String Theory Explained Simply.

[CraigS]

Originally Posted by Geoff Mc

I’d like to endorse Craig’s (#34) and Suzy’s (#1 and #17) comments. Craig’s comments are an honest summary of what non-experts do in science: we’re fans and supporters as well as sceptics. Suzy’s sheer wonder of the science (and other scientific activities described in other threads) is refreshing and inspiring. She is a model student!

For your reference to me - thank you. I am honestly trying my absolute best in this thread.
As far as your comment about Suzy - I am positive that Suzy transcends being a student. I have learnt, and continue to learn more from her every day. She lays it all on the line, and is one of the most open people I've ever encountered. Yep .. I'm a Suzy fan !

From a philosophical perspective, we need to be a little careful. For instance, saying theories don’t need evidence is wrong:

I don't think anyone's said that 'evidence' is not needed. The comment about this referred to 'proof' being required. That happens later in the process … before something becomes a scientific 'law'.

[EDIT] PS: Oops .. sorry Geoff .. you're right ..I just re-read Peter's previous post. Experimental evidence is lacking. This doesn't invalidate the theory, however. String 'theory' is falsifiable. This qualifies it formally, as scientific 'Theory'. It is beginning to make predictions. These predictions should be specific to String Theory only and not be shared by Quantum Field Theory or General Relativity to make it fully legit.

theories are based on evidence and are descriptions that attempt to explain the available evidence. The test of a theory is in its predictions, and this is where string theory has problems: its predictions are not testable, at least at the moment. That does not make it invalid, by the way.

Agreed - watch this space, though (see my post on Scientists 'testing' String Theory).

It really doesn’t matter who the individual making a contribution to science is (professional, amateur, etc), but rather what science does with their contribution. Science is a process that is self-correcting. It is not individual scientists who make progress, but rather the process of science that weeds out the incorrect ideas, no matter where they come from. Whatever remains is as close to the truth as we can get…at the moment.

Yeah .. its not perfect, though - it can be corrupted and this is very frequently done so .. by clever pseudoscientists (who I'll assert: were created by the very scientific process we're talking about here).

'Peer review' helps to keep publishing scientists, honest.

It ain't perfect but its the best we've got.

Cheers & thanks for your comments, Geoff - very cool (from my perspective)

[The_Cat (Jeremy)]

Originally Posted by Suzy

Just read those comments Craig.

It's very easy for people that don't know anything in this area to put it down. I'm sure Einstein got his fare share also. If we didn't persue the desire to understand, we wouldn't know any better. String Theory todate holds the biggest key to undertanding the universe. Einstein's general relativity theory only takes us so far. String theory hopes to bring together the four forces: gravity, electromagnetism, and the two nuclear forces (the weak and the strong). Einstein gave up trying to come up with a single unification theory. To quote his own words: "The unified field theory has been put into retirement. It is so difficult to employ mathematically that I have not been able to verify it somehow, in spite of all my efforts. This state of affairs will no doubt last many more years."

The research on this has been going on for 30 years. I doubt very much if so many scientists would dedicate so much involvement in it if it wasn't worth pursuing. We should all have an open mind when it comes to new theories, otherwise we would still believe the Earth is the centre of the universe.

To quote Einstein: "Great spirits have always encountered violent opposition from mediocre minds".

My twopence worth:

I like the above comments.

The problem with this stuff and its understanding is the directions from which it comes. Its all predicated on geometry. In some geometries parallel lines never meet and in other geometries parallel lines can intersect at a point.

Now GR works because of the properties of the space chosen and Einsteins call to fame is that he came up with a "deceptively simple" equation - his Field equation, it is actually incredibly complex set of equations. Now like all equations these need to be solved so this is where every mathematician and his dog comes in. These equations have no co-ordinate frame (you have to choose one to make life easier) so you can choose something like a star and (now for the good part) 22 pages of sums later it can be shown that we postulate black holes, event horizons etc. etc.

Now if one has enough "street cred" the university will fund an experiment to test this hypothesis - you get time on telescopes (radio and optical).

Jeremy

[CraigS]

Originally Posted by The_Cat

Now if one has enough "street cred" the university will fund an experiment to test this hypothesis - you get time on telescopes (radio and optical).

Jeremy

Yep, Jeremy .. its all part of the progress towards progress.



Cheers

[Suzy]

Geoff & Craig, wow what compliments, thank you guys.

I know everyone will have different opinions etc, but I think it's important to just keep an open mind, is all. In fact, I think it's even a good thing when people say "I don't agree with it because" ...(whatever the reason). I do have a problem when it's referred to as "it's all a heap of rubbish". The latter leaves no room for discussion. I prefer the science where it gets you thinking and asking questions, instead of the latter comment which is pointless & disruptive.

We've come a long way, as professor Kaku said recently, we have learned more in science in the last 50 years than we have ever before in the history of mankind.

[GeoffMc (Geoff)]

I have no doubt that Suzy knows more than I've seen so far. What I mean by "student" does not mean lack of knowledge. On the contrary, from my experience, the best teachers are the best students simply because they are always open to new information and knowledge, and have accumulated so much. Paradoxically, I always like to listen to quiet people since they often know more than most.

As to the connection between theory and law, it is a common error to think a law is a theory that has been verified beyond reasonable doubt. A law is a phenomenon that has been observed many times, and no contrary examples found, that it is accepted as a universal phenomenon. Examples are the law of gravity, laws of thermodynamics, etc. A theory, on the other hand, is an explanation of an observed phenomenon. Theories do not become laws, no matter how much evidence they accumulate, because they are explanations of phenomena, not the phenomena themselves.

As an example, contrary to popular belief, Newton didn't come up with a theory of gravity. In fact he said quite plainly that he didn't know what gravity was. What he did do was put forward a law of gravity (Fg = (Gm1m2)/D^2) which he found was obeyed everywhere. (Of course, Newtonian gravity has since been shown only to work on limited scales of mass and distance.) Einstein, on the other hand, put forward a theory of gravity to explain what it was. His theory made predictions that have been verified over and over again, but General Relativity will never become the "Law of General Relativity".

The frustrating thing about science is that it will never be able to reveal the ultimate truth of anything because of the problem of induction (it only takes one negative example to destroy a theory, and you can't examine all examples of a phenomenon throughout all time and space). From here it gets really philosophical. My point is there is no proof in science, never has been, never will be. Whenever I hear the phrase "scientific proof" I know the speaker doesn't really understand what science is. Actually, I'm not sure anyone does...

[CraigS]

Geoff;

Yep .. you've gotten me to re-read my definitions of scientific principles. You're right on the mark.

Interestingly, there are formal 'proofs' in mathematics, (which is clearly core 'science'). These 'proofs' are actually obtained from deductive reasoning. My understanding of this is that such 'proofs' are then used as qualifications of mathematical 'truths'. Extrapolation of these to physical sciences however, is not necessarily straightforward, (or even appropriate, for a given circumstance).

I wonder whether String Theory, being formally defined in mathematics, causes the error in understanding you mention. I have a feeling that people who see the mathematics involved in science, automatically see this as constituting 'proof' that what it is describing must also follow the same logic. This is clearly not the case, though.

I've seen both sides of this perspective in recent controversial discussions. Perhaps String Theory suffers this effect also ?

Interesting.

Cheers

[Suzy]

Originally Posted by Geoff Mc

I have no doubt that Suzy knows more than I've seen so far. What I mean by "student" does not mean lack of knowledge. On the contrary, from my experience, the best teachers are the best students simply because they are always open to new information and knowledge, and have accumulated so much. Paradoxically, I always like to listen to quiet people since they often know more than most.

Hi Geoff, I didn't take what you said as "student" in a negative way, honestly. . But what a great save anyway- you're exceptionally good at shovelling yourself out of a hole! . I'm still definitely a student trying to get my head around all this complicated stuff. Learning all the way as I plod along asking myself more and more questions. Apart from what I read, and watch, Steven, Carl and Craig have taught me loads also, on this forum. In the past, I've never been into physics nor maths, so this has turned into an interesting road for me - I'm basically trying to run before I can walk. I'm so interested in the complexities, I struggle because I have to keep going back to learn fundamentals. For instance, seeing a whole page on atom breakdowns makes my head spin, I can't retain that stuff. I'll retain basics for the time being. I have to keep telling myself I don't hold a degree and make do with what will feed my curiosity for the time being. Quantum mechanics is one very complicated area. And at times, I'm sure I'm going to be asking some really silly basic questions here, but that's the way it goes if I'm going to keep learning.

Your post was brilliant! Wow! You are so great with words, I look forward to more posts from you.

[CraigS]

A bit off topic (sorry Suzy) … here's another example of a scientific 'law':

Hubble's Law (quote from Wiki):

(1) all objects observed in deep space (interstellar space) are found to have a doppler shift observable relative velocity to the earth, and to each other. And, (2) that this doppler-shift measured velocity, of various galaxies receding from the Earth is proportional to their distance from the Earth and all other interstellar bodies.

In effect, the space-time volume of the observable universe is expanding (from a smaller past to a larger future).

Hubble's Law is the direct physical observation of this process, as it unfolds. The law was first derived from the General Relativity (GR) equations by Georges Lemaître in 1927. Edwin Hubble derived it empirically in 1929 after nearly a decade of observations. The recession velocity of the objects was inferred from their redshifts, many measured earlier by Vesto Slipher (1917) and related to velocity by him. It is considered the first observational basis for the expanding space paradigm and today serves as one of the pieces of evidence most often cited in support of the Big Bang model.

So, it started from Einstein's GR theory and it was derived from empirical observations.

It amazes me that even this masterpiece, with so much empirical evidence, and predicted by theory, is still challenged and, in some cases, completely rejected by some folk. They cannot accept that the redshift evidence implies an expanding universe.

Cheers

[Suzy]

Great post! What a terrific example!

[NeilW]

http://imgs.xkcd.com/comics/string_theory.png


Just about sums it up...

[cwjohn (Chris)]

Beware of Wikipedia. It can be misleading and is often plain wrong. Most universities in examining students will now mark you down should you quote wikipedia (as I have found out to my great cost on several occasions).

So in this case the space time volume of the non-observable universe is expanding, but in fact the light cone of the observable universe is contracting assuming you adopt the standard model of cosmology.

Application of Hubbles so called law to the universe is not simple. Many misconceptions were spelled out by Tamara Davis and Charlie Lineweaver at http://msowww.anu.edu.au/~charley/pa...neweaver04.pdf

Standard redshift theory is not only rejected by some "folk", but also by many cosmologists, although it is fair to say that the majority accept the implication in greater or lesser degree. At base however, this is simply a theory which is "believed" as there is no way we can travel to other galaxies to test variance in physical parameters of the influence on redshift measurements from other effects. The main plank on which cosmologists base their assumptions is simply consistency of measurement over several disiplines together with occams razor i.e. the simples solution is usually the best.

Personally I find the current cosmological model compelling but should another arise which negates standard redshift assumptions I would neither be shocked or surprised.

[avandonk]

Use wikipedia by all means but always track down the original peer reviewed papers and quote them. Once you have one you should have the lot as they can be traced just like DNA to the seminal paper.

Science is NOT about answers! It is all about good questions.

Even two year olds know this as they keep asking questions for every answer you give!

Bert

[CraigS]

Hmm;

Very interesting, Chris.

I have no major issues with what you say, as both my post #48 and your post #51, both state valid points of view.

Your comments about Wiki: Shades of grey. Your warning about Wikipedia is generalised and whilst I think we all know to be cautious about quoting from Wiki for certain topics, from the perspective of emphasing the validity of Hubble’s Law as scientific Law, and for the purposes of promoting discussion in an Amateur Forum/General Chat topic, it would seem sufficient. Had this discussion been raised in the Science forum … fair enough … we’d have an ‘interesting’ time of it.

I am a little disturbed by your words: “Application of Hubble’s so called law.”
The paper you provided is a most interesting read. Much empirical supporting data has been accumulated since it was published, (2003), and thus it is probably fair to say that nowadays, the majority of mainstream scientists go about their business with the metric expansion of space (as supported by Hubble’s Law), as a given. It is also probably fair to interpret this as their direct acceptance of the body of supporting evidence.

I was once challenged “how much evidence does it take for you to accept something ?”.

It really got me thinking.

The issues the paper discusses, seem to deal with misconceptions surrounding interpretations of Hubble’s Law, but are not directed at the law itself.

Hubble’s Law still meets the criteria of scientific classification as a “Law”, which was the main intent of my post.

Perhaps we could find more formal wording of Hubble’s Law.

Cheers & Thanks for your input.

[cwjohn (Chris)]

A "law" is merely a formulaic approach to an idealised form of a theory. e.g the laws of gravity, ohms law, hubbles law. In many cases the law can be disproved in real world applications. This is analogous in many ways to societal laws which lawyers tend to make of mockery of in many cases.

The paper I cited was not intended to dispute Hubbles Law, but rather to indicate the nature of the universe when special and general relativity are applied. Nor was the paper meant to dispute the standard treatment of redshift as it certainly does not do this..

I am unaware of any empirical data since the paper was published that changes the points made in the paper. In fact I would argue that very little of any significance has happened in cosmology in the last decade. Merely book-keeping in many ways.

As to your question "How much evidence does it take for you to accept something" that will entirely depend on the person. On the basis of the evidence before me I "believe" that there is a strong possibility that the cosmological model is sound, but I would not be ambitious enough to enshrine it as a law. I can test the merits of Ohms Law and the laws of gravity here and now and many times over. Thus I can give it a high confidence level and say that with 90% confidence this law represents the idealised situation, and it can be suitably modified to allow for the real world. There is no way I can test Hubbles Law or the cosmological equation other than by induction.

Accordingly, I would not seek to criticise those (as you do) that hold either no view or a contrary view on the standard model of cosmology this to include religious views, given the unsure ground upon which we stand. You are in good company though given that luminaries like Hawking advocate the same approach, but then I suspect his interest is in selling books.

[CraigS]

Originally Posted by cwjohn

Accordingly, I would not seek to criticise those (as you do) that hold either no view or a contrary view on the standard model of cosmology this to include religious views, given the unsure ground upon which we stand. You are in good company though given that luminaries like Hawking advocate the same approach, but then I suspect his interest is in selling books.

Chris;

I do not recall ever criticising anyone for their beliefs, one way or the other.

As a matter of fact, I usually go out of my way to make the point that anyone can believe whatever they want.

I'm a campaigner for not holding any cosmological beliefs too close to heart, also.

Science isn't about finding the truth. This simply isn't relevant to science.

I think we're both in vigorous agreement about this.

All I said was that it 'amazes' me.

In this lower-rigour forum, I trusted that I would be granted a chance to express some feelings on this matter with the broader IIS community.

Cheers