive without doing any actual observations.

Bringing this back to the original question, who is to say that the multiverse theory won't one day be falsifiable with some not-yet-invented piece of equipment? The ancient Greeks and Indians had ideas about atoms, but could never in their wildest dreams have imagined the experiments that would one day prove their existence.

 

[phinds]

Well, so far there aren't any predictions that are falsifiable with ANY equipment. The multiverse, as far as I know, is forever causally removed from out universe.

If/when multiverse theories include falsifiable predictions that becomes a different story.

 

[Chronos]

There have been, and will continue to be efforts to devise observational tests of multiverse theories. I haven't seen any yet that appear capable of falsifying the multiverse. It's unclear, at least to me, if that's even possible in principle. Until the need for a multiverse can be empirically demonstrated, I feel it's little more than an exercise in imagination. Science is not just about the possible [that's what math is for], it's about what is necessary.

 

[richard9678]

I'd actually say, that if someone believes that billions of years ago there was a big bang, it's a matter of well, common sense there would be multiple universes.

But, myself, I doubt whether there was a big bang. Gut feeling. :-)

 

[richard9678]

I find it strange that one time and perhaps not long ago intelligent people would say maybe there are other planets around stars with life. Common sense the universe is teeming with planets and life. IMHO.

 

[yamex5]

Why do astronomers talk about multiple universes, that is philosophising - isn't it?

Yes, the strongest reason I've heard is that there are too many variables with just the precise value to make it likely that our universe could exist (but not impossible!). The multiverse hypothesis says that many of the possible universes have popped into existence, and so our 'improbable' universe becomes probable because it is just one of many, equally probable universes that exists.

 

[Drakkith]

I'd actually say, that if someone believes that billions of years ago there was a big bang, it's a matter of well, common sense there would be multiple universes.

The big bang was not an event, it is a process describing the evolution of the universe from its high density and temperature state to the current low density and low temperature state. In that sense I see no reason to believe in other universes.

 

[Drakkith]

Yes, the strongest reason I've heard is that there are too many variables with just the precise value to make it likely that our universe could exist (but not impossible!).

This assumes that the laws in our universe just happen to be as they are because of pure chance. It's possible they simply couldn't be any other way.

 

[Chronos]

I view that as one of the worst possible explanations for the values of natural constants. It's pretty obvious, at least to me, the laws of physics are not fine tuned for our existence, we are fine tuned for existence compatible with the laws of physics.

 

[OCR]

Moreover, I find it ridiculous how negative of a connotation philosophy has amongst some scientists.

I agree, and it's a damn shame!...

 

[Chronos]

I think much of the philosophy backlash in the science community is driven by leaps of logic that often prove flawed, and sometimes patently naive after the facts become known. I agree this is regrettable to some extent. Many of histories finest scientists had strong philosophical leanings that led them to spectacular discoveries - e.g., Einstein. On the other hand, intuition, however reasonable, must still be vetted scientifically. Science without philosophy is like the three blind men describing an elephant. It's a necessary evil if we aspire to stitch the quilt together. Academia still awards the title Doctor of Philosophy to qualified seamstresses.

 

[metacristi]

Why do astronomers talk about multiple universes, that is philosophising - isn't it?

If we were to follow rigidly the falsificationist account of what is science then it's metaphysics. But then we should include in the same category superstring theory and so on. Personally I think things are much more complex.

There is an interesting article in Scientific American Special Edition 2014 'Secrets of the Universe' ('Does the Multiverse really exist?', you can also read it here: http://www.relativitycalculator.com/articles/multiverse_exist_george_ellis/page_38.html ).

Personally I agree with the main conclusion of the author, indeed currently there is no conclusive evidence for the multiverse (which to establish the concept as part of accepted scientific knowledge) but at the same time I disagree with the philosophical background involved in his argument.

I'm much more sympathetic with Sean Carroll here, having moved long ago beyond the Popperian philosophy of Science, see What scientific idea is ready for retirement? (http://edge.org/response-detail/25322); falsifiability may not need to be retired but it is definitely just one of the methodologies used by science, being not the infallible criterion to demarcate science from non science thought by some Popperians.

In short the Multiverse theory is a scientific research program (as is the string theory etc) but the level of justification for it at the moment (involving both theoretical and evidential aspects) is way too weak to talk even of provisional scientific knowledge (as a side note in my view all scientific knowledge, indeed knowledge in general, should be considered provisional and possibly corrigible in non trivial ways, even the best established knowledge should not be exempted from possibly being on the 'wrong branch' or a 'special case' in a deeper reality).

Yet the future can be full of surprises, the case for the Multiverse can still become very well as compelling (via Rationality) for physicists as it is the inflationary scenario now, applying rigidly the criterion of falsifiability can only harm fully legitimate directions of research.

 

[sk1105]

Yet the future can be full of surprises, the case for the Multiverse can still become very well as compelling (via Rationality) for physicists as it is the inflationary scenario now, applying rigidly the criterion of falsifiability can only harm fully legitimate directions of research

This is sort of what I was trying to get at with my earlier post, although I'm not sure I agree that the criterion of falsifiability per se can only harm research. I still think falsifiability is what separates the scientific method from other modes of thinking, but, as you and I both suggested, just because a theory is not falsifiable right now does not mean we should summarily consign it to the dustbin along with aether, geocentrism and the like. A theory can still exist and have compelling mathematical arguments behind it, but testable predictions should still be what promote (or not, of course) a hypothesis to the realm of accepted scientific knowledge.

 

[Orien Rigney]

Knowing absolutely nothing of physics, I depend on the intellect of others to row me across the lake; so to speak. When some hypotheticals such as strings theory or multiverses are hashed over, where does the theories come from? Is there ways of calculating their possibility, or physical proof that they can or do exist? I ask this only because, if they are just ideas, we all have a few to offer. Let me put one of Dr. Penrose's out there that hypothesizes a cyclic universe..

I do like the theory but there is little I can offer other than ideas. But listening to the stutter steps he makes in explaining the theory baffles me. Very possibly there has been enough theory and calculus from Penrose and Hawking to go deeper into the possibility that such a universe may exist. With what is being found out about dark matter etc. and the increase in exansion velocity, many of the answers may be right in front of us. Can anyone help in looking into such a possibility further?

 

[Drakkith]

If we were to follow rigidly the falsificationist account of what is science then it's metaphysics.

Not necessarily. I've seen at least one multiverse theory that makes observable claims. I think it's important to make a distinction between what isn't observable in principle and what isn't observable because we just haven't seen it yet.

 

[metacristi]

Knowing absolutely nothing of physics, I depend on the intellect of others to row me across the lake; so to speak. When some hypotheticals such as strings theory or multiverses are hashed over, where does the theories come from? Is there ways of calculating their possibility, or physical proof that they can or do exist? I ask this only because, if they are just ideas, we all have a few to offer. Let me put one of Dr. Penrose's out there that hypothesizes a cyclic universe..

I do like the theory but there is little I can offer other than ideas. But listening to the stutter steps he makes in explaining the theory baffles me. Very possibly there has been enough theory and calculus from Penrose and Hawking to go deeper into the possibility that such a universe may exist. With what is being found out about dark matter etc. and the increase in exansion velocity, many of the answers may be right in front of us. Can anyone help in looking into such a possibility further?

Theories are 'free creations of the mind', to paraphrase Einstein, and it does not have any importance where they come from (dreams, sudden inspiration, religious beliefs, pondering on the consequences of accepted theories and so on are equally valid sources). What really count in science is the confirmation part, the theories should be testable, with some of the predictions separating them from the other existing hypotheses. If the theories (+ their auxiliary assumptions in reality) survive the test of reality and are (much) more confirmed than the alternatives then they usually become part of scientific knowledge, the 'normal paradigm' of the day.

In the case of Penrose I suppose that his 'conversion' was triggered also by the existing proposals regarding the cyclical Universe (apart from the theoretical considerations he presented). Now in what regard the confirmation context I don't think we can advance any objective prior probability of such hypotheses being true and as far as I know no experiment indicates them as 'the winner' (they are falsifiable). Yet although at least some variants are still definitely viable (also in light of the fact that the results of BICEP 2 study was put in a different perspective by Planck observations) they are by no means the first choice program deserving to be pursued further at this time (not ultimately because they have lower coherence with the accepted body of scientific knowledge).

To conclude anyone can propose hypotheses but only those which pass the experimental test can succeed to become science (although I really doubt that the scientific community will always pay attention to very good ideas coming from outsiders :) ).

 

[Drakkith]

(although I really doubt that the scientific community will always pay attention to very good ideas coming from outsiders :) ).

That's because really good ideas don't come from 'outsiders'. At least not when it comes to new theories about physical laws. Besides, ideas are cheap. They're a dime a dozen. Everyone has ideas. It's the ability to follow through with an idea and see where it ends up that really counts. In addition to that, it's important to realize that when it comes to physics, all the 'easy' ideas have been thought of already and found wanting. This isn't the 1800's anymore.

I'd also like to say that I don't like the term 'outsider'. That implies that it's 'us' vs 'them'. It's not. The skills and methods science uses to advance human knowledge are simply refined versions of the skills and methods everyone uses every day. Some people just don't realize that.

 

[Vanadium 50]

there is absolutely zero evidence to support it and the multiverse theories make no falsifiable predictions.

I am not by any stretch of the imagination a multiverse fan, but I think you're being a bit unfair. The multiverse theories try answer two questions:

1. Why did inflation start and why did it stop?
2. Why do we see the sorts of apparent fine-tunings of various parameters?

I don't think there are any alternatives to either of these, although there are ideas that attempt to partially answer #2 - for instance, the small Higgs mass can be explained by supersymmetry. I would instead say that the evidence is entirely circumstantial.

I am aware of one-sided multiverse tests: for example, if there were an early universe collision between multiverse bubbles, it would leave evidence in the polarization of the CMB. If there were a collision between multiverse bubbles, that would mean they exist. If there were no collision, that doesn't mean they don't.

 

[Chronos]

As long as multiverse theory resists validation via empirical evidence, it's explanatory power is an illusion, IMO.

 

[Orien Rigney]

It may explain Dark Matter, it may explain why Dark energy's strength is the way it is, it presents ideas and solutions that many find satisfying.

Not necessarily. I've seen at least one multiverse theory that makes observable claims. I think it's important to make a distinction between what isn't observable in principle and what isn't observable because we just haven't seen it yet.

What are the observable claims?

 

[Orien Rigney]

Orien Rigneys replies: I agree! Coming to the forum I instinctively felt such a blocking atmosphere almost immediately. While I'm not a Physicist or Mathematician, I have read just about everything I can muster on astronomy and our universe. If an idea of mine or one I have read should arouse an innterest in someone who knows physics and calculus, I would feel extremely gratified.
All my life I have learned one thing to be an absolute fact, Quote: It's the doer and not the philosopher that eventually gets the job done. Unquote

 

[Orien Rigney]

Theories are 'free creations of the mind', to paraphrase Einstein, and it does not have any importance where they come from (dreams, sudden inspiration, religious beliefs, pondering on the consequences of accepted theories and so on are equally valid sources). What really count in science is the confirmation part, the theories should be testable, with some of the predictions separating them from the other existing hypotheses. If the theories (+ their auxiliary assumptions in reality) survive the test of reality and are (much) more confirmed than the alternatives then they usually become part of scientific knowledge, the 'normal paradigm' of the day.

In the case of Penrose I suppose that his 'conversion' was triggered also by the existing proposals regarding the cyclical Universe (apart from the theoretical considerations he presented). Now in what regard the confirmation context I don't think we can advance any objective prior probability of such hypotheses being true and as far as I know no experiment indicates them as 'the winner' (they are falsifiable). Yet although at least some variants are still definitely viable (also in light of the fact that the results of BICEP 2 study was put in a different perspective by Planck observations) they are by no means the first choice program deserving to be pursued further at this time (not ultimately because they have lower coherence with the accepted body of scientific knowledge).

To conclude anyone can propose hypotheses but only those which pass the experimental test can succeed to become science (although I really doubt that the scientific community will always pay attention to very good ideas coming from outsiders :) ).

Isn't that being a bit snobbish? If someone came to me and stated that my house was on fire, my first question wouldn't be: "Are you a Fireman"?

 

[sk1105]

Isn't that being a bit snobbish?

I think perhaps you are confounding the term 'science' to mean the group of people who all share a following of scientific ideas no more or less valid than any other beliefs. This is a common theme often encountered in discussions concerning homeopathy, vaccine dangers and other pseudoscience (for illustrative purposes only - I am not for one minute suggesting that you subscribe to those arguments). The term 'science' refers only to the process of developing models that explain our surroundings, testing them in the real world and then either confirming, refining or even discarding them altogether. As @Drakkith pointed out earlier, you don't have to be a 'scientist' to engage in this process.

 

[AgentSmith]

Why do astronomers talk about multiple universes, that is philosophising - isn't it?

Some cosmologists, such as Andre Linde, have linked inflation to the idea of multiverses. While not convincing, its compelling.

 

[magneticnorth]

Theorizing , hypothesizing and philosophizing ...are all valid roads to science . If Occam's Razor is to be considered as a credible /usable postulate . Looking at things from that angle , String Theory , and Multiverse, can fall into the category of philosophizing . When testability and falsifiability or at least predictability ,become available , they then become Science . Does that sound logical ?

 

[Quds Akbar]

What are the observable claims?

Dark Matter might be the gravitational effects of a universe hovering right above us. Dark energy exists in the exact numbers it should to support life, a little bit less and the universe would collapse on itself, a little bit more and the universe would be expanding too rapidly. But with the existence of an infinite multiverse with huge amounts of multiverses, a multiverse with those properties would be normal, you would expect to find a universe like this.

 

[phinds]

Dark Matter could be the gravitational effects of a universe hovering right above us.

Uh ... how do you "hover right above" something in all directions and predominantly in galactic halos? This really doesn't make any sense.

 

[Quds Akbar]

Uh ... how do you "hover right above" something in all directions and predominantly in galactic halos? This really doesn't make any sense.

The universe could be above us, I think this wording would explain it.
"let's say that our universe is a sheet of paper. We live our entire life on this sheet of paper, but directly above us there could be a parallel universe, hovering right over us, perhaps inches, centimeters away and objects in this parallel universe would be invisible. Light travels beneath the universe, so we never see this other galaxy. But gravity, gravity goes between universes because gravity is nothing but the bending of space, so if the space between two sheets of paper is bent slightly gravity then moves across. This other galaxy in another universe would be invisible, yet it would have mass. That's exactly what dark matter is. Dark matter is massive—it has gravity—but it's invisible." (Michio Kaku,2011)

 

[phinds]

The universe could be above us, I think this wording would explain it.
"let's say that our universe is a sheet of paper. We live our entire life on this sheet of paper, but directly above us there could be a parallel universe, hovering right over us, perhaps inches, centimeters away and objects in this parallel universe would be invisible. Light travels beneath the universe, so we never see this other galaxy. But gravity, gravity goes between universes because gravity is nothing but the bending of space, so if the space between two sheets of paper is bent slightly gravity then moves across. This other galaxy in another universe would be invisible, yet it would have mass. That's exactly what dark matter is. Dark matter is massive—it has gravity—but it's invisible." (Michio Kaku,2011)

(1) Kaku is a gadfly who is not to be taken seriously.
(2) this does not explain why dark matter is mostly in galactic haloes not does it even come close to explaining the bullet cluster, just to name one problem with it.

 

[Orien Rigney]

Theorizing , hypothesizing and philosophizing ...are all valid roads to science . If Occam's Razor is to be considered as a credible /usable postulate . Looking at things from that angle , String Theory , and Multiverse, can fall into the category of philosophizing . When testability and falsifiability or at least predictability ,become available , they then become Science . Does that sound logical ?

Thanks! But somehow I always seem to put my foot in my mouth at the wrong angle and time. Since all fields of science need new ideas constantly, I see nothing wrong with offering my thoughts on a subject. That doesn't mean that I have an answer or solution, only questions that, if the right person gets hold of them, may have an an answer just waiting to pop out. Thanks again.

 

[Quds Akbar]

(2) this does not explain why dark matter is mostly in galactic haloes not does it even come close to explaining the bullet cluster, just to name one problem with it.

Yes, I do not aid this parallel universe idea, you bring up a very good point, but others do believe in it, that is why people believe in a multiverse, that is the point of this thread. If you go to my second reply, I used the term might be.

 

[phinds]

Yes, I do not aid this parallel universe idea, you bring up a very good point, but others do believe in it, that is why people believe in multiverses, that is the point of this thread. If you go to my second reply, I used the term might be.

Fair enough

 

[Orien Rigney]

The universe could be above us, I think this wording would explain it.
"let's say that our universe is a sheet of paper. We live our entire life on this sheet of paper, but directly above us there could be a parallel universe, hovering right over us, perhaps inches, centimeters away and objects in this parallel universe would be invisible. Light travels beneath the universe, so we never see this other galaxy. But gravity, gravity goes between universes because gravity is nothing but the bending of space, so if the space between two sheets of paper is bent slightly gravity then moves across. This other galaxy in another universe would be invisible, yet it would have mass. That's exactly what dark matter is. Dark matter is massive—it has gravity—but it's invisible." (Michio Kaku,2011)

Scanning down and seeing this topic made me want to jump in with my ignorance and both feet, if I may? The sheet of paper thing? If we are part of a multi-universe system as some think, I find it difficult to understand the concept do to the fact that from earth, we can see in all directions over 13 billion light years. Also, if the sheet of paper theory is correct, at an estimated speed of over 2 million miles per hour and ever increasing in velocity, our universe is bound to encounter another of its multi-verse neighbors sooner or later.

 

[phinds]

..., at an estimated speed of over 2 million miles per hour and ever increasing in velocity, our universe ...

Huh? Where did you get that number? What do you think it represents?

 

[Quds Akbar]

Scanning down and seeing this topic made me want to jump in with my ignorance and both feet, if I may? The sheet of paper thing? If we are part of a multi-universe system as some think, I find it difficult to understand the concept do to the fact that from earth, we can see in all directions over 13 billion light years. Also, if the sheet of paper theory is correct, at an estimated speed of over 2 million miles per hour and ever increasing in velocity, our universe is bound to encounter another of its multi-verse neighbors sooner or later.

Think of it as a universe above us.

 

[Chronos]

The notion of gravity influencing our universe by leaking from 'nearby' parallel universes emerged from string theory. The hypothesis goes like this - parallel universes reside on branes [short for membranes], which are manifolds embedded in a higher dimension called the bulk. Branes conform to the holographic principle in the sense of being lower dimension objects embedded in a higher dimension, the bulk. At least part of the motivation for this idea was to explain why gravity is so weak compared to the other fundamental force of nature. Despite its noble intent, brane theory has never achieved wild popularity because it has not resulted in predictions that cannot be reproduced by simpler theories; and we all know the bias science has for simple explanations - i.e., Occam's Razor.

 

[Orien Rigney]

Huh? Where did you get that number? What do you think it represents?

Got to admit, the 2 milion mph requires several annotations to come up with that figure, but it was one without par secs or metric units.
Look at this link.

Huh? Where did you get that number? What do you think it represents?

 

[phinds]

Got to admit, the 2 milion mph requires several annotations to come up with that figure, but it was one without par secs or metric units.

Numbers like that are not particularly meaningful and certainly have nothing to do with the expansion rate of the universe which is WAY more significant than how fast we are moving relative to other objects or the CMB and even that concept is not meaningful in terms of a multiverse or encountering another brane.

 

[Czcibor]

I am not by any stretch of the imagination a multiverse fan, but I think you're being a bit unfair. The multiverse theories try answer two questions:

1. Why did inflation start and why did it stop?
2. Why do we see the sorts of apparent fine-tunings of various parameters?

I don't think there are any alternatives to either of these, although there are ideas that attempt to partially answer #2 - for instance, the small Higgs mass can be explained by supersymmetry. I would instead say that the evidence is entirely circumstantial.

I am aware of one-sided multiverse tests: for example, if there were an early universe collision between multiverse bubbles, it would leave evidence in the polarization of the CMB. If there were a collision between multiverse bubbles, that would mean they exist. If there were no collision, that doesn't mean they don't.

For question 2. I think that many religious people would give you a quite consistent answer that so far is as empirically testable as multiverse hypothesis. ;)

I think about a bit different approach - why not just say that multiverse hypothesis is just one of possible interpretation of quantum theory? Because I think that with so abstract concepts there is a problem that to what extend that you can get an ability to calculate or predict something, but without actually understanding what is going on.

 

[rootone]

For question 2, I believe the anthropic principle is as good an explanation as is multiple universes .
Observations of the physical Universe must be compatible with the conscious and sapient life that observes it.
If things were otherwise we could not exist and observations could not be made.

 

[Chronos]

The anthropic principle is useless, save for ruling out the impossible. Obviously, any observation that infers existence of the observer is impossible implies either the observation, or underlying basis for that inference is incorrect.

 

[rootone]

I do agree that the anthropic principle, while it must be true, it is essentially a philosophical position that can't be used to draw scientific conclusions.
I think the multiple universes proposal also is a philosophical position that can't be used to draw scientific conclusions..
If anything it is inferior as a philosophical proposal since unlike the anthropic principal it is not self evidently true.

 

[Ken G]

To me, the issue is not so much "is there a multiverse," or even, "is the existence of a multiverse a scientifically testable model," because it is probably too soon to make much of a judgement on either of those issues (it might be hard for a long time, it's hard to say). The interesting issue that we can address right now is, "what is a scientific explanation." When someone says the multiverse "explains" why the constants are finely tuned, or "explains" why inflation stopped at just the right moment to generate a universe like ours, what does that mean? Surely it must mean a lot more than "it gives us a sense of understanding to hold that there is a multiverse", because as has been pointed out, it also gives many people a sense of understanding to say "god did it," but we can all agree that isn't a scientific explanation. Yet when people like Carroll and Weinberg talk about multiverses, I don't see them gaining much more than that same basic sense of understanding, that feeling like it makes sense somehow-- but that isn't science, not by itself. So falsifiability has come up, and the need to make predictions-- we can agree that is important to be able to call something a scientific explanation. But I'd say the most important thing Popper said about science is that it must make "risky predictions", which basically means, it has to be possible that some idea is wrong, it cannot be so flexible that it can accommodate any result. This is what bothers me about the multiverse idea-- the very thing that defines it makes it questionable as science, it's extreme flexibility. So what I want to know is, does the multiverse concept "explain" anything in our particular universe that it could not also "explain" in any other completely different universe, but just wouldn't seem important or necessary for?

Let me put the question this way. Imagine there "really is" a multiverse, whatever that means. So most of the universes are generic, and have no need for the multiverse concept because they don't exhibit fine tuning. Is that not somewhat ironic-- it is a theory that only the rare universe would even need to invoke in the first place. Imagine a situation like that applied to fortunes in a fortune cookie-- most people find them to be very generic and not saying anything particularly tailored to their own lives, yet every once in awhile someone gets one that seems perfectly suited to some situation they are in. Would it be valid for those few who see some import in the fortune to regard fortunes as predictive because they work so well in those special cases? Do we ever let the special cases do the scientific explanations?