Dark Energy and Non-Conservative Forces

[studiot]

Another reason for not combining replies with the original is this.

This is what happens if I use the quote button on your post that I complained about.

 

3 hours ago, DLTherrien said:

 

 

None of what you said comes out!

 

This effectively prevents or makes difficult for other members to quote your words to reply to them.

 

Now we have sorted all that, perhaps you could repost those words so that Marcus and I can thing of something to say about them?

 

[DLTherrien]

Actually I believe Marcus has answered most of my questions already and his suggestion is for me to learn more about GR which I assume means General Relativity and I have been trying. I have watched uncountable videos and sat through videos of debates about it including time itself which includes several and different experts in the fields who while trying to not use the math to explain have still left me with the same misunderstanding of what it all really means. I have also read through many articles about the same topics. All of this I do online due really to time constraints with a full time job and classes I am taking at Berkelee for audio production. I am writing this at work on a laptop in my truck. After Marcus's suggestion today on GR, I googled this. "General Relativity explained without the math" and I came up with this which seems to be a decent explanation and has helped me to understand much more. It is a short video and I will be watching others from the same author later but if you could, could you watch and tell me if it is a good way for me to understand it better? 

 

[Markus Hanke]

1 hour ago, DLTherrien said:

All of this I do online due really to time constraints with a full time job and classes I am taking at Berkelee for audio production.

I have to be honest and say that you would be better off investing the time you spend on YouTube into studying a proper textbook on GR. There are two main reasons for this:

1. GR is a 4-dimensional model. As such, no visual representation will ever allow you to gain a full understanding of gravity, since it is not possible to accurately embedd a 4D manifold into a 2D+1 screen representation. Any such attempt will necessarily be flawed, and can thus lead to serious misunderstandings of what GR actually says.

2. YouTube is not a valid source of scientific data. How do you know that what you see in a video is a an accurate representation of GR, especially if you are unfamiliar with the model? 

I do realise that the maths of GR seem very intimidating at first, and I do not deny that some considerable effort is initially needed to get your head around the formalism. But once you do, you no longer have to rely on incomplete and flawed analogies; the meaning and physics of GR become self-evident, once you know how to read the formulas. And that’s all you need to be able to do - understand the physical meaning of the equations. For a layperson it is not necessary to be able to work with them. But understanding them is not such a tall order.

1 hour ago, DLTherrien said:

It is a short video and I will be watching others from the same author later but if you could, could you watch and tell me if it is a good way for me to understand it better?

No! What is described in the video does not represent the current scientific consensus on gravity. It is a mixture of established facts, hypothetical/unconfirmed ideas from current research into quantum gravity, and personal speculations by the author which have no basis in established physics at all. It would be difficult and time consuming now to try and disentangle these strands for you, so I won’t try. Suffice to say that this is the reason why you shouldn’t rely on random YouTube videos when trying to understand GR.

I have no doubt that there will be decent YouTube presentations on the topic, though I can’t give you any links, since I seldom use that platform; I self-study only from textbooks, since in my opinion that is the only way to really develop a proper understanding of the subject matter. I’m afraid there are simply no shortcuts here.

At the danger of getting myself into trouble with the moderators here (please delete if not allowed), I will link you to a “First Primer for Laypeople” style introduction to GR, which I wrote some years ago. It contains almost no math at all, but does present the main ideas of GR in a way that I hope is understable even for a complete newbie:

http://www.markushanke.net/general-relativity-for-laypeople-a-first-primer/

Hopefully this is helpful to you. There is also a link there to another article of mine, which is a (more or less) gentle introduction to the mathematics of GR. You may wish to have a read there, too.

Edited July 9, 2018 by Markus Hanke

[StringJunky]

14 minutes ago, Markus Hanke said:

I have to be honest and say that you would be better off investing the time you spend on YouTube into studying a proper textbook on GR. There are two main reasons for this:

1. GR is a 4-dimensional model. As such, no visual representation will ever allow you to gain a full understanding of gravity, since it is not possible to accurately embedd a 4D manifold into a 2D+1 screen representation. Any such attempt will necessarily be flawed, and can thus lead to serious misunderstandings of what GR actually says.

2. YouTube is not a valid source of scientific data. How do you know that what you see in a video is a an accurate representation of GR, especially if you are unfamiliar with the model? 

I do realise that the maths of GR seem very intimidating at first, and I do not deny that some considerable effort is initially needed to get your head around the formalism. But once you do, you no longer have to rely on incomplete and flawed analogies; the meaning and physics of GR become self-evident, once you know how to read the formulas. And that’s all you need to be able to do - understand the physical meaning of the equations. For a layperson it is not necessary to be able to work with them. But understanding them is not such a tall order.

No! What is described in the video does not represent the current scientific consensus on gravity. It is a mixture of established facts, hypothetical/unconfirmed ideas from current research into quantum gravity, and personal speculations by the author which have no basis in established physics at all. It would be difficult and time consuming now to try and disentangle these strands for you, so I won’t try. Suffice to say that this is the reason why you shouldn’t rely on random YouTube videos when trying to understand GR.

I have no doubt that there will be decent YouTube presentations on the topic, though I can’t give you any links, since I seldom use that platform; I self-study only from textbooks, since in my opinion that is the only way to really develop a proper understanding of the subject matter. I’m afraid there are simply no shortcuts here.

At the danger of getting myself into trouble with the moderators here (please delete if not allowed), I will link you to a “First Primer for Laypeople” style introduction to GR, which I wrote some years ago. It contains almost no math at all, but does present the main ideas of GR in a way that I hope is understable even for a complete newbie:

http://www.markushanke.net/general-relativity-for-laypeople-a-first-primer/

Hopefully this is helpful to you. There is also a link there to another article of mine, which is a (more or less) gentle introduction to the mathematics of GR. You may wish to have a read there, too.

I'll have a gander.

[DLTherrien]

30 minutes ago, Markus Hanke said:

Hopefully this is helpful to you. There is also a link there to another article of mine, which is a (more or less) gentle introduction to the mathematics of GR. You may wish to have a read there, too.

Thank you I have found also that the information I find in videos has been difficult not only to understand bit to trust especially depending on when they were created compared to the ever changing ideas on what is fact. I am going to read your links and try to find more time to dive into books on the subject. I really appreciate all of your and others very patient help on this. I will get it eventually. I have been trying to slowly learn the math also. Thanks again. 

Edited July 9, 2018 by DLTherrien

[studiot]

Thank you for your link, Marcus.

Very interesting.

DLT, I'm sorry to say that you will require substantial facility/familiarity with maths not taught until well into University to properly read Marcus' offering.

I am not sure about that Ytube vid. It contains some interesting ideas, some unsubstantiated as Marcus said.

I was rather perturbed by the linking of gravity to electrostatic effects. As far as we know ther is no such link.

 

Earlier in this thread I asked why you do not read books, several have been suggested and you still haven't said anything about this.

So I have chosen 2 books to suggest.

The first is a very modern, non mathematical introduction to and history of General Relativity (Did you know the there have been several versions, the Man himself changed it three times) by the Professor of Astrophysics at Oxford University.

Pedro G Ferreira

The Perfect Theory

 

Secondly  a book that will grow on anyone using it.

Dynamics and Relativity by

W D McComb (University of Edinburgh)

offers background, explanations and insights as well as the simpler (but correct) mathematics developed from classical mechanics to full blown GR but without the fancy symbolism that so often gets in the way.

It will also help you cross correlate what Marcus is saying.

If you come across something you don't understand you can always ask here at SF.

 

 

 

Edited July 9, 2018 by studiot

[DLTherrien]

1 hour ago, studiot said:

Earlier in this thread I asked why you do not read books, several have been suggested and you still haven't said anything about this.

So I have chosen 2 books to suggest.

Thank you. I must have missed the suggestions. I will aquire those you suggest. It is obvious I need to re-think my approach to learning and I thank all of you for your help.

Edited July 9, 2018 by DLTherrien

[DLTherrien]

1 hour ago, studiot said:

If you come across something you don't understand you can always ask here at SF.

Real quick question. I get now that time moves slower for the reasons stated but I have to ask this. So, If I was to travel near the speed of light; even half that speed, does it mean I will age slower and perhaps live a thousand years or does it just mean you here on earth will age.... See, I don't even know how to ask the question. I guess a good way to ask would be with this scenario. Say we hypothetically of course; gradually increased the gravity on earth over we'll say the next 500 years so our bodies would adjust; would that be a way to make us live longer or would we still have the same life span. I guess the one question that throws me as far as the time thing is that. Would it still seem like 80 to 100 years or would it now be more like 300? I'm so confused.

[beecee]

49 minutes ago, DLTherrien said:

Real quick question. I get now that time moves slower for the reasons stated but I have to ask this. So, If I was to travel near the speed of light; even half that speed, does it mean I will age slower and perhaps live a thousand years or does it just mean you here on earth will age.... See, I don't even know how to ask the question. I guess a good way to ask would be with this scenario. Say we hypothetically of course; gradually increased the gravity on earth over we'll say the next 500 years so our bodies would adjust; would that be a way to make us live longer or would we still have the same life span. I guess the one question that throws me as far as the time thing is that. Would it still seem like 80 to 100 years or would it now be more like 300? I'm so confused.

Time always passes at one second per second for every person and all mechanical clocks tick at the rate of one second per second within each one's own frame of reference. One will only ever see a clock or person age slower or quicker in another frame.

If you and I were twins, and I being the more intrepid, decide to take off in a warp drive ship at 99.999% c and return 12 months later according to my on board ship's clocks, I will return having aged 12 months, but everything else on Earth will have aged 230 years approximately and you would be long dead and buried.

Edited July 9, 2018 by beecee

[DLTherrien]

3 minutes ago, beecee said:

One will only ever see a clock or person age slower or quicker in another frame.

OK, so if I understand you correctly, we will both feel as if we aged properly. That is bizarre! I like it.  I actually bought my first book just now,. I believe you recommended some for me as did another but I could not find his at Barnes and Noble so I decided to get my feet wet with Steven Hawking's .. "The grand design" Will be digging in tonight after class. I will check your list also. 

[beecee]

41 minutes ago, DLTherrien said:

OK, so if I understand you correctly, we will both feel as if we aged properly. That is bizarre! I like it.  I actually bought my first book just now,. I believe you recommended some for me as did another but I could not find his at Barnes and Noble so I decided to get my feet wet with Steven Hawking's .. "The grand design" Will be digging in tonight after class. I will check your list also. 

Yep, that's about it..each person will always feel time passing as per normal at one second per second. But for example with the scenario I described above, If I can look back at you, I will see your time going slower and you looking at me, will see my time going slower. Now this may sound rather contradictory but it has something to do with the equivalence principal and the fact that it would be just as valid for me to say that you were the one moving at 99.999% c as it is for you. But the "difference"  then becomes obvious when I need to accelerate/decelerate to turn around and return to Earth. That's putting it in basic layman's terms of which as I said, I am one, so if any of our experts and others with more knowledge would like to tidy up, then be my guest.

 

PS: The first book that really got me interested in this stuff at this level was Stephen Hawking's  "A Brief History of Time"  

Edited July 9, 2018 by beecee

[DLTherrien]

5 minutes ago, beecee said:

PS: The first book that really got me interested in this stuff at this level was Stephen Hawking's  "A Brief History of Time"  

I had that one in my hand but chose the other., That will be my next one. Thanks.

[beecee]

It is known as " The Twin Paradox"  when there is really no paradox according to SR.

https://en.wikipedia.org/wiki/Twin_paradox

In physics, the twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling because each twin sees the other twin as moving, and so, according to an incorrect[1][2] and naive[3][4] application of time dilation and the principle of relativity, each should paradoxically find the other to have aged less. However, this scenario can be resolved within the standard framework of special relativity: the travelling twin's trajectory involves two different inertial frames, one for the outbound journey and one for the inbound journey, and so there is no symmetry between the spacetime paths of the twins. Therefore, the twin paradox is not a paradox in the sense of a logical contradiction.

[DLTherrien]

2 minutes ago, beecee said:

It is known as " The Twin Paradox"  when there is really no paradox according to SR.

https://en.wikipedia.org/wiki/Twin_paradox

In physics, the twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling because each twin sees the other twin as moving, and so, according to an incorrect[1][2] and naive[3][4] application of time dilation and the principle of relativity, each should paradoxically find the other to have aged less. However, this scenario can be resolved within the standard framework of special relativity: the travelling twin's trajectory involves two different inertial frames, one for the outbound journey and one for the inbound journey, and so there is no symmetry between the spacetime paths of the twins. Therefore, the twin paradox is not a paradox in the sense of a logical contradiction.

HUH? Don't try to elaborate. I will read up on it thanks. 

[studiot]

Beware of 'popular science' (popsci) books which are usually showmanship with little substance.

Here is a superb (old) book that is long on explanatory words and short on fancy maths from the man who proved General Relativity experimentally,

Sir Arthur Eddington.

The first scan shows a picture of the apparatus and title page.

The second the contents page

The third is his more colourful account of the twins paradox using a man with a cigar.

 

 

[DLTherrien]

4 hours ago, studiot said:

Here is a superb (old) book

Cool. Thanks I will check it out. I am about halfway through Hawking's The Grand Design. Just starting to get interesting. So, in 1966 they still believed in the aether? Even spell check doesn't believe in that Last ten or so lines of page 25. Most likely will have to order that online. Barnes And Noble didn't have the two you offered. Have to order them also. 

[Eise]

13 hours ago, Markus Hanke said:

I have no doubt that there will be decent YouTube presentations on the topic

Yes, I think there are. This is my favourite on the topic of GR. No rubber sheet (the maker of the video actually criticises the sheet analogy), but a demonstration with (his own built?) spacetime stretcher. Just 4m:12s. Until now I haven't seen a better video on gravity according to the GR for lay people. 

DLTherrien, try it out!

[studiot]

4 hours ago, DLTherrien said:

Cool. Thanks I will check it out. I am about halfway through Hawking's The Grand Design. Just starting to get interesting. So, in 1966 they still believed in the aether? Even spell check doesn't believe in that Last ten or so lines of page 25. Most likely will have to order that online. Barnes And Noble didn't have the two you offered. Have to order them also. 

As can be seen from the page facing the contents page, Eddington's book was actually published in 1920, following the famous experiments. My copy is one of the many reprints dated 1966 as you spotted.

In fact, although he refers to an aether, he develops the argument against it, though that is not totally clear from the short extract, which actually starts in line 25 of page 24.

If you want the flow blown works he is also the author of the definitive

'The Mathematical theory of Relativity ', also from Cambridge University Press.

 

As a matter of interest, I'm not sure about McComb, but the books I mention can usually be obtained second hand or remaindered at low cost.

 

Edited July 10, 2018 by studiot

[DLTherrien]

4 hours ago, Eise said:

Yes, I think there are. This is my favourite on the topic of GR. No rubber sheet (the maker of the video actually criticises the sheet analogy), but a demonstration with (his own built?) spacetime stretcher. Just 4m:12s. Until now I haven't seen a better video on gravity according to the GR for lay people. 

DLTherrien, try it out!

That was a cool way for sure to explain it. I get the whole idea of space time though. Have for some time although I still have questions and doubts about some of the concept such as if time is also a wave, (Possible)  how do we know we do not always interrupt the experiment by observing it like it or not and there is no way to come up with a different answer?  What I want to know is everything else. My main interest although cosmology and astrology is also interesting is the Quantum world. Time and space for me is really just a side show to that. For that reason I find string theory a path that I am waiting for some answers to develop although it even in name and description will most likely change once something more is understood if ever. There might be a limit to what we will ever know about it. What can be observed directly through experiment might have its limits even at close range. 

Even before I started to study this stuff I always had the idea crazy as it sounds that the farther we look, we will always find more in our universe partly because it is created by us observing it. After reading a book which was a suggested path to take by others here instead of the internet which i immediately have found is better, and that book being Stephen Hawking's ... The Grand Design, I am learning I may not have been that far off in that theory or like Einstein liked to call it; a thought experiment. Deep I know but if we can truly change the past of a particle by observing it and particles can be seemingly anywhere and everywhere at the same time until observed, how do we know an entire planet or a star could not be formed in and instant by doing the same for countless particles at once just with a glance. There very well could be more to it when it comes to consciousness. Suddenly there is a billions of years old star out of no where because the past choices made by all of those particles at different times for all have just been changed and like the lottery, we have a winner! 

Are we capable of much more that we know and does it only apply to humans or does anything with a conscious mind also have the same innate or to stick with the favorite scientific synonym ... intrinsic abilities? If we were not here to observe it, would it really be here? My mind has been "lost in space" for a long time.

 

3 hours ago, studiot said:

Eddington's book was actually published in 1920

I am interested for sure in the read. I am immediately finding as you and others have said that books are a better way to study and that will be my path for now on. The one I am reading now starts at the known beginning of science in general and by following that path it has made it far easier to understand how we got to the point we are now. Addicted. Couldn't put it down. Four hours sleep. Gonna be a long day at work. I am going to search Amazon for the titles you recommend and others I cannot find in stores. Only way I know of to find even used Physics books other than perhaps E-Bay which I do not trust. When at Barnes And Noble, I looked for the aisle trying to find books on Physics and not such a popular aisle. I had to ask. Tucked way back in the corner in the science section. When I asked, I got he look of "But Why?"

[studiot]

1 hour ago, DLTherrien said:

Only way I know of to find even used Physics books other than perhaps E-Bay which I do not trust

Ebay is fine but also look here

 

Abebooks.co.uk

[StringJunky]

4 hours ago, studiot said:

As can be seen from the page facing the contents page, Eddington's book was actually published in 1920, following the famous experiments. My copy is one of the many reprints dated 1966 as you spotted.

In fact, although he refers to an aether, he develops the argument against it, though that is not totally clear from the short extract, which actually starts in line 25 of page 24.

If you want the flow blown works he is also the author of the definitive

'The Mathematical theory of Relativity ', also from Cambridge University Press.

 

As a matter of interest, I'm not sure about McComb, but the books I mention can usually be obtained second hand or remaindered at low cost.

 

Have you read  A most incomprehensible thing by Peter Collier? I have it but I haven't read it yet. It's a layman's mathematical introduction.

https://www.amazon.com/Most-Incomprehensible-Thing-Introduction-Mathematics-ebook/dp/B008JRJ1VK

[DLTherrien]

57 minutes ago, StringJunky said:

Have you read  A most incomprehensible thing by Peter Collier? I have it but I haven't read it yet. It's a layman's mathematical introduction.

Excellent. Will do. Thanks.

[StringJunky]

4 minutes ago, DLTherrien said:

Excellent. Will do. Thanks.

I would look at this subject as a very long term project, which is what I intend to do when I've committed myself. Get a feel for the Relativity landscape and then zone in, slowly, into the details. 

[DLTherrien]

Confucius says: "Man with watch always knows the time. Man with two watches is never sure."

Confucius needed to lay off the pharmaceuticals. Walking around with two sundials on your wrist is just silly.

As far as what you say about zoning in; that is my intention eventually..

[StringJunky]

1 minute ago, DLTherrien said:

Confucius says: "Man with watch always knows the time. Man with two watches is never sure."

Confucius needed to lay off the pharmaceuticals. Walking around with two sundials on your wrist is just silly.

As far as what you say about zoning in; that is my intention eventually..

LOL! Yeah!

As far as 'zoning in', the first thing to accept is that those things outside of our direct experience do not follow the same rules of commonsense... that is the first hurdle. I suggest thinking like a child and just accept what you read; by relativity experts only, of course. It does gradually make sense in the end. If you keep reading and asking here you'll get used to the ideas and language of relativity, which helps a lot.