Does Electricity travel at the Speed of Light?

[cajen2]

Yeah, thanks, John.....though I'm none the wiser. So many explanations in physics defy common sense to me, so while I'm happy to accept them, I can never really internalise them fully. As I say, English grammar is much clearer to me....! 😆

[vlaiv]

11 minutes ago, cajen2 said:

Yeah, thanks, John.....though I'm none the wiser. So many explanations in physics defy common sense to me, so while I'm happy to accept them, I can never really internalise them fully. As I say, English grammar is much clearer to me....! 😆

Since you seem to be into languages - here is something that might help you grasp it a bit better.

You know how some phrases can't really be translated to other languages and can only be understood "in the spirit of the language"?

Physics is a bit like that - trying to translate something to common sense just fails - because they are two different languages. Some physics things you can only understand if you don't try to put them into common sense speak and just look at them in "science / physics" language.

Here is example - you seem to have a problem with photon having moment - that is because you associate momentum with moving mass as was thought in Newtonian mechanics and "easily associated with say - hitting a football and that same football smacking someone on the nose " kind of reasoning (age appropriate ).

You have a concept of mass being something solid - something that you can touch.

Thing is - nothing really touches there. When you sit at your chair - none of your atoms is really "touching" chairs atoms. It is EM force that repels you and photons are carriers of that force and they exchange momentum between you and chair - and that keeps you from falling thru the chair (if you look at sizes of nuclei and distances - it's mostly empty space and we should really just drop straight down thru the chair because of gravity).

All along - it has been photons. We just don't sense it that way so our common sense is based on this false image our senses present to us. Totally different language than the language of what is really happening.

[saac]

deleted - double post !

Edited January 30, 2022 by saac

[saac]

51 minutes ago, cajen2 said:

I think the problem I have with this is how a particle can have momentum without  mass....but physics was never my strong suit. 😉

If you want to know the difference between a gerund and a present participle, I'm your man! 😄

Exactly, it does seem contradictory.  Like all these things it's because we have only been told half of the truth !   Remember science is a series of reducing lies.  The momentum of an everyday object/particle is given by the relationship p = mv  - but this applies to the classical or Newtonian world.  It is not wrong, it works and holds true in our everyday macro world - it keeps aircraft in the air, nuclear power stations safe, planets orbiting stars.  The trouble comes when we try to apply it directly to the quantum world - it gives an incomplete picture of what is happening.  It turns out that the relationship between mass , energy and momentum is more correctly expressed as  p = ( E^2/c^2  - m^2c^2 )^0.5   .   The term m refers to the rest mass of the photon which of course is equal to 0 so that disappears from the equation leaving  p = E/c   .   Momentum of a quantum particle such as a photon then is related to its Energy only.   So I guess it is all in the definition of momentum  - our everyday  p = mv only tells a little of the story.

Jim

Edited January 30, 2022 by saac

[cajen2]

Thanks both. Rather as Terry Pratchett called education "Lies to children". 😉

[cajen2]

I remember my old physics teacher at the beginning of a new school year saying: "Remember all the things you learned last year? They aren't true!". I think it was at that point I decided that physics wasn't for me....

[saac]

1 minute ago, cajen2 said:

I remember my old physics teacher at the beginning of a new school year saying: "Remember all the things you learned last year? They aren't true!". I think it was at that point I decided that physics wasn't for me....

But is that not true of any subject.  Especially life  

"When I was a child, I talked like a child, I thought like a child, I reasoned like a child.  When I became a man I put the ways of childhood behind me."

Jim 

[cajen2]

Just now, saac said:

But is that not true of any subject.  Especially life  

"When I was a child, I talked like a child, I thought like a child, I reasoned like a child.  When I became a man I put the ways of childhood behind me."

Jim 

Not exactly. A gerund is always a gerund, a present participle is always a present participle and the date of the battle of Jutland is not debatable. Some subjects seem to avoid grey areas....😉

[cajen2]

Also, I trust you aren't implying that I reason like a child? 😉😄

[Zermelo]

1 hour ago, vlaiv said:

Some physics things you can only understand if you don't try to put them into common sense speak and just look at them in "science / physics" language.

 

1 hour ago, saac said:

The momentum of an everyday object/particle is given by the relationship p = mv  - but this applies to the classical or Newtonian world.  It is not wrong, it works and holds true in our everyday macro world - it keeps aircraft in the air, nuclear power stations safe, planets orbiting stars.  The trouble comes when we try to apply it directly to the quantum world - it gives an incomplete picture of what is happening.

 

"Make your theory as simple as possible, but no simpler." - Albert Einstein

"There could be no fairer destiny for any physical theory than that it should point the way to a more comprehensive theory in which it lives on as a limiting case."  - Albert Einstein

 

[Andy ES]

33 minutes ago, cajen2 said:

I remember my old physics teacher at the beginning of a new school year saying: "Remember all the things you learned last year? They aren't true!". I think it was at that point I decided that physics wasn't for me....

I had exactly the same at college , our lecturer said “this is how I’ve got to tell you how it is, but this is really how it is!”

I spent nearly 40 years generating and transmitting High Voltage electricity but never really understood what it was 😳

[saac]

12 minutes ago, cajen2 said:

Not exactly. A gerund is always a gerund, a present participle is always a present participle and the date of the battle of Jutland is not debatable. Some subjects seem to avoid grey areas....😉

But you would not introduce any of those definitions at the elementary stage of learning just as you would not teach deBroglie wave equation to all but the most senior classes. 

I suppose human defined subjects such as literature, music, art , history do benefit from a certain degree of  "absolutism"  .  There are no absolutes with science only shifting sands of understanding.  For me, that is what makes it so interesting, we get to see the secrets of the universe little by little - it is a story in which the ending has yet to be written. 

Here is a question for you. Image you have just read Macbeth (any other of Shakespeare's work)  , it is 1975.  Would your interpretation and analysis of the play then be the same as it would now?  Maybe there are no absolutes anywhere  

 

Jim 

[saac]

21 minutes ago, cajen2 said:

Also, I trust you aren't implying that I reason like a child? 😉😄

Absolutely not lol.    Hey, I see what you did there - science and literature  (written communication) both failing to provide the full answer  

Jim 

[cajen2]

As Tolkien said, "I've been suspicious of allegory ever since I was old enough to recognise it".

So literature, as you say, is all about interpretation. This, apart from being subjective, is also a product of society's norms at any given point in time. Some subjects just aren't about interpretation. What's the capital of Peru? Any debate?

What amuses me the most is that scientists constantly question things (great, so do I). But they're human, so will often say or hint that their current understanding is the correct one. After all, until only a generation ago, virtually all biologists accepted evolution as a constant linear process and all cosmologists accepted the steady state theory.

I often wonder when the next paradigm shift will be, and people who accepted dark matter and energy as a fact are laughed at!😆

Edited January 30, 2022 by cajen2

[wulfrun]

10 minutes ago, cajen2 said:

Some subjects just aren't about interpretation. What's the capital of Peru? Any debate?

Not at present but any capital city can be changed, in name or location (or both).

Peru hasn't always had its present boundaries and been called Peru either.

[cajen2]

Just now, wulfrun said:

Not at present but any capital city can be changed, in name or location (or both).

Peru hasn't always had its present boundaries and been called Peru either.

Absolutely right, but even then, any debatable areas are very rare, short lived and soon accepted by all.

[cajen2]

If you prefer a different example, try Singapore. Since independence, the capital is (and quite probably will always be) Singapore city, since there are no other large cities there! I suppose they could build a new capital ( like Brazil did) but, believe me, there isn't much room in Singapore for that!

[cajen2]

A germane quote from Robin Williamson which laughs at both our positions: "All your so-hard facts painted thinly on the void....why were you not more pleasantly employed?" 

 

[saac]

43 minutes ago, cajen2 said:

As Tolkien said, "I've been suspicious of allegory ever since I was old enough to recognise it".

So literature, as you say, is all about interpretation. This, apart from being subjective, is also a product of society's norms at any given point in time. Some subjects just aren't about interpretation. What's the capital of Peru? Any debate?

What amuses me the most is that scientists constantly question things (great, so do I). But they're human, so will often say or hint that their current understanding is the correct one. After all, until only a generation ago, virtually all biologists accepted evolution as a constant linear process and all cosmologists accepted the steady state theory.

I often wonder when the next paradigm shift will be, and people who accepted dark matter and energy as a fact are laughed at!😆

Yes but the capital of Peru is not known to the universe (the subject of science) , it does not care, and while it may be Lima today, it may change in 10, 20 , 100 years. Funny, I've been planning my summer holidays now that restrictions have lifted a little. I fancied seeing Constantinople, I had read so much about it in books.  To my surprise though it no longer exists , looks like it has fallen off the face of the map     Hey surely grammar is not absolute either, it too much change.  What about the definition of gerunds and all, have these not evolved to reflect the way we are now?

I think to the outsider science does come across as an arrogant subject full of certainty in itself. Paradoxically the only certainty in science is uncertainty  - which we love to measure    The only thing any scientist can honestly say about a theory is that it reflects the best interpretation of nature/universe at that moment in time.  Even the sainted Newton has been surpassed,  but whisper that in hushed tones, we don't want to cause panic. 

Jim 

Edited January 30, 2022 by saac

[saac]

5 minutes ago, cajen2 said:

A germane quote from Robin Williamson which laughs at both our positions: "All your so-hard facts painted thinly on the void....why were you not more pleasantly employed?" 

 

I like that.  I've often thought what if we could discuss matters with the good and the great that have since past on.  Would Einstein,  Newton, Shakespeare, Beethoven be anxious to find out about what has progressed in their respective fields, would they still be eager to push back the boundaries .  I think they would have laid all of that passion down and would be more interested in the more human experience; going for a walk, a nice meal, conversation with friends.  It does make me wonder why we get so passionate about some things and not pay more attention to others that matter more. 

Jim 

[cajen2]

RW is a poet and songwriter. The opening of the song from which that quote comes is "You may have observed, when you walk into a wall, you get a certain sensation of reality...." He is also a bard and raconteur and a very wise man

 

[cajen2]

BTW, the date of the Battle of Jutland is still fixed.....😉

[saac]

13 minutes ago, cajen2 said:

BTW, the date of the Battle of Jutland is still fixed.....😉

You wait until the revisionists get around to it ,  1916 AD will change to 1916 Common Era  

Jim 

[Kev M]

23 minutes ago, cajen2 said:

BTW, the date of the Battle of Jutland is still fixed.....😉

Surely it would be dependant upon the speed of the observer .....🙃

[cajen2]

The next time I'm travelling at 90% of the speed of light, I'll let you know....😄

Mind you, I'll have put on a lot of weight!