[Q] How would instant communication change what we know about the universe?

[Moontanman]

Well in that case I guess that no matter how counter intuitive it is it's really not the same instant everywhere no matter how fast you can see that instant. Oh oh oh, but why is copper red? Yeah, explain that one dude :hihi:

[modest]

Copper... red? :hihi:

 

Humm.... Perhaps the roman god Mars had something to do with it. No... wait... I think we're safest evoking quantum mechanics. Copper isn't exactly red, it just has a higher probability of being red than not being red :blahblahblah:

 

I'm not being very convincing am I :doh: Ok, let's make this sound a bit more scientific...

 

I think the 3d, 4s transition energy is small-enough to coincide with visible light in copper (much like gold). Copper is kind of special in its electron configuration and position on the periodic table because 3d electrons have more energy than 4s electrons in elements lighter than copper while 4s has more energy in elements heavier than copper. This has to do with the different quantum numbers n and l (lowercase L). A larger value n and a larger value l both mean more energy for an electron, but which is the dominant factor depends on if the element is greater or less than copper in atomic number.

 

This is not a relativistic effect, as with gold and cesium.

 

Ok... that's my final answer Regis, and I'm stickin' to it :)

 

~modest

[CraigD]

If someone came up with a way to detect an event instantaneously how would this change our way of thinking about the universe?

 

Would it just mean we could get information about a distant supernova the instant it happened instead of having to wait several years or would it have a more fundamental meaning about the universe?

Ignoring the possibility of impossibility of instantaneous signaling, I think the answer is “it would have a more fundamental meaning about the universe”. In short, it would make the universe sometimes acausal, which is to say, effects could precede their causes. Actually, any signaling faster than the speed of light in vacuum, not just “infinitely fast” instantaneous signaling, would have the same implications.

I guess I need it explained to me in baby steps. How would me seeing a nova 1000 light years away the instant it happened be communication with the past?

It’s easier, I think, to cast a thought experiment in terms of ordinary communication than observing supernovae.

 

Lets say we have a pair of device that send text messages between one another, similar to an ordinary handheld game (Nintendo DS, etc.), but rather than sending their messages via radio waves over short distances at slightly less the c, they send them instantaneously over astronomical distances. Further, lets say we either employ someone to reply to any message received on the phone with the same text it receives, or more plausibly, run a simple “echo back” application to do this.

 

Now let’s assume that one device, the sender, is on Earth, and the other, the echoback device, is on the Voyager 1 space probe, about [math]1.6 \times 10^{13} \,\mbox{m} \dot= 54000 [/math] lightseconds away, with speed relative to one another of about [math]25000 \,\mbox{m/s} \dot= 0.000156 \,\mbox{c}[/math]

 

Let’s say you’re playing some sort of wheel of fortune game (roulette, etc). Upon seeing the winning number of each play, you text it to the echoback device, which texts it back to you. However, according to special relativity, the reply will not arrive back at your device nearly instantly, but about [math](54000+0.000156)\cdot0.000156 \dot= 8.46[/math] seconds before you sent it! (see attached image for diagram)

 

Assuming the game is unusually fast (I’m pretty sure you can’t place a bet on a roulette wheel less than 8 seconds before it finishes its spin), you could use this to always place a winning bet. Or, you could include in your text message not only the winning number, but whether you played, and then contradict yourself, in which case your message would indicate you did not play, in which case you would, in which case ... a sort of grandfather paradox occurs, giving rise to a compelling need to change your way of thinking about the universe!

 

Note that, as noted above, the signal need not be instantaneous for such a paradox to appear, only faster than c.

 

PS: If there are no objections, I'll move this thread to the physics and math forum, as it seems to be more of a discussion of modern physics than simple Q & A.