The Naked Scientists

The Naked Scientists Forum

Author Topic: How does light speed up when it exits a denser material?  (Read 27006 times)

Offline jeffreyH

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 3913
  • Thanked: 53 times
  • The graviton sucks
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #75 on: 14/08/2015 00:29:50 »
Firstly Timey I didn't say that light took a spiral path. Secondly you cannot simply use speculation to formulate hypotheses. Most of the discoveries in physics followed on from experimentation where the equations were derived to understand the mechanism at work. Not the other way round. Thirdly don't follow me. I am untrained and this is just a hobby for me. The way I do things is not the correct way as understood by professional physicists. I have studied the areas I need to for those things I am interested in at the time. If you have an interest in quantum physics then try to find out why 0365e3a489471c7d076b85f16a5c1de4.gif is important and what it means. It is to do with the electron. Also try to find out what <a|b><a|b>* means. It is to do with probability. These are not difficult and are just linear algebra (matrices). It will surprise you. You will also learn what a complex conjugate is and how it relates to the complex plane.
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #76 on: 14/08/2015 01:42:24 »
Firstly Jeff, I'm not 'following' you.  LOL !!! ...did you think you were guru type material???

Secondly, I am perfectly aware that speculation cannot be used to form a hypothesis. 

Thirdly, most of the 'experiments' conducted were conducted because """someone""" speculated a reason that they should be conducted.

My understanding of quantum is sufficient for my purposes.  I have also read extensively in my area of interest, thank you.  Why is is that it is always assumed when one makes a suggestion that this is based on a misunderstanding of the subject matter???  I do NOT understand maths.  I need a description in words.  I am well acquainted with Heisenberg's principle.  I think I mentioned earlier in this thread that I have read Quantum, by Manjit Kumar and am in fact reading it again at this present time.

P.S . I did not say that you said that light follows a spiral path.

Keep it civil - Mod.
« Last Edit: 14/08/2015 12:01:32 by evan_au »
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #77 on: 14/08/2015 03:51:59 »
To sum up the world of quantum, on a basic level there isn't really a lot to it.  Particles have spin, spin can be oriented.  If you orient a particle it's spin will remain oriented in that direction.  Therefore, we can harness the electron to our purpose.  We have to take round the houses methods in order to calculate quantum through probability because p x q does not sum up to the same as q x p, this being because when attempts are made to measure simultaneously a pair of conjugate variables: position and momentum or energy and time, the limitations of these concepts become evident.

Anyone else wish to condescend me?
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #78 on: 14/08/2015 06:27:34 »
Look Jeff, having evened my temper with an egg and bacon sandwich, and a cup of tea, I am back to tell you that you are right in the fact that I read your posts.  But I also read a lot of other peoples posts too.  It's not everybody's posts that I come back to though.  Interestingly enough it is for the very reasons you say I should stay away, that I do come back to your posts.  My only complaint being that you do not include more written explanation of your intent, direction, and findings in words.  I think even a mathematician 'might' agree.
 

Offline Colin2B

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1917
  • Thanked: 123 times
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #79 on: 14/08/2015 10:58:32 »
We use imaginary and complex numbers as a way to determine eigenvalues. Those numbers don't exist and yet they are used.
Sorry, late reply, been away.
I always felt that imaginary numbers were misnamed as they relate to real things.
Take AC voltage current, normally inphase but in an inductive load complex numbers give us the phase relationship between the 2. Similarly, in Fourier Analysis they can show the relationship betwen frequencies and phase. These are not unreal relationships.
 

Offline jeffreyH

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 3913
  • Thanked: 53 times
  • The graviton sucks
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #80 on: 15/08/2015 12:51:00 »
To sum up the world of quantum, on a basic level there isn't really a lot to it.  Particles have spin, spin can be oriented.  If you orient a particle it's spin will remain oriented in that direction.  Therefore, we can harness the electron to our purpose.  We have to take round the houses methods in order to calculate quantum through probability because p x q does not sum up to the same as q x p, this being because when attempts are made to measure simultaneously a pair of conjugate variables: position and momentum or energy and time, the limitations of these concepts become evident.

Anyone else wish to condescend me?

I meant following my example. You do pick up the general idea which is good. The mathematics is the interesting part of the physics. Without a clear understanding you can miss the subtleties.
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #81 on: 15/08/2015 14:18:53 »
Which is why I have been using the internet extensively to visit places like Stamford University to study advanced mathematics with the benefit of explanation in words.  However...yes... I'm sure that I 'have' missed some of the subtleties of, in particular, the GR field equations.  But Jeff, it's one thing to understand these mathematics and quite another to then turn them to one's own purpose...

Sometimes one has to accept the imitations (Edit: That should be 'limitations' but I'll leave it in for humours sake :). ) of ones own abilities.  This therefore being my reason for posting my ideas to see if I can inspire any interest.  I know... :) , you're busy, we've established that!

I'm sorry I flew off handle and wish you all the best.
« Last Edit: 15/08/2015 14:35:27 by timey »
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #82 on: 15/08/2015 18:46:03 »
Actually, on reflection I think it fair to tell you that it was the fact that your post suggested that I should further my idea through investigation of the calculation of quantum probability that I found annoying, as this is entirely contrary to the very nature of my suggestion.  However it does occur to me (slowly, I admit) that the implications of my notion have perhaps evaded you...
 

Offline jeffreyH

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 3913
  • Thanked: 53 times
  • The graviton sucks
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #83 on: 15/08/2015 21:00:54 »
What notion would that be then?
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #84 on: 15/08/2015 21:28:34 »
What notion would that be then?

Well that would be the notion laid out in post 49, bottom of page 2, that you answered saying:

"Well now that you are being clearer in meaning you are saying something interesting"

Good job I have a photographic memory because you have somehow completely deleted that post, but it is evident that you made this reply in the fact of my reply, now classed as post 50, top of page 3, teaching me a valuable lesson in the relevance of "quoting" :)

(Edit: Your exact wording was "Now you are clearer in meaning and are saying something interesting")
« Last Edit: 15/08/2015 21:54:44 by timey »
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #85 on: 17/08/2015 03:10:19 »
I meant following my example.

I'm sorry, I cannot think of one instance whereas I 'have' followed your example.

To re-iterate a couple of points that got edited out of post 76, this time minus the scathing sarcasm:

I'd like to remind you that it was you who came speaking to me on my thread where I was asking for mathematical help.  You encouraged me to "bounce your ideas off me", these being your very words.

You have now, despite my explaining to you more than several times that I need a full explanation of mathematical process in words, 3 times posted me maths equations without explanation.
This is in as much as my speaking both English and Spanish, whereas I know you speak only English, and my posting supposed answers or suggestions to your posts in Spanish without translation.  I'm sure you would consider this to be an act of, if not rudeness, then severe illogicality!

The fact that your response to my notion in post 49 has been deleted is also an illogicality.  Illogicalities raise red flags in my book.  They spell the existence of an incomplete picture!  Now that the "notion" in question has been identified, do you have a response?

For what reason, under the remit of the nature of my suggestion, would your suggestion of my necessity to study the mathematics of quantum probability, (outside of the fact that p x q does not sum up to q x p), actually be 'relevant' to my cause?

... because it would seem to me that studying the Planck unit in relation to particle mass would actually be a much more logical approach, wouldn't you agree?
« Last Edit: 17/08/2015 03:18:04 by timey »
 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #86 on: 17/08/2015 03:42:23 »
Quote from: timey
... outside of the fact that p x q does not sum up to q x p ...
I don't understand this. What do you mean by p x q does not sum up to q x p?

In quantum mechanics, if p and q are operators, "x" is the cross product then p x q does not equal q x p. Is this what you meant?
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #87 on: 17/08/2015 03:49:10 »
Yes. Heisenberg's uncertainty principle to be precise.
 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #88 on: 17/08/2015 05:09:51 »
Yes. Heisenberg's uncertainty principle to be precise.
That's incorrect. In anycase I wanted to know what you mean by "p x q does not sum up to q x p"?

Heisenberg's uncertainty principle is not directly related to the fact that in general operators corresponding to observables don't commute. However sometimes they do. Here's why: two operators are said to commute if AB = BA. The commutator of A and B, denoted as [A, B], is defined as

[A, B] = AB - BA

If A and B commute then [A, B] = 0. It can be shown that delta A * delta B >= (1/2)|<[A, B]>| where <Q> is the expectation of Q and |a| is the magnitude of a. Therefore if [A, B] = 0 then delta A * delta B = 0.

For these reasons I once again ask what you mean by "p x q does not sum up to q x p"?
« Last Edit: 17/08/2015 05:18:43 by PmbPhy »
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #89 on: 17/08/2015 05:36:29 »
"The uncertainty discovered by Heisenberg is an intrinsic feature of reality.  There could be no improvement, he argued, on the limits set by the size of Planck's constant and enforced by the uncertainty relations in the precision of what is observable in the atomic world.
The fundamental equation of quantum mechanics, pq-qp=ih/2(symbol I can't include), where p and q are the momentum and position of a particle.  It was the inherent uncertainty of nature that lay behind non-commutativity - the fact that pxq does not equal qxp."

Quoted directly from Manjit Kumar's book "Quantum".
 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #90 on: 17/08/2015 07:00:37 »
Yeah, I know that all too well as any physicist would, i.e. it's the canonical commutation relation for position and momentum (which are canonically conjugate observables). However it's not Heisenberg's uncertainty principle. It's barely related to it either. The only connection is as I'll explain below.

Note: I assume the symbol you're referring to is4f08e3dba63dc6d40b22952c7a9dac6d.gif, right? I'm going to use 0883aecb4ef0d44b183e543352f9a6aa.gif

Question:You didn't know the name for pi? pi is a Greek symbol which you can include here by using Latex.

The commutator for position, p and momentun, q, is pq - qp = [p, q]. Therefore

3a746a40f6d44b871805ec6e5611ca6c.gif

We place this into delta A * delta B >= (1/2)|<[A, B]>| and we get the Heisenberg uncertainty principle (it's really a theorem because it can be derived), i.e.

delta A * delta B >= (1/2)|<[A, B]>| = (1/2)|<995c7e5c27b9c24a90247052ac9c05cc.gif>| = h/44f08e3dba63dc6d40b22952c7a9dac6d.gif or more simply put

delta A * delta B >= h/44f08e3dba63dc6d40b22952c7a9dac6d.gif

Again I ask - What do you mean by "p x q does not sum up to q x p?"

Can't you simply explain what you meant when you posted that comment? I.e. please define the phrase "does not sum to". Do you mean "Does not equal"? If so then that would make a great deal of sense. If that's the case then it was a language barrier problem.
« Last Edit: 17/08/2015 07:02:36 by PmbPhy »
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #91 on: 17/08/2015 10:49:38 »
I'm sorry Pete, but I actually did answer your question of "do I mean "equal?"...
In England "sum" can mean add".  If something doesn't add up, they are not equal.  So what I was saying was that pxq does not add up to, sum to, or equal the same as qxp.  Ok?
So when I replied "yes" in post 87, that was indeed what I was saying yes to!

However, I am experiencing a weird sense of symmetry going on here with regards to my posts, whereas Jeff seems to have completely lost his tongue simultaneously to you having just found yours...therefore, thank you for pointing out the finer details of the Uncertainty Principle, but perhaps you would care to explain to me, under the remit of my notion set out in post 49, why Jeff's suggestion:

If you have an interest in quantum physics then try to find out why 0365e3a489471c7d076b85f16a5c1de4.gif is important and what it means. It is to do with the electron. Also try to find out what <a|b><a|b>* means. It is to do with probability.

...would be relevant in the furthering of my cause?

P.S.  Yes, of course I know the name for 'pi' and what 'pi' is, and now I can relate that to the symbol.  If I come across that symbol again and have to describe it, now I'll know what to say, so thanks.  Learn something new everyday, aye!
 

Offline lightarrow

  • Neilep Level Member
  • ******
  • Posts: 4586
  • Thanked: 7 times
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #92 on: 17/08/2015 11:03:49 »
I'm sorry Pete, but I actually did answer your question of "do I mean "equal?"...
In England "sum" can mean add".  If something doesn't add up, they are not equal.
But it's not true the opposite, infact you can sum up something which is not equal, for example 2+5. In our case we have the operator pq which is not equal to the operator qp. Does it mean they don't sum up? No! Infact they can. Theyr sum is called "anticommutator of p and q" and is a well defined operator.

--
lightarrow
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #93 on: 17/08/2015 11:41:20 »
Lol!  Are we actually debating the definition and use of words here???

What about the question in hand? (she growled)
 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #94 on: 17/08/2015 13:44:19 »
Quote from: timey
I'm sorry Pete, but I actually did answer your question of "do I mean "equal?"...
As I said, it's a language barrier. If there is a next time then when someone asks a question like
Quote
What do you mean by "p x q does not sum up to q x p?"
Then just say "they aren't equal" rather than all that stuff you replied with.

Note: A bit of friendly advice; If this happens again then just explain what you meant directly. Here you could have simply said from the beginning "they aren't equal".

Quote from: timey
In England "sum" can mean add".  If something doesn't add up, they are not equal.  So what I was saying was that pxq does not add up to, sum to, or equal the same as qxp.  Ok?
As I said; language barrier.

Quote from: timey
So when I replied "yes" in post 87, that was indeed what I was saying yes to!
But when you followed that by an irrelevant reference to Heisenberg's principle it lost its meaning.

If you have an interest in quantum physics then try to find out why 0365e3a489471c7d076b85f16a5c1de4.gif is important and what it means. It is to do with the electron. Also try to find out what <a|b><a|b>* means. It is to do with probability.
This was an unfair suggestion by Jeff since he didn't defined his terms. The sigmas remind me of the Dirac notation but that comment doesn't bring anything to mind. It's not as if people readily remember everything from all fields unless they spend a great deal of time working with/studying that field.
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #95 on: 17/08/2015 14:26:09 »
Thanks!  Advice taken, 'sum up' has now been banished from my vocabulary with regards to mathematical definition of 'equal'.  We could get into a discussion about the term 'equals' in relation to a 'summing up', but you know...perhaps there 'are' better things we could do with our time...

(Tried quoting but it's not working)

I'm sorry, but I don't really think one has to spend a great deal of time studying a field to realise that a suggestion that questions the mathematical structure of Planks h constant, due to a possible factor of quantum time dilation actually relates only as far as Heisenberg's uncertainty principle, and that any investigation into calculating quantum probability is totally and utterly irrelevant and has no bearing whatsoever on the structure of Planck's h constant.

In fact one of the the most logical approaches would be to study the Planck unit in relation to particle mass.

May I suggest you partake of a hot chocolate with brandy and let Jeff answer for himself?
 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #96 on: 17/08/2015 15:29:04 »
Quote from: timey
I'm sorry, but I don't really think one has to spend a great deal of time studying a field to realise that a suggestion that questions the mathematical structure of Planks h constant, due to a possible factor of quantum time dilation actually relates only as far as Heisenberg's uncertainty principle, and that any investigation into calculating quantum probability is totally and utterly irrelevant and has no bearing whatsoever on the structure of Planck's h constant.

In fact one of the most logical approaches would be to study the Planck unit in relation to particle mass.
I don't understand this comment. What is it that you are referring to? Was it something I said?

Quote from: timey
May I suggest you partake of a hot chocolate with brandy and let Jeff answer for himself?
Of course. However I never suggested that I was going to do otherwise. All my comment was for was to say that I think that wasn't a helpful suggestion from Jeff to you. I.e. I was agreeing with you. :)
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #97 on: 17/08/2015 15:48:58 »
I cannot seem to "quote" you any more...

You said:

""This was an unfair suggestion by Jeff since he didn't defined his terms. The sigmas remind me of the Dirac notation but that comment doesn't bring anything to mind. It's not as if people readily remember everything from all fields unless they spend a great deal of time working with/studying that field.""

I said:

"I'm sorry, but I don't really think one has to spend a great deal of time studying a (edit: 'this') field to realise that a suggestion that questions the mathematical structure of Planks h constant, due to a possible factor of quantum time dilation actually relates only as far as Heisenberg's uncertainty principle, and that any investigation into calculating quantum probability is totally and utterly irrelevant and has no bearing whatsoever on the structure of Planck's h constant.

In fact 'one' of the the most logical approaches would be to study the Planck unit in relation to particle mass."

Hopefully that makes more sense now I've added what you said.

Hot chocolate with brandy is 'nice', I do it a lot when appropriate.  Sorry, I didn't mean to sound so sharp, yes you were agreeing with me in a 'sort of' fashion. :)
 

Offline timey

  • Neilep Level Member
  • ******
  • Posts: 1296
  • Thanked: 7 times
    • View Profile
    • Patreon
Re: How does light speed up when it exits a denser material?
« Reply #98 on: 18/08/2015 12:33:51 »
Look Jeff, you haven't responded, which surprises me because logically speaking it is your only move.  A move that, it may surprise you, would be received amenably by me.
I consider myself to be an emotional environmentalist and at least 'try' to take care not to leave my footsteps floating in someone's head.
I actually have quite a lot of respect for you in most instances.  When someone speaks to me here, (or I develop an interest), I make a point of reading a lot of their posts in order to get a measure of them.  (I read incredibly fast). Pete's statement, (which I would spend the considerable time locating to quote him were it not for the fact that I seem unable to quote Pete anymore,) ... however it stated "Jeff is quite a bright boy"... and I do feel this 'is' a valid statement.
I cordially invite you to perhaps pm me so that we can bury the hatchet. Nothing would give me greater pleasure than to put my 'little lawyer' back in my breast pocket and problems 'always' have solutions if one changes ones perspective.
 

Offline jeffreyH

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 3913
  • Thanked: 53 times
  • The graviton sucks
    • View Profile
Re: How does light speed up when it exits a denser material?
« Reply #99 on: 26/08/2015 18:30:03 »
Look Jeff, you haven't responded, which surprises me because logically speaking it is your only move.  A move that, it may surprise you, would be received amenably by me.
I consider myself to be an emotional environmentalist and at least 'try' to take care not to leave my footsteps floating in someone's head.
I actually have quite a lot of respect for you in most instances.  When someone speaks to me here, (or I develop an interest), I make a point of reading a lot of their posts in order to get a measure of them.  (I read incredibly fast). Pete's statement, (which I would spend the considerable time locating to quote him were it not for the fact that I seem unable to quote Pete anymore,) ... however it stated "Jeff is quite a bright boy"... and I do feel this 'is' a valid statement.
I cordially invite you to perhaps pm me so that we can bury the hatchet. Nothing would give me greater pleasure than to put my 'little lawyer' back in my breast pocket and problems 'always' have solutions if one changes ones perspective.

I have just read this last post but can't remember what the comment was that you wanted me to respond to. Can you post it here and I will try to respond and make sense. I am currently fixing system issues and working late so it might not be this evening.
 

The Naked Scientists Forum

Re: How does light speed up when it exits a denser material?
« Reply #99 on: 26/08/2015 18:30:03 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums