Superstrings / Gravity / Dark Energy

[hazelm]

In the book that I have mentioned before - "The Origin of the Universe" by John D. Barrow -  on page 58, there is a diagram of how the four forces developed - or how we think they developed.  Keep in mind that this book was published in 1994 and that is taken into consideration.  The diagram is drawn much as what we see when we look at a connection of plumbing pipes connected with L or U joints.

 

Going back as far as we can, we start with one "pipe".  The first branching off is a joint drawn as dotted lines to indicate speculation.  This joint is labeled "superstrings?".  It connects to what seems to be the first force that branched:  Gravity.

 

After stressing that the author did call all this speculation and declared that a lot of research will be necessary before anything accurate is known,  I get to my questions.  Does anyone know?  Has Superstring theory been shown to be either connected or not connected to Gravity?  I knew about the String theory but had never seen it related to Gravity.  I did some searching - mostly at Wiki - and found nothing more.

 

Now, quite by coincidence, there appears this at Science Daily:  https://www.sciencedaily.com/releases/2018/10/181009102431.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily%2Ftop_news%2Ftop_science+%28ScienceDaily%3A+Top+Science+News%29

 

Suddenly we are talking about String theory and Dark Energy  (Einstein's Cosmologial Constant, according to one comment I read).  So, is Dark Energy related to Gravity?  All this is developing into an interesting story.  I would appreciate anything anyone can add.  Or, any suggested reading.

 

Thank you.

[exchemist]

In the book that I have mentioned before - "The Origin of the Universe" by John D. Barrow -  on page 58, there is a diagram of how the four forces developed - or how we think they developed.  Keep in mind that this book was published in 1994 and that is taken into consideration.  The diagram is drawn much as what we see when we look at a connection of plumbing pipes connected with L or U joints.

 

Going back as far as we can, we start with one "pipe".  The first branching off is a joint drawn as dotted lines to indicate speculation.  This joint is labeled "superstrings?".  It connects to what seems to be the first force that branched:  Gravity.

 

After stressing that the author did call all this speculation and declared that a lot of research will be necessary before anything accurate is known,  I get to my questions.  Does anyone know?  Has Superstring theory been shown to be either connected or not connected to Gravity?  I knew about the String theory but had never seen it related to Gravity.  I did some searching - mostly at Wiki - and found nothing more.

 

Now, quite by coincidence, there appears this at Science Daily:  https://www.sciencedaily.com/releases/2018/10/181009102431.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily%2Ftop_news%2Ftop_science+%28ScienceDaily%3A+Top+Science+News%29

 

Suddenly we are talking about String theory and Dark Energy  (Einstein's Cosmologial Constant, according to one comment I read).  So, is Dark Energy related to Gravity?  All this is developing into an interesting story.  I would appreciate anything anyone can add.  Or, any suggested reading.

 

Thank you.

Thanks for this Hazel.

 

I know too little about it to make any recommendations but I am very pleased to see that this conflict between the dark energy hypothesis and string theory could lead to testable hypotheses. One of the reasons why some of this speculative cosmological physics tends to bore me is the apparent lack of testable hypotheses. Strictly speaking, unless you can generate testable hypotheses you are not really doing proper science. If we can get some observations that discriminate between some of these ideas, then we will be making real progress.

[hazelm]

Thanks for this Hazel.

 

I know too little about it to make any recommendations but I am very pleased to see that this conflict between the dark energy hypothesis and string theory could lead to testable hypotheses. One of the reasons why some of this speculative cosmological physics tends to bore me is the apparent lack of testable hypotheses. Strictly speaking, unless you can generate testable hypotheses you are not really doing proper science. If we can get some observations that discriminate between some of these ideas, then we will be making real progress.

Perhaps true but who knows what is testable?  Certainly not the person who speculated.  I confess that I would not know a testable hypothesis if it landed on my nose.  But if a suggestion sends me to more information, that I recognize and grab at. 

 

Then - from the other side of the fence  -  there is the opportunity to send a young person to the encyclopedia -- or Wiki.  As long as the person is serious, he is worthy of attention in my estimation.  Learning is fun. Teaching is also fun. 

 

And thank you for what I have learned about physics from you and several others here.  It is the first time I've found  physics interesting enough to look into.

 

Now, back to strings and gravity.  This is a fascinating one.

Edited October 11, 2018 by hazelm

[exchemist]

Perhaps true but who knows what is testable?  Certainly not the person who speculated.  I confess that I would not know a testable hypothesis if it landed on my nose.  But if a suggestion sends me to more information, that I recognize and grab at. 

 

Then - from the other side of the fence  -  there is the opportunity to send a young person to the encyclopedia -- or Wiki.  As long as the person is serious, he is worthy of attention in my estimation.  Learning is fun. Teaching is also fun. 

 

And thank you for what I have learned about physics from you and several others here.  It is the first time I've found  physics interesting enough to look into.

 

Now, back to strings and gravity.  This is a fascinating one.

A testable hypothesis is one that predicts an observation of nature that you should be able to make, if the hypothesis works. Evolution, for instance, predicts that Man's DNA should more closely resemble that of the apes than other creatures, because of the common ancestry, (which it does) and that there should be an intermediate form between a whale and a land mammal (which has been found). And it predicts there should be no rabbits in the Cambrian. (Which there aren't - at least to date!) From these and many similar observations, predicted by, or fitting, the hypothesis, we regard evolution as very sound (though there is a lot being discovered about the detailed mechanisms).  

 

The problem with much exotic cosmological physics is that one cannot often point to something observable, or measurable, that should be so if the hypothesis is sound and not so if it is wrong. However in this case it looks as if string theory is predicting a different expansion rate for the universe from what the dark energy hypothesis predicts. Since we can measure the expansion rate, we now have something to allow us to test which hypothesis is right. This will make whichever one "wins" a lot more "real", as a model of physical reality.     

Edited October 12, 2018 by exchemist

[hazelm]

A testable hypothesis is one that predicts an observation of nature that you should be able to make, if the hypothesis works. Evolution, for instance, predicts that Man's DNA should more closely resemble that of the apes than other creatures, because of the common ancestry, (which it does) and that there should be an intermediate form between a whale and a land mammal (which has been found). And it predicts there should be no rabbits in the Cambrian. (Which there aren't - at least to date!) From these and many similar observations, predicted by, or fitting, the hypothesis, we regard evolution as very sound (though there is a lot being discovered about the detailed mechanisms).  

 

The problem with much exotic cosmological physics is that one cannot often point to something observable, or measurable, that should be so if the hypothesis is sound and not so if it is wrong. However in this case it looks as if string theory is predicting a different expansion rate for the universe from what the dark energy hypothesis predicts. Since we can measure the expansion rate, we now have something to allow us to test which hypothesis is right. This will make whichever one "wins" a lot more "real", as a model of physical reality.     

So far; so good.  Now, "theorem".  If I understand the definition of a theorem correctly, it need not be testable because its hypothesis rests on already tested and shown to be true/acceptable theories.  Correct?   Then, bottom of the stack, "personal theory".  A personal theory can disagree with a tested theory.  I assume this would also need to be testable.  Then the new tests would have to be strong enough to challenge the established theory.  Personal theories seem to be the hardest door to open and gain admission.  By that I mean giving them a fair hearing while saying "no" or "maybe". 

 

If I remember rightly, Wrase's theory has already been challenged.  And all that reminds me of the book "What if Einstein was Wrong?" by Brian Clegg. 

  

Story to be continued and my questions still stand.  Does Gravity fit into this story?  

[exchemist]

So far; so good.  Now, "theorem".  If I understand the definition of a theorem correctly, it need not be testable because its hypothesis rests on already tested and shown to be true/acceptable theories.  Correct?   Then, bottom of the stack, "personal theory".  A personal theory can disagree with a tested theory.  I assume this would also need to be testable.  Then the new tests would have to be strong enough to challenge the established theory.  Personal theories seem to be the hardest door to open and gain admission.  By that I mean giving them a fair hearing while saying "no" or "maybe". 

 

If I remember rightly, Wrase's theory has already been challenged.  And all that reminds me of the book "What if Einstein was Wrong?" by Brian Clegg. 

  

Story to be continued and my questions still stand.  Does Gravity fit into this story?  

A theorem is quite different from a theory. 

 

A theorem is a mathematical entity that proves a conclusion from certain agreed starting points by means of logic. No observation of nature is involved, as it is just an exercise in mathematical logic.

 

Furthermore a key feature of any theory of science is that it cannot be proved. This is quite the opposite of a theorem!  

 

This is because a theory is a hypothesis about the way nature behaves that can always be shown wrong or inadequate if new observations come along that do not fit the theory. As we have no way to be certain what new observations might be made in the future, it must remain logically possible for the theory to be falsified by an unforeseen new discovery.

 

There is nothing wrong with a personal theory per se. All new theories start out that way. However, for a personal theory to be any good, it needs to do better than the theory it seeks to replace. On internet forums we see a great many personal theories in which it is immediately obvious that the author does not even understand the theory he or she seeks to replace, let alone offer something superior. It is probably fair to say that the authors of good quality personal theories are very unlikely to choose internet forums to publish them. :)

 

Gravity has to fit into the string theory and dark energy story, yes. Just don't ask me to explain how.  

Edited October 12, 2018 by exchemist

[hazelm]

I had forgotten that much maligned word "falsifiable".  "Falsifiable" = "capable of being shown to be false".  If a theory is absolutely true, it cannot be shown to be false; therefore, it is not falsifiable.  And that is my pet theory for today. 

 

 

(exchemist):  Gravity has to fit into the string theory and dark energy story, yes. Just don't ask me to explain how.

 

And that is what I have to find out - via someone else's tests.  I am not sure now whether I read it or drew the conclusion that Dark Energy is more gravity. 

 

Then there is dark matter to account for.  Mysteries of the Universe!

 

By the way, in case you haven't noticed, we have somehow gotten two threads going in one  thread.  Is that legal?

[Vmedvil2]

Yes, Gravity does fit into String Theory it would not be a theory of everything if it did not. The Version of String Theory that handles Gravity is 11 dimensional Supergravity. The thing about string theory is there are several different versions of it.

 

Edited October 12, 2018 by VictorMedvil

[hazelm]

Yes, Gravity does fit into String Theory it would not be a theory of everything if it did not. The Version of String Theory that handles Gravity is 11 dimensional Supergravity. The thing about string theory is there are several different versions of it.

 

All right.  "Superstrings" and "Supergravity".  That, perhaps, explains why that joint to Gravity was named "superstrings".  At that time it was considered a speculation.  So, much has been discovered since then.

 

Thank you.  The picture is falling into place here.

[Dubbelosix]

A bit behind the times Hazel, superstring theory and supersymmetric theories are only taken seriously by a select remaining few physicists. You stated:

 

 "Falsifiable" = "capable of being shown to be false".  If a theory is absolutely true, it cannot be shown to be false; therefore, it is not falsifiable.  And that is my pet theory for today. 

 

A theory that is true, amounts to a theory which is supported by experimental evidence. However, the theory remains falsifiable, with any additional data. 

[hazelm]

A bit behind the times Hazel, superstring theory and supersymmetric theories are only taken seriously by a select remaining few physicists. You stated:

 

 "Falsifiable" = "capable of being shown to be false".  If a theory is absolutely true, it cannot be shown to be false; therefore, it is not falsifiable.  And that is my pet theory for today. 

 

A theory that is true, amounts to a theory which is supported by experimental evidence. However, the theory remains falsifiable, with any additional data. 

I know, Dubbelosix.  I was quoting from an old argument that took place long ago.  My argument is not with whether something is falsifiable.  My argument is with the word that was chosen to support the premise.  And, yes, it goes back a long, long way.  It's just that its definition does not fit its usage.

 

But, nevermind.  We have a few other words in our language that are the same problem.  We deal with them.  Sometimes we even forget there is an issue. :-)

[Vmedvil2]

It is not completely true that String Theory is not able to be proven false, it is just with the level of technology that humans have it is unable to be proven false, you would need a way to measure a Planck length or String Length in order to prove it right or wrong which beyond human ability for the time being. It is not the first theory to have this issue, if you want to prove it false then begin construct on a Planck level measurement device, I won't stop you.

Edited October 14, 2018 by VictorMedvil

[hazelm]

It is not completely true that String Theory is not able to be proven false, it is just with the level of technology that humans have it is unable to be proven false, you would need a way to measure a Planck length or String Length in order to prove it right or wrong which beyond human ability for the time being. It is not the first theory to have this issue, if you want to prove it false then begin construct on a Planck level measurement device, I won't stop you.

I'll let you do the building.  The math would defeat me.  :-)    That said, how do you really prove anything about an unreachable universe?  It's only what we see.  But the, we once "saw" that Planet Earth is flat and that the Sun revolves around Earth.  :-)

[A-wal]

That said, how do you really prove anything about an unreachable universe?  It's only what we see.  But the, we once "saw" that Planet Earth is flat and that the Sun revolves around Earth.  :-)

It's not proved, it's modeled. A useful model makes observable predictions. If those predictions are true (without adding never before seen 'dark' processes/substances) then it's a working (not proven) model. The flat Earth and geocentric models both make predictions that falsify those models. The best models are the simplest ones that make the most correct predictions.

[hazelm]

It's not proved, it's modeled. A useful model makes observable predictions. If those predictions are true (without adding never before seen 'dark' processes/substances) then it's a working (not proven) model. The flat Earth and geocentric models both make predictions that falsify those models. The best models are the simplest ones that make the most correct predictions.

I know you are right.  But there is so much that sounds so impossible.  So much running through my head that I'd better not say.    But, please remember that my "protest" is not against what is right or wrong; proven or disproven, etc.  My protest is against the label being used to prove/disprove.  But languages change meanings all the time.  Why would I quibble over one word?  Especially since it begins to make sense.  :-)

 

Thanks.  Back to the OP.  Has anyone written a good but simple book about the interrelationship of gravity, superstrings and dark energy?  I wonder if John Barrow is still around and working.  He could write a follow-up to his 1994 book. 

[A-wal]

Has anyone written a good but simple book about the interrelationship of gravity, superstrings and dark energy?

I don't know. String theory attempts to unify gravity with the other three forces, something that hasn't been done successfully, the so called theory of everything. Dark energy is supposedly a repulsion so it would require that gravity pushes rather than pulls over a certain distance (presumably depending on the mass). An interesting thought but I don't even believe in dark energy. I don't think string theory has anything to do with dark energy but I might well be wrong.

[hazelm]

I don't know. String theory attempts to unify gravity with the other three forces, something that hasn't been done successfully, the so called theory of everything. Dark energy is supposedly a repulsion so it would require that gravity pushes rather than pulls over a certain distance (presumably depending on the mass). An interesting thought but I don't even believe in dark energy. I don't think string theory has anything to do with dark energy but I might well be wrong.

This is what I am trying to find.  24 years ago (dark energy unheard of, I think) Barrow did say the superstring connection to gravity was speculation and that a lot of research needed to be done.  I guess it is all still up in the air.   Maybe another 24 years?