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Author Topic:   Logic and Empiricism
Grizz
Member (Idle past 5471 days)
Posts: 318
Joined: 06-08-2007


Message 31 of 55 (404902)
06-10-2007 1:03 PM
Reply to: Message 29 by Straggler
06-10-2007 12:34 PM


Re: Predictions
When we use reason to deduce conclusions that have not yet been empirically detected we call these predictions.
However without the ability to then empirically test these predictions against nature I don't see how we can possibly establish them as facts.
This is, in my opinion, the key difference between true science and all the various forms of pseudo science that exist out there including creationism in it's various guises.
Regarding my comments related to String Theory in my preceeding post:
The existence of compact dimensions and multiverses is predicted by the theory yet by neccesity forever beyond our ability to measure, observe, or experience. If one were to experimentally establish the existence of Strings does this establish the existence of the compact dimensions and multiverses predicted by the theory? If yes the result of reasoning alone can arrive at the existence of a phenomenon forever beyond our ability to experience or measure.
Edited by Grizz, : No reason given.

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Straggler
Member
Posts: 10333
From: London England
Joined: 09-30-2006


Message 32 of 55 (404903)
06-10-2007 1:14 PM
Reply to: Message 30 by Grizz
06-10-2007 12:55 PM


It all depends exactly how string theory were validated through experimentation and exactly how fundamental to the workings of the theory the whole multiverse idea really is.
To take a better known example - Quantum theory and the collapse of the wave function - There are many that would say that this is strong evidence for the many worlds theory in some guise or other. The mathematics implies it. Wave particle duality and interference patterns can be explained in terms of it etc. etc. However even with this relatively (as compared to that for string theory ideas) strong evidence I would suggest that calling the many worlds interpretation of quantum theory as an indisputable 'fact' rather than a realistic interpretation would be stretching things for all but it's most ardent advocates.
Predictions that require a particular interpretation to be true and then verification of these predictions are needed before the word 'fact' can be bandied around.
Even then there will be those that dispute the interpretation so a body of evidence based on verification, prediction and corroboration with other established theories will be required before it can be held up as a theory to match evolution, big bang theory etc. etc. as effectively established facts.
Such is the way of science.
Edited by Straggler, : No reason given.

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 Message 30 by Grizz, posted 06-10-2007 12:55 PM Grizz has replied

Replies to this message:
 Message 33 by Grizz, posted 06-10-2007 1:25 PM Straggler has replied

  
Grizz
Member (Idle past 5471 days)
Posts: 318
Joined: 06-08-2007


Message 33 of 55 (404904)
06-10-2007 1:25 PM
Reply to: Message 32 by Straggler
06-10-2007 1:14 PM


The brane dimensions are required to make the mathematics consistent. They are absolutely critical to the theory. In practice we could only detect the existence of Strings themselves or other phenomenon that support the existence of Strings. We don't detect theories or parts of theories - we verify theories by verifying experimentally what they predict or dismiss - in this case the existence of Strings. We would never be able to experimentally measure or experience the brane dimensions by the very nature of what they are.
Therefore we could only say 2 things about the ontological status of branes:
- They are simply a convinient mathematical tool wihtin the theory and do no exist in reality.
- They exist in reality and their existence is established by reason and not by emperical measurement or observation.
If one takes the position that the existence of Strings neccesitates the existence of Branes and Multiverses then one has arrived at a phenomenon that by their very nature is forever beyond our ability to measure or experience yet has a causal influence on the universe in which we exist. One would then be forced to conclude there are phenomeon that are forever beond our ability to experience or measure yet in fact exist in reality.
Edited by Grizz, : No reason given.
Edited by Grizz, : No reason given.

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 Message 35 by JustinC, posted 06-10-2007 3:48 PM Grizz has replied

  
Straggler
Member
Posts: 10333
From: London England
Joined: 09-30-2006


Message 34 of 55 (404910)
06-10-2007 1:56 PM
Reply to: Message 33 by Grizz
06-10-2007 1:25 PM


On that basis I don't think the argument as to the validity of the 2 possible conclusions could be definitively claimed either way.
However should another theory (hypothetical - I have no such theory in mind), completely seperate to string theory, but equally reliant on branes to justify it's mathematics come along and be empirically verified independently of string theory - then the reality of branes as more than a mathematical construct would be independently corroborated and effectievly verified in it's own right.
But I do think it would take something like that to settle the argument one way or the other.
Without it the existence of branes cannot be considered scientific 'fact'

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JustinC
Member (Idle past 4843 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 35 of 55 (404918)
06-10-2007 3:48 PM
Reply to: Message 33 by Grizz
06-10-2007 1:25 PM


quote:
If one takes the position that the existence of Strings neccesitates the existence of Branes and Multiverses then one has arrived at a phenomenon that by their very nature is forever beyond our ability to measure or experience yet has a causal influence on the universe in which we exist. One would then be forced to conclude there are phenomeon that are forever beond our ability to experience or measure yet in fact exist in reality.
I don't quite understand this. Science takes ideas and tries to expose them to observation by deducing predictions from a theories framework. If the Brane theory has a causal influence on our universe and makes predictions about our directly observable universe, then it can be verified by experience.
In this way, Brane theory's validity is determined by experience.

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Grizz
Member (Idle past 5471 days)
Posts: 318
Joined: 06-08-2007


Message 36 of 55 (404924)
06-10-2007 4:42 PM
Reply to: Message 35 by JustinC
06-10-2007 3:48 PM


Perhaps I should of stated that more succinctly. This is similar to the emergence of the idea of the idea of Black Holes that arrose out of the mathematics present in the Theory of General Relativity. For a while it was hotly debated whether such entities in fact existed as part of physical reality. When General Relativity appeared on the scene Singularities(infinities) have never been shown to be present in nature. The mathematics, however implied just that - a singularity. Simply because the mathematics implied their existence does not neccesarily mean such singularities actually exist in nature. The astronomical community set out to try to find emperical evidence for their existence. Without such evidence the notion would simply be relegated to speculation. The last I read on the subject there appears to be a substantial body of astronomical observations that directly supports their presence in physical reality.
With String Theory the situation is different. As theorists themselves readily admit the branes are compactified dimensions forever removed from our ability to detect. How would you conduct an experiment to detect their existence? At the present moment nobody has any idea. Verifying the theory emperically would only establish that the theory is capable of describing some aspect of physical reality. It would not emperically demonstrate that branes are real just as the emperical proof for General Relativity did not demonstrate that Black Holes are physically real.
The ideas of Multiverses is even more difficult. There are a large number of solutions to the equations, each of which is speculated to correpond to a seperate universe of it's own. Each would have it's owns constants and resulting laws. There have been many interesting accounts of this in the pop science literature on the book shelves. These multiverses - should they exist - would forever be removed from any causal connection with one another. They would therefore never be able to be established as scientific fact as they could never be emperically observed.
Edited by Grizz, : No reason given.
Edited by Grizz, : No reason given.

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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 37 of 55 (404929)
06-10-2007 5:20 PM
Reply to: Message 36 by Grizz
06-10-2007 4:42 PM


With String Theory the situation is different. As theorists themselves readily admit the branes are compactified dimensions forever removed from our ability to detect. How would you conduct an experiment to detect their existence? At the present moment nobody has any idea.
[quibble]
Check Lisa Randall's Warped Passages. There are plenty of predictions on branes and additional dimensions that will be tested in the next few years at LHC. If additional dimensions exist we will find them (maybe). From these we can strengthen hypotheses on branes leading to testable predictions there.
[/quibble]
If something has an effect on this universe, given time, we will find the evidence. If something has no effect on this universe then, for all practical purposes, it does not exist.

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Replies to this message:
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 Message 40 by Straggler, posted 06-10-2007 5:53 PM AZPaul3 has replied

  
Straggler
Member
Posts: 10333
From: London England
Joined: 09-30-2006


Message 38 of 55 (404930)
06-10-2007 5:33 PM
Reply to: Message 36 by Grizz
06-10-2007 4:42 PM


I am still not sure what your point is?
In the case of either black holes or branes the mathematical interpretation used to predict their existence is exactly that - a mathematical interpretation on which predictions can be made.
Only when empirical evidence is found can they become established scientific facts. Empirical evidence can, and often does, include detailed predictions of unknown phenomemnon that are based on the logical consequences of the theory in question i.e. branes in this case.
Branes themselves do not have to be detected directly for empirical evidence to be used to verify or refute their existence.
We did not have to witness the BB first hand to establish it as a scientific fact. Detailed predictions of CMB eventually nailed that one.
This was true of black holes, for which direct empirical evidence does now exist, as you have already stated and it remains true of branes.
If it really is the case that these branes are totally undetectable and that no predictive experiment can be done to indirectly verify or refute their existence then they will remain useful mathematical constructs that may or may not be describing a something prfound about the nature of reality.
You seem to want a definite yes or no to a question to which the only viable scientific answer is that 'without more empirical evidence we cannot say either way for certain'.
So what is your point regards branes and the OP regarding logic and faith etc???

This message is a reply to:
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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 39 of 55 (404932)
06-10-2007 5:38 PM
Reply to: Message 37 by AZPaul3
06-10-2007 5:20 PM


{OT comments}
Check Lisa Randall's Warped Passages. There are plenty of predictions on branes ...
Amazon.com
Price: $18.45 - not bad
Sabine Hossenfelder: Backreaction: Lisa's Warped Passages
quote:
Lisa's book is titled "Warped Passages" and explains about everything you need to know about high energy physics and physics beyond the standard model.
I don't see any point in giving you another detailed review on the book's content, you might want to check out those at amazon.com instead. Let me just say that the book provides you with a fairly self-consistent introduction into the idea of extra dimensions, covering general relativity, quantum mechanics (even quantum field theory) the standard model of particle physics, and string theory.
It successfully captures the excitement and the beauty, but it makes also clear what we know - and what we don't. It is well written, entertaining and very structured.
For a popular science book, it is very precise in the statements and it covers a lot of ground. If you are not familiar with the subject, you probably will have to think about it for a while. On the other hand, this makes the book also interesting for those with an education in physics.
Sounds like my kind of book and a good read.
Thanks. {/OT comments}
Edited by RAZD, : the price is (now) right

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Straggler
Member
Posts: 10333
From: London England
Joined: 09-30-2006


Message 40 of 55 (404936)
06-10-2007 5:53 PM
Reply to: Message 37 by AZPaul3
06-10-2007 5:20 PM


Beyond Branes
Predictions based on branes are exactly what I was missing from my last post to Griz so thanks for pointing me in the direction of those.
I am not sure where exactly he is going with the branes argument specifically but there may be an interesting point in all of this.
Lets take a hypothetical situation. Lets imagine that a ToE has been found. Quantum gravity explained, fundamental particles predicted and experimentally verified as a result of the new ToE. Holy grail in place and all is well with the world.
Lets imagine that the mathematics of our ToE suggests the existence of numerous empirically undetectable universes. This same mathematics is used for all sorts of practical applications and accurate predictive results in our own universe which establish it truly as a theory of everything.
Fundamental to this mathematics is the existence of universes that have no practical effect on our universe.
As you say
If something has no effect on this universe then, for all practical purposes, it does not exist.
In this sceanrio
Do we trust the math and it's empirical results in our limited sphere of experience to conclude that the other universes must exist?
Or do we deny their existence as fact on the grounds of lack of empirical evidence?
I think this is what Griz is getting at with the Branes argument.

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 Message 42 by Grizz, posted 06-10-2007 6:47 PM Straggler has not replied
 Message 43 by Grizz, posted 06-10-2007 6:50 PM Straggler has replied
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AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 41 of 55 (404943)
06-10-2007 6:37 PM
Reply to: Message 40 by Straggler
06-10-2007 5:53 PM


Re: Beyond Branes
Lets imagine that the mathematics of our ToE suggests the existence of numerous empirically undetectable universes. This same mathematics is used for all sorts of practical applications and accurate predictive results in our own universe which establish it truly as a theory of everything.
Fundamental to this mathematics is the existence of universes that have no practical effect on our universe.
Sounds like this hypothetical ToE has a lot going for it. I would doubt then if the theory would include something for which there was no effect in our universe. If such a ToE showed that the multiverse was probable then it would also predict a testable effect. We are talking a strong predictive theory here not a hypothesis. I cannot conceive that it would include in its mathematical model something which had, by definition, no effect to model.
But let's play the game.
If the theory predicted something that had not, and could not have, any discernable effect on our universe then the math is predicting something that cannot be said to exist. It wouldn't matter whether this thing was real or not. For us, it has no effect, it means nothing, and therefore might as well not exist.
Now if you're thinking that maybe based on the knowledge of this non-effective thing we develop further hypotheses that may have some practical discernable effect or use to us, then this would belie the premise that the hidden non-discernable thing was actually hidden and non-discernable. It could be tested by way of these new hypotheses because of their effect in our universe.
But to answer the question specifically, if by some strange twist of math the ToE modeled something for which there could not possibly be a model then there is a hole in this beautiful and consistent theory somewhere.
Edited by AZPaul3, : The usual typo suspects.

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Grizz
Member (Idle past 5471 days)
Posts: 318
Joined: 06-08-2007


Message 42 of 55 (404947)
06-10-2007 6:47 PM
Reply to: Message 40 by Straggler
06-10-2007 5:53 PM


Re: Beyond Branes
Delete please. I hit the update button twice. Sorry.
Edited by Grizz, : No reason given.
Edited by Grizz, : No reason given.

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Grizz
Member (Idle past 5471 days)
Posts: 318
Joined: 06-08-2007


Message 43 of 55 (404948)
06-10-2007 6:50 PM
Reply to: Message 40 by Straggler
06-10-2007 5:53 PM


Re: Beyond Branes
I am not advocating a position or trying to take a position - I was just trying to get a discussion going that might cary over into the main topic of this forum. And yes Stragg - Ultimately I was asking how far is one willing to go with reason alone? What place does reason have in determining truth or value within scientific inquiry?
I studied Physics and Math as an undergrad then went on to the History and Philosophy of Science in grad school. I am currently working towards my doctorate in this field.
My study in physics was fascinating but I always found myself gravitating more towards the questions posed within the context of philosophy. I was always getting in trouble asking questions that irritated professors -'Are electrical fields real or just usefull mathematical tools to describe reality?'. Ask this question and you often get a disbelieving stare as if you just asked if Bigfoot was real. I was determined to go into grad school and continue my study in Physics but at the last minute learned of a top notch program in The History and Philosophy of Science. I was enthralled.
Scientists often dismiss the questions posed by philosophy as irelevant to the task at hand but on the contrary I believe it offers much. Most scientists rarely stop to ask why and how they do what they do on a fundamental level. The History and Philosophy of science is in itself a very complex and rich subject that has much to offer to the future of the scientific enterpise. Unfortunately it is grossly overlooked and ignored by most scientists.
On a side note my academic interest in the field is the role process and emergent properties have in nature. In our current ontological view of physical reality process is subservient to substance - it does not share in the workings of nature but is relegated to byproduct. I believe this is one of the reasons that we have yet failed to reach a consensus on an adequate interpretation of Quantum Mechanics or the nature of Consciousness and it's possible existence as an emergent property of the organism. In my view process shares equal ontological status with substance as the driving mechanism of change in nature. I do not subscribe to the notion that there exist fundamental entities that can be seperated from their environment and given autonomy. For instance in a bubble chamber a scientist is not observing a particle - the scientist is observing the interaction of the particle with the bubble chamber. It is the end result of the Quantum process itself that is being observed.
Edited by Grizz, : No reason given.
Edited by Grizz, : No reason given.
Edited by Grizz, : No reason given.

This message is a reply to:
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Replies to this message:
 Message 45 by Straggler, posted 06-11-2007 12:48 PM Grizz has replied
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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 44 of 55 (404950)
06-10-2007 6:59 PM
Reply to: Message 40 by Straggler
06-10-2007 5:53 PM


Re: Beyond Branes multiversed
Fundamental to this mathematics is the existence of universes that have no practical effect on our universe.
It seems to me that there must be at least two universes under this theory as they are caused by collision of two branes (or are we dealing with the location of collision only, and doesn't that then mean more dimensions in our universe OR fewer in the uber-universe?)
You could easily have just a single mirror universe in the other brane for an instance of what you are suggesting with your Grand Unified Theory (GUT rather than ToE "THEORY OF EVERYTHING" as Theory of Evolution = ToE normal use on this forum. Had me confused for a minute).
Enjoy.

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This message is a reply to:
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Straggler
Member
Posts: 10333
From: London England
Joined: 09-30-2006


Message 45 of 55 (405121)
06-11-2007 12:48 PM
Reply to: Message 43 by Grizz
06-10-2007 6:50 PM


Re: Beyond Branes
I too am a physics/maths undergrad who got happily sidetracked by the philosophy of science courses (all seems a very long time ago alas).
I agree that questioning the nature of reality beyond the 'that which works' mentality is interesting and worthwhile even if often frustrating and fruitless.
So given that Nator has answered the question to some degree as to how far he would take reason alone in the search for truth - how would you relate all of this back to the OP?
It seems that most of those with a scientific bent, including myself, see the deductions of reason alone as useful and potentially fruitful areas for prediction and further enquiry but are broadly sceptical of calling anything that is not ultimately backed up by empirical evidence of some sort, scientific 'fact'.

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