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Electromagnetic Signals Exceeding Light Speed?

intaglio, you sound like me when I was at school - I remember having this stand up argument with a teacher because he claimed that an 11 sided shape was called an elevenogon. I recall being very angry that he was misinforming people and that he couldn't even be bothered to look in a dictionary to ammend his mistake. BTW its a hendecagon :rolleyes: I think he called a 7 sided shape a septagon as well which also wound me up. bah!

Always was a smartass....
 
Teachers really don't like being told they are wrong do they? I also don't like never really being told in school what atoms were like. They also talked about the planet model, instead of wave stuff.
 
again I had exactly the same problem, X. I called my chemistry teacher over during one GCSE lesson (that's O level, junior high level - ie pre 16) and said 'if the model that we got taught before was wrong, and now your telling us that it's different, how do I know that it won't change when I do A levels, or degree' to which he responded by telling me that most of what we were taught up to degree level was baloney and the model of the atom was still highly theoretical. I can understand the necessity for simple models when your learning, but I disagree with the way it's presented as fact.

I tend to work things out from first principles most of the time, so if I know how valency, orbitals etc work I can predict what behaviour a certain element will have and also how it will react with other chemicals. Without this fundament to work from I find it harder to learn by rote or with mnemonics.
 
dot23 said:
afebk - what did you find disappointing ijn both systems - it'd be interesting to hear from someone who's seen both sides of the argument about higher education. An American university lecturer I met recently agreed with me that the sponsorship system (especially with sports) had lead the system into disrepute and should be scaled down if not removed - do you agree?

I'm not sure what you mean by 'sponsorship' position, but there is way too much emphasis on sports here. (Actually, I think there is too much emphasis on sports the world round, but then again, I am somewhat of a facist--I really don't think that schools and universities should sponsor organized sports teams.) I have a long list of criticisms, but in general, I'd say that the American system needs better vocational training in the high schools, and that we need much higher standards for admission in most state-run university systems. When I was at Leeds, I found the courses lacking in rigo(u)r. I was used to a great deal more work. I have to point out here that I did my BA at an exclusive private women's college, so my experience was not typical in that respect. Also, the lack of interdisciplinary and liberal arts programs was alarming. Leeds and the University of Glasgow were the only two universities that would let me take classes in studio art, art history, and chemistry. Even then, Leeds would only let me take first-year level chemistry courses, even though I had already taken higher level courses.

That's not what this thread is about, is it?
I did think that museum's report was odd, since all of the trekkies I know are quite intelligent, and some are even physicists. Anyway, Star Trek is not about science, it is about ethics, isn't it?
 
afebk said:
. . . Anyway, Star Trek is not about science, it is about ethics, isn't it?
I didnt'know it was about an English county (sorry very bad english pun)

The Brits do love to compartmentalise things. If you're interested in science you can't be interested in art or law or business. Stupid.
 
Star Trek is as any good science fiction not about technology. People who think it is all about coming up with cool inventions have gotten it wrong.
 
Intaglio - you are totally correct when stating that when viewing the world throught General Relativistic spectacles, greater than c. travel = faster than light. However, given the available vacuum energy, QM allows FTL transmittion of anything, including human beings (the chance is so small as to be almost negligible - but not quite!). Once we allow this, and I assure you it is possible, the only way to reconcile events is with Everett-Wheeler theorem which predicts an infinite branching of Universes with every quantum measurement (as you may well know, if it is not measured, the state does not exist). The possibility of this happening is miniscule, but not zero, which is why we still watch Football rather than the Unified Field Theory Channel (well played to the Patriots, BTW!!!)
 
Thats why I said our Albert is showing holes Anton (pun intended). :D

I like Everett-Wheeler, but the alternates are not infinite. Its a BIG number but not infinite. Isn't it something like
(no. of particles after big bang)^(no. of quantum states)^(no. of time quanta to present) I could have got that in the wrong order but you know what I mean.

(For those who don't know ^ is "to the power of")
 
Hello There.
There is another way to reconcile everything and that is that EVERYTHING is fixed and preordained and we have no free will, everthing we ever measured was; as is: and will be. Free will is an illusion and we are, and every particle, all but bit players on some elaborate movie called reality.
 
Scientists usually expect that I think. But it doesn't explain much anyway.
 
This update to the science seems to be just retelling the original post upthread mostly.
Is this 'new science' or a rehash?

Physicists Have Broken The Speed of Light With Pulses Inside Hot Plasma
"....To break the hearts of those hoping it'll fly us to Proxima Centauri and back in time for tea, this superluminal travel is well within the laws of physics. Sorry."
https://www.sciencealert.com/pulses...-speed-limit-and-it-s-been-seen-inside-plasma
 
This update to the science seems to be just retelling the original post upthread mostly.
Is this 'new science' or a rehash?

Physicists Have Broken The Speed of Light With Pulses Inside Hot Plasma
"....To break the hearts of those hoping it'll fly us to Proxima Centauri and back in time for tea, this superluminal travel is well within the laws of physics. Sorry."
https://www.sciencealert.com/pulses...-speed-limit-and-it-s-been-seen-inside-plasma
They better fix it quick :p
 
They're going to fix it using milk.
Pasteurised before you see it.
 
This update to the science seems to be just retelling the original post upthread mostly.
Is this 'new science' or a rehash?

Physicists Have Broken The Speed of Light With Pulses Inside Hot Plasma
"....To break the hearts of those hoping it'll fly us to Proxima Centauri and back in time for tea, this superluminal travel is well within the laws of physics. Sorry."
https://www.sciencealert.com/pulses...-speed-limit-and-it-s-been-seen-inside-plasma
Exceeding the speed of light in some specific medium is not news. However, this latest article is claiming to report the first time it's been done within a plasma. The original report that started this thread was referring to exceeding the speed of light in wires.
 
Some of the older conversation on this thread has me thinking; I hope someone out there can help me understand these things better.

As I understand it "the speed of light" as a synonym for c is not very precise. As has been mentioned, light does travel at different speeds depending on the medium. In fact, since there is no such thing as a perfect vacuum, even "the speed of light in a vacuum" is a theoretical concept that doesn't quite exist in the real world. So when we say objects or information can't travel faster than the speed of light, or that light travels at the same speed for all observers (leaving aside for a moment whether those are true statements) what we are actually referring to is that abstract velocity labeled "c", not the actual speed of light.

This is not to say that the speed at which light, or other things electromagnetic, travels is unrelated to c - in fact they are intrinsically related. It's just that the speed at which light travels is because of the nature of the constant c, not identical to it.

Am I getting this more or less right?
 
Cah!
Where's a relativistic physicist when you need one?
 
I remember (ah! the smell of madelaines) when I was about 7 I broke my pencil and being a lazy child couldnt be bothered to go to the pencil sharpener so I was chewing it sharp. The teacher came up behind me and told me not to do that because I'd "get lead poisoning". When I turned round and told her it was not lead in the pencil but graphite and clay she became quite annoyed and gave me *lines* for talking back. I think it was later in the same year when they said that Mary was a virgin and I popped up with "but she couldn't have been, she got pregnant and had a child".

I must have been the most obnoxious brat!
Got the same sort of bollix from a teacher when I was about nine. She'd been talking about the birth of Jesus being the dividing line between BC and AD, therefore by the unbroken count from His birth it was now 1969 or 1970 or 1971 or whatever it was, and how long a time it is by our standards.. Now, I'd been independently reading - I guess this is the sort of thing teachers dread - and I started asking about, well, are we sure? Because the Ancient Romans didn't count years as we do, Miss, they used the number of years an Emperor had been reigning, and there are people who think we got the count wrong when we switched over, so that Jesus was actually born in what we'd call 4 BC, so isn't this year really 1965 if we correct the mistake?
so all the other kids sniggered, who is this idiot who believes Jesus was born in 4 BC, Teacher gets angry but can't easily correct me, I think she fell back on "Because the Bible tells us so", and I said "What if the Bible's wrong?" - dead silence, shocked gasps, me in trouble. Took a while to think it through, but I never trusted a teacher to get it right again, after that.

Oh, and much later, discovered the census that gets mentioned in the Gospels which my teacher was using to time Jesus' birth to 0 BC... is most likely to have happened sometime around 6BC. therefore.... it's really 2015, guys. 2020 is yet to happen...
 
Got the same sort of bollix from a teacher when I was about nine. She'd been talking about the birth of Jesus being the dividing line between BC and AD, therefore by the unbroken count from His birth it was now 1969 or 1970 or 1971 or whatever it was, and how long a time it is by our standards.. Now, I'd been independently reading - I guess this is the sort of thing teachers dread - and I started asking about, well, are we sure? Because the Ancient Romans didn't count years as we do, Miss, they used the number of years an Emperor had been reigning, and there are people who think we got the count wrong when we switched over, so that Jesus was actually born in what we'd call 4 BC, so isn't this year really 1965 if we correct the mistake?
so all the other kids sniggered, who is this idiot who believes Jesus was born in 4 BC, Teacher gets angry but can't easily correct me, I think she fell back on "Because the Bible tells us so", and I said "What if the Bible's wrong?" - dead silence, shocked gasps, me in trouble. Took a while to think it through, but I never trusted a teacher to get it right again, after that.

Oh, and much later, discovered the census that gets mentioned in the Gospels which my teacher was using to time Jesus' birth to 0 BC... is most likely to have happened sometime around 6BC. therefore.... it's really 2015, guys. 2020 is yet to happen...
Also any census at the time would have been carried out in or around june not december so we are at least 6 months out whatever.
 
So when we say objects or information can't travel faster than the speed of light, or that light travels at the same speed for all observers (leaving aside for a moment whether those are true statements) what we are actually referring to is that abstract velocity labeled "c", not the actual speed of light.
That's right. The constant we call 'c' is really the speed of information; usable information can't travel faster than the speed 'c', and light travels a tiny bit slower than that (in practice).

In reality the speed of light through the near-vacuum of space is so close to the speed 'c' that we can't measure the difference. Any difference would be made entirely irrelevant by the expansion of the universe, which is a very significant effect. The oldest stars we can see were about 40 million light years away when they started shining, and the light they emitted then has taken 13 billion years to get here, because of expansion. Those same stars, if they still exist, are 46 billion light years away by now, and travelling away from us at a speed much faster than light.

Confused?
 
Imagine this.
I am standing on one side of a wall, and my colleague is standing on the other side of the wall.
The only means of communicating with each other that we have is a small hole in the wall, through which a metal road passes, with no gap around the sides.
This metal rod can slide freely through the hole in one single movement, so can be used to communicate in binary (in or out would be 0 or 1).
This movement of the rod would be instantaneous, in that as one end is moved the other end moves at the same time, so the communication would be without any lag.
Now imagine that metal rod is thousands of miles long and can move just as easily.
As one end is pushed in, regardless of the length of the metal rod, the other end moves out, so would that allow information to travel faster than light, if the length of the metal rod is longer than the distance light would travel in the time it takes to move the rod?
 
This 'superluminal rigid rod' idea has been examined in the past, and it can't be used to send FTL messages, unfortunately. By pushing on the rod at one end you are sending a pulse of compression along the rod, and this pulse will travel at the speed of light (or less). No physical material is perfectly incompressible.
 
Quite eloquently put, eburacum. While the rod makes for an interesting thought experiment, the fact that no physical substance is truly inelastic makes it irrelevant in the real world. Consider that a rod that would (theoretically) beat out the speed of light by two seconds would have to be much longer than the distance to the moon. There ain't nothin' that rigid.
 
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