Physics question

[root]

I think I have a definitive answer now.

and that answer is no.

the answer is, (I believe) like I said earlier, you don't move the lattice of connected molcecules, you send a wave up the stick.

I'm going to say it's the difference between the speed of electricity/the speed of electrons moving in a wire, and the speed of communication using electricity.

 

[connchri]

Berry120,

1st of, my sincerest appologies for coming across as a bit of a prat. It was a poor reaction to your reply to my post - I was being overly sensitive and took it a bit offensive.

That aside, the other experiment you refer to, I haven't had the privilage to read so I couldn't comment, but my gut instinct would be that it is another case of the results from the experiment being taken out of context.

One other thing to bare in mind, is that even if you could transmit data at FTL speeds, what use would it be? as the receiver would receive the information before it was sent (if you take into account that the sender and reciever would be in different time frames from each other depending on the distance from each other - relativity). The reciever would need to be giving advanced warning of transmition, that could only happen at a maximum speed of c, and then that leads on to other problems such as paradoxes. It's a bit bambozling, but if it was proven possible, I'd still not see the point.

Imagine a sender sending information faster than light to a reciever 3 minutes away in time (3 light minutes in distance), but the receiver gets that information instantenously. Now what if, upon receiving that information, the reciever sends it back instantanously to the original sender, who is still 3 light minutes away and tells him not to send the original information? The original sender would receive this second signal 3 minutes before he actually sent the original one. It's a paradox, it couldn't happen. Why would the second signal be sent if the 1st was never sent? But then, why would 1st one not be sent unless the original sender was told not send it by the second signal? But then why would this happen if the 1st signal was never sent? but then, but then, but then.............. This is my understanding of what would happen. I could be wrong though.

I haven't came accross a single, truthful, report of any information having been transmitted at FTL speeds. Call me a cynic, but as physics is understood today, it is not possible.

Don't get me wrong, I am of the opinion that even todays 'cutting edge' physics will give way to deeper and brighter idea's in the future. One famous physicist (I can't recall their name, maybe Maxwell??) stated that all of the laws of physics was known - only for relativity and QM to rubbish that overnight. Perhaps this will happen again.

I don't think that the wave/particle duality of photons was the reason for QM, but more of an accumulation of a number certain phenomonon that couldn't be explained classically. It was Einstein with his explination of the photo-electric effect and his idea of discrete energy levels/packets ("quanta" - hence Quantum Mechanics) within electron orbits that seriously got the ball rolling into QM. It was this that he got the Nobel prize for and not for relativity as many incorrectly assume (mainly because relativity wasn't a clean idea that physicists at the time wanted to embrace). QM was even too weird for him, so much so that he didn't even embrace it fully. It took a lot of work from more physicists to prove the theories he came up with but which he didn't fully accept.

Anyway, I'd love for FTL travel and communication, but our current understanding of physics, still, forbids it. Perhaps once Zephram Cochrane is born into the world and James T Kirk is blasting Klingons back to their premordial soup, then it'll change. Until then, I'm still one of the biggest cynics out there.

CW.

 

[sniperviper21]

nothing is impossible, remember that...


in the 1920's no one thought you could go faster then the speed of sound either.

 

[berry120]

1st of, my sincerest appologies for coming across as a bit of a prat. It was a poor reaction to your reply to my post - I was being overly sensitive and took it a bit offensive.

No worries, we've all had those sorts of tendencies, myself included. My comment about you reading my post was a genuine one (I often miss the last post for cross posting reasons and so on) rather than sarcy, but reading it back it's not brilliantly clear!


I'm still not 100% convinced it's entirely impossible, but I will take the stance that for the frames of reference reason it's not possible to send information faster than light using my initial example. Of course you're right - there hasn't been a single proven example of definite FTL, I just think that some of the experiments people have done have pointed towards the fact it might not be as impossible as some first think.

But heck, when we start to get to this level of physics nothing's certain, and every man and his dog seems to have a different explanation of the things that can't be explained by classical physics these days. Some even claim that the speed of light isn't constant, which would of course have a knock on effect of all the other constants out there, which in turn would throw almost all of our existing theories out of line!

From a more general perspective, I think we've got it majorly wrong as a whole somewhere. Not anywhere in particular that I can name, but the whole weirdness of the quantum world just seems a tad too weird to me. Much like when the earth was "definitely" flat and at the centre of the universe we had all sorts of theories flying around explaining why the stars weren't appearing to move as they should if this was the case, and all sorts of other intricacies explaining eclipses and the seasons...

I wonder sometimes if this is similar and there's something we're taking completely for granted as absolute fact, that in the real world just isn't true. Just speculation of course, but who knows!

 

[root]

Imagine a sender sending information faster than light to a reciever 3 minutes away in time (3 light minutes in distance), but the receiver gets that information instantenously. Now what if, upon receiving that information, the reciever sends it back instantanously to the original sender, who is still 3 light minutes away and tells him not to send the original information? The original sender would receive this second signal 3 minutes before he actually sent the original one. It's a paradox, it couldn't happen. Why would the second signal be sent if the 1st was never sent? But then, why would 1st one not be sent unless the original sender was told not send it by the second signal? But then why would this happen if the 1st signal was never sent? but then, but then, but then.............. This is my understanding of what would happen. I could be wrong though.

I think that you've gotten mighty confused somewhere.

you're suggesting that if you could send a signal faster than light that it'd arrive in the past?

so if you're communicating over a distance of 3 light minutes, then the person receiving the message 3 minutes into the past? then they reply, and you get the reply 3 minutes before they sent the reply. -i.e 6 minutes before you sent the message.

it's just simply not true. the earth and the moon exist in the same time just different places, and different places aren't in different times... the earth is not three minutes behind the moon, and the moon is not three minutes behind the earth, (nor is it the second or so behind or in front than it takes for light to reach here from the moon).

the earth and the moon exist at the same time.

what actually happens is the view of the earth that you have from the moon is actually three minutes into the past, and the view of the moon that you have from the earth is three minutes into the past. (well, a second -just over).

when you look at an object a distance away, you don't see the object you see a reflection of the light, and you see that light when it reaches you.

basically if you were three light minutes away from the earth and you saw an alien land, you could send a message faster than light, (instantaneous if you like), but your message will be being sent three minute after the even has happened. because that's how long it took for the light to reach you.

looking at a distant object only tells you what the object looked like at the time the light was reflected off of that object.

Kind of like you're looking into the past.


so if I send a message to a place 3 light minutes away saying wave a red flag, they will get that message, wave a flag instantly, but it'll still be three minutes until I see the flag waving...

if I send a message saying wave a red flag, they wave a flag and send a message to say OK, then I could send another message to say I can't see the flag, because I can't, I won't see it for the three minutes it takes for the light to get to me.

I could send a message saying wave a flag.
they do, and send back message saying that they are waving a flag, though I can't see it because the light hasn't reached me yet. then I see the flag and say take it down. they do take it down, but I can still see if for three minutes, because that's the time it's taken for the light to get to me, removing the source of the reflected light isn't going to interrupt the photons that are already travelling my way.

if I wanted to see the flag for 1 minutes only I 'd need to send a message saying wave a flag, then a minute later send a message saying remove the flag, 3 minute after message 1, (and 2 minutes after message 2) I'd see a flag, a minute after (4 minutes after message 1 and three minutes after message 2).

basically, if I wanted to seethe flag for only a minute I'd have to tell them to remove the flag, before i'd even see it, this wouldn't be a paradox.

at least no more of a paradox than it is to see lightening and hear thunder seconds afterwards. it's just because one method of transmission would be faster than another.

I could no more ask for a flag not to be seen after it's been put up three light minutes away, by sending a take down message before I actually see it). than I could see lightening and try to prevent the thunder, I can't prevent it because it's already happened. just the physical phenomenon hasn't reached me yet due to the transmission time of sound being slower than light.

 

[J03]

nothing is impossible, remember that...


in the 1920's no one thought you could go faster then the speed of sound either.

Maybe, but you wouldn't answer "yes" to every question just because "nothing is impossible", would you?

I asked my physics teacher about this question today. She said something about Photon's being Electromagnetic Force carriers, and that atom's held together by electromagnetic forces - So bond's between atom's consist of Photon's.

I cant remeber the rest. She wrote it down on a piece of paper, but I forgot it at school. You've probably all been through this, anyway.