Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Why we think there's a Multiverse, not just our Universe

scienceblogs.com

Post reply on HN
Print view View original

41–50 of 57 posts

Re: Why we think there's a Multiverse, not just our Universe

#41

Post by gyardley »

bad_user wrote: post #35
powertower wrote: post #13

Earlier quoted context omitted.

I envision a world where, due to technology and science, everyone stops aging after 25. A clock will be constantly visible on your forearm and time will be the only commodity in the world, in which you'll get paid and make payments in. After the age of 25, you'll get 1 to 75 years of "time" deposited in your account. The clock on your arm will decrement by default as time passes, and increase/decrease as you earn/spe…

I envision a world where ... You could try being a little more original: http://www.imdb.com/title/tt1637688/

'In Time' itself could try being a little more original - the main premise probably comes from either a great late-80s short called 'The Price of Life' (http://vimeo.com/16265933) or a 1970s Lee Falk story, 'Time is Money'.

Re: Why we think there's a Multiverse, not just our Universe

#42

Post by nu23 »

xenophanes wrote: post #12
anakanemison wrote: post #9

Earlier quoted context omitted.

I think it's more unfortunate than irrational. I'd like to think I'm open to changing them--my priors started out (a couple of decades ago) pretty terrible. The process of how to do it well in response to arguments without experimental results is the challenging part.

Bayesianism is in the empiricist tradition where it's focussed on how to update ideas in response to evidence, but it doesn't actually provide guidance for how to deal with non-empirical ideas that can't be judged by evidence. This (empiricism) has driven philosophers to things like positivism (where they declare everything non-empirical to be worthless or even meaningless). It's a problematic tradition. The problems…

About the example of grass that you talk about, I think that amounts to a criticism not of empiricism but direct hypothesis checking. We have built up a model of human body and grass which tells us that it would be harmful. Now this background model has been subject to empirical checks at lots of times and has evolved in presence of new empirical discoveries. (Though of course, the model has not been derived axiomatically from empirical data).

Almost nothing in science is justified by direct checks. Think of any clinical trial or say, the LHC experiments. There are so many implicitly assumed background theories about how the instruments respond to their stimuli. Some of these instruments are based on principles which were discovered only in this century. So scientists from previous times wouldn't accept the way the results are derived unless they are shown the results derived from previous experiments justifying the way the instruments work. For example, the atomic hypothesis was controversial till 1900 or so. How would one even interpret LHC electron beams if one one doesn't believe in the atomic hypothesis? A useful analogy here, is minesweeper - a new opened square, whose information, via a very long chain can tell us if there is a mine on a far away square.

Re: Why we think there's a Multiverse, not just our Universe

#43

Post by xenophanes »

nu23 wrote: post #42
xenophanes wrote: post #12

Earlier quoted context omitted.

Bayesianism is in the empiricist tradition where it's focussed on how to update ideas in response to evidence, but it doesn't actually provide guidance for how to deal with non-empirical ideas that can't be judged by evidence. This (empiricism) has driven philosophers to things like positivism (where they declare everything non-empirical to be worthless or even meaningless). It's a problematic tradition. The problems…

About the example of grass that you talk about, I think that amounts to a criticism not of empiricism but direct hypothesis checking. We have built up a model of human body and grass which tells us that it would be harmful. Now this background model has been subject to empirical checks at lots of times and has evolved in presence of new empirical discoveries. (Though of course, the model has not been derived axiomati…

Can you give a statement of what you mean by "empiricism" that you wish to defend?

I agree with some of what you say, but I'm not sure what you're trying to vindicate.

Bear in mind that one can construct infinitely many theories logically consistent with every piece of evidence or empirical check done in the past, and which predict that the grass cure for the cold will work. These theories will consist of various disjointed assertions in a rather arbitrary and ad hoc manner. The problem with these theories is that they are terrible as explanations -- they are bad philosophically -- but they are not empirically refuted.

Re: Why we think there's a Multiverse, not just our Universe

#44

Post by redwood »

sendos wrote: post #37

Isn't this like having a function that explains very well data that is within an observable range, and then stating with confidence that that function also applies to data in a range that is unobservable to you? Yes, that function may hold outside your observable space, but it may not. We can't simply state as fact the predictions that come from assuming that this function applies outside our observable space.

Spot on, and even much of what is 'observable' here is not even close to understood. Inflation and dark energy/matter are both concepts that have been built to explain observation but which are themselves not yet explained at least not with much consensus.

Re: Why we think there's a Multiverse, not just our Universe

#45

Post by Confusion »

borism wrote: post #22
jaequery wrote: post #21

Let's get the facts straight. Believing in a multiverse is no different than believing in heaven/hell.

* for a similar enough definition of heaven, hell and multiverse. Have you read the article?

He may very well have. There is not a shred of experimental evidence for the multiverse. In fact, experimental evidence is not even possible. That places it firmly in the pantheon of metaphysics.

Now it could be an unescapable conclusion from an otherwise very successful theory with many experimental verifications, but unfortunately the article neglects to mention that there are many alternative interpretations and theories that can equally well explain 'how it all started' and still result in inflation and all associated theories.

That the multiverse theory successfully appeals to the imagination is the main pillar of its succes.

It's a shame he is being downvoted for succinctly stating a plain truth.

Re: Why we think there's a Multiverse, not just our Universe

#46

Post by Confusion »

As the only criticism on this article has been downvoted strongly, I feel compelled to repeat my explanation of that criticism (that believing in the multiverse is like believing in heaven or hell) at a higher level, in the hopes that people will be somewhat more critical of what esteemed scientists are peddling as truth:

There is not a shred of experimental evidence for the multiverse. In fact, experimental evidence is not even possible. That places it firmly in the pantheon of metaphysics.

That there is a multiverse could be an unescapable conclusion from an otherwise very successful theory, with many experimental verifications, but that isn't the case. The article neglects to mention that there are many alternative interpretations and theories that can equally well explain 'how it all started' and still result in inflation and all associated 'best' theories for the experimental observations of the universe. This article is all unwarranted extrapolation (back to the beginning of time and before).

The main pillar of the success of the multiverse theory is that it successfully appeals to the imagination. The main reason that it is being promoted is because the great physicists promoting the idea do not realize they are not as great philosophers as they are physicists.

Re: Why we think there's a Multiverse, not just our Universe

#47

Post by [deleted] »

xenophanes wrote: post #43
nu23 wrote: post #42

Earlier quoted context omitted.

About the example of grass that you talk about, I think that amounts to a criticism not of empiricism but direct hypothesis checking. We have built up a model of human body and grass which tells us that it would be harmful. Now this background model has been subject to empirical checks at lots of times and has evolved in presence of new empirical discoveries. (Though of course, the model has not been derived axiomati…

Can you give a statement of what you mean by "empiricism" that you wish to defend? I agree with some of what you say, but I'm not sure what you're trying to vindicate. Bear in mind that one can construct infinitely many theories logically consistent with every piece of evidence or empirical check done in the past, and which predict that the grass cure for the cold will work. These theories will consist of various dis…

[deleted]

Re: Why we think there's a Multiverse, not just our Universe

#48

Post by [deleted] »

xenophanes wrote: post #43
nu23 wrote: post #42

Earlier quoted context omitted.

About the example of grass that you talk about, I think that amounts to a criticism not of empiricism but direct hypothesis checking. We have built up a model of human body and grass which tells us that it would be harmful. Now this background model has been subject to empirical checks at lots of times and has evolved in presence of new empirical discoveries. (Though of course, the model has not been derived axiomati…

Can you give a statement of what you mean by "empiricism" that you wish to defend? I agree with some of what you say, but I'm not sure what you're trying to vindicate. Bear in mind that one can construct infinitely many theories logically consistent with every piece of evidence or empirical check done in the past, and which predict that the grass cure for the cold will work. These theories will consist of various dis…

[deleted]

Re: Why we think there's a Multiverse, not just our Universe

#49

Post by Umofomia »

Confusion wrote: post #46

As the only criticism on this article has been downvoted strongly, I feel compelled to repeat my explanation of that criticism (that believing in the multiverse is like believing in heaven or hell) at a higher level, in the hopes that people will be somewhat more critical of what esteemed scientists are peddling as truth: There is not a shred of experimental evidence for the multiverse. In fact, experimental evidence…

The author responds to this point in one of the comments; I quote:

this is -- and I make no pretensions otherwise -- theoretical physics. It's not airy-fairy pie-in-the-sky speculation, but it also isn't proven the way you would prove that a * b = b * a. You may want to read this recent guest essay (http://scienceblogs.com/startswithabang/2011/10/guest_essay_...) that does a wonderful job of explaining, with some brilliant metaphors, what this sort of theory is (and isn't).

Re: Why we think there's a Multiverse, not just our Universe

#50

Post by nu23 »

xenophanes wrote: post #43
nu23 wrote: post #42

Earlier quoted context omitted.

About the example of grass that you talk about, I think that amounts to a criticism not of empiricism but direct hypothesis checking. We have built up a model of human body and grass which tells us that it would be harmful. Now this background model has been subject to empirical checks at lots of times and has evolved in presence of new empirical discoveries. (Though of course, the model has not been derived axiomati…

Can you give a statement of what you mean by "empiricism" that you wish to defend? I agree with some of what you say, but I'm not sure what you're trying to vindicate. Bear in mind that one can construct infinitely many theories logically consistent with every piece of evidence or empirical check done in the past, and which predict that the grass cure for the cold will work. These theories will consist of various dis…

My goal was not to defend pure empiricism - that justifications for knowledge can come only from sense data. I just wanted to emphasize that, in your example, when we chose a good explanation instead of a bad one, the goodness of the explanation has a large empirical component.I am guessing that you agree with this but would focus on the non-empirical component. One non-empirical component of its goodness would be the complexity of its specification, the Kolmogorov complexity for instance.
Post reply on HN