# Light speed internet

1. Sep 17, 2010

### NetMage

Hello, I know I'm just full of silly ideas, but afterall this is the physics forums, and I happen to have lots of questions :P. So, basically what I'm interested in, as the topic suggests, light speed internet. Now now, I know many of you would respond with, "its been done --fiber optics!!". However, what about sending information on light waves rather than through fibers? What setbacks has there been? Does it all come down to when observed the wave collapses thus distorting the information?? Or have we simply not figured out how to modulize the information? I looked through here and a few other places before posting, but there were really no informative answers.

2. Sep 17, 2010

### DrChinese

Microwave transmission towers - as well as satellites and fiber optics - are all examples of light (photons) used for signaling applications. It goes at c (actually a bit less).

3. Sep 17, 2010

### Dr Lots-o'watts

It's the same thing. Fibers act as a guides ("roads") for modulated light waves.

4. Sep 18, 2010

### NetMage

Hm, interesting. So would quantum computers be the answer to ridding lag or delays? It seems that satellite has about a 6 second delay due to it having to ping so many places, but I know for a fact that if it takes light from the sun ~8 min to reach the earth...that even if 'light speed waves' were traveling 6 different places, it should not take 6 seconds considering the distance being covered is far less than that of the sun. I can infer from this though that it must have something to do with the time it takes the computers to modulize and demod the information being sent. Would quantum computers have any impact on this problem?

5. Sep 18, 2010

### Faxmachinen

Don't forget that ping measures the total time it takes both ways, and that the satellite isn't an ISP. Thus you get a predicted ideal ping equal to four times the distance to the satellite[1] divided by the speed of light. I calculate this to be approximately 479ms. And that is if you're directly beneath the satellite, and your ISP is next door.

[1] http://www.suite101.com/content/geosynchronous-satellite-orbits-a48472"

Last edited by a moderator: Apr 25, 2017
6. Sep 18, 2010

### timetravel_0

NetMage, I think your missing the point of light(fiber optics) as a medium for data communications. Data is only transferred in small chunks called packets. From your PC a packets are sent to the modem which are then clustered into a larger packet, sent to a router on the ISPs network which is then clustered with other packets from other people on the network, which is then sent to another point clustered and so - eventually the packets are reduced back down once they reach the destination and then broken down by the modem of the server your trying to reach. These packets are sent at a specific rate. Higher rates need higher bandwidth.

What makes fiber optics a better medium is the way data is transmitted vs. in cable. Cable uses electricity where digital information is modulated into a wave and transmitted through the cable signal. The bandwidth for this technology is limited to the frequency of the modulated wave. Cable also has a limit on distance that data transmission is reliable, so this technology is limited. However, fiber uses light and it doesn't transmit data by modulated waves, but rather pulsating light. This means the only limit on bandwidth for a single fiber is the width of a photon - that would be very very very high speeds! However, computers can't even process or send data at that speed. Currently, fiber optics has yet to dominate over cable - in most situations fiber is converted down to cable, or phone line(DSL, and dial-up) and then is transmitted into your home - thus limiting the fiber technology even more. Currently fiber can transmit 320Gb/s(GigaBITS/Sec - that's 327680Mb/s!) which most homes getting cable only getting up to 12 - 25Mb/s and DSL is limited to about 1-12Mbs.

I'm sure quantum computers will revolutionize the internet once they are built and used worldwide. Just as Dial-up limited us to simple HTML web pages and corny MIDI music, Fiber brought about bandwidth intensive AJAX Technologies, and Video & Music Streaming. There are experiments where scientist have slowed light using Boseâ€“Einstein condensates - which if used with current computer technology, we can transmit data in pulses down to the size of a photon and then send it out at the speed of light - allowing HUGE chunks of data Billions of Billions of Billions of Gigabytes - in an instant.(This could be an exaggeration... + or - some...haha) Technology then too would take a shift as we developed computers that can think like humans, that can make logical and emotional choices for us, what can think for us like a second mind. Searching the internet will be transformed from "Recipe for Bread" to "Will my aunt Susan like Wheat bread or White?" and the computers will be so smart they will know your aunt Susan better than you. Crazy, I know... but possible.

7. Sep 19, 2010

### Dr Lots-o'watts

I'm not up-to-date on the possibilities of quantum computing, but you may want to read on optical computing. The concept is to replace electronic components of computers by optical equivalents. I personally had the opportunity to do research on all-optical switching, but to my knowledge, an all-optical computer has yet to be constructed.

Here's a starter: http://en.wikipedia.org/wiki/Photonic_computer

8. Sep 19, 2010

### NetMage

Truley fascinating. So can any1 explain in detail what quantum computing really is? At the moment I have pretty limited knowledge on the subject as I have not taken the class yet =/ my physics is limited to calc-based Newtonian physics and what I've read in my free time.

9. Sep 19, 2010

### timetravel_0

Quantum Computing will take advantage of quantum phenomena such as superposition and entanglement. The bit operation will be different that standard computing which is binary - on or off, 1s and 0s. Instead they will use the properties of the particle to describe data - giving them a wider range. Lets assume they can measure 8 different properties of a particle - that means they can move from binary to hex. In programming, each character is represented in a hex code. 00, 01, 02... A1, A2, A3... CD, CE, CF... and so on to FF. The programming language looks like:

x = \$_POST["UserMessage"];
If(x = "Hello World") {
}

Which is then converted into Hex and looks something like:

AF FC 04 42 CD D8 78 DC 00 05 CC
CD 54 02 13 5D FC 04 42 54 02 55

The Hex Code in memory is represented not as Hex, but as Binary - so the code is then lengthened to:

0000 1111 1111 0011 0000 0010 0010 0001
0010 0001 0011 0100 0110 0101 0011 0000
0110 0010 0011 0000 0010 1010 0000 1111
0000 1111 1111 0011 0000 0010 0010 0001
0010 0001 0011 0100 0110 0101 0011 0000
0110 0010 0011 0000 0010 1010 0000 1111
0000 1111 1111 0011 0000 0010 0010 0001
0010 0001 0011 0100 0110 0101 0011 0000
0110 0010 0011 0000 0010 1010 0000 1111

and so on.... Well with Quantum Computers - the code isn't transmitted in binary but rather hex(or something else.. don't know that much), making the bit much smaller - which is called a qubit(quantum bit). Smaller bits, more data within a given bandwidth. More Data means faster processing. Right now, data processing is limited to the size of an electron - with gaps in between, in the future with quantum computers - they are only limited to the number of combinations of properties for which a particle can be measured plus the side of the particle - which will have no gaps since it measures properties and not "heartbeats" pushing the electrons even closers... giving it a HUGE leap in processing power. The bit operation of quantum computer can be a bit more complex - so my example is only to understand it in a simple way.

Take the class, it will make more since of it.

10. Sep 19, 2010

### NetMage

Yea I take QM I next semester, am very excited! As well as contemporary physics. Of your knowledge, do you know what universities or whom might be doing big research on quantum computers?

11. Sep 19, 2010

### Danger

And just where the hell have you been hiding, young man? I honest-to-**** thought that you'd bought the biscuit or at least retired. Nice to have you back.

12. Sep 19, 2010

### timetravel_0

http://ctp.lns.mit.edu/research-quantum.html" [Broken] to name a couple. I am sure most universities have quantum computing research centers since it is the up and comming technology. They are striving to perfect munipulation of the property of an electron without disrupting other electons - as well as methods for storing and transfering the data... It will be very complex...

If your interested in quantum mechanics I suggest you watch this video series on youtube called http://www.youtube.com/watch?v=bw5TE5o7JtE". It is a 15 video series and its quite interesting - its covers the basic principles of Particle Physics, Forces, The Standard Model, QM, and QED(Quantum Electro-Dynamics). Good Luck.

Last edited by a moderator: May 4, 2017
13. Sep 19, 2010

### NetMage

Thank you, you've been quite helpful :) . And thanks again to the rest of you PF!

14. Sep 19, 2010

### Drakkith

Staff Emeritus
Interesting. I never realized how quantum computers worked. I've looked it up on wikipedia a few times, but trying to get all that into my head and understandable gives me a headache lol. So pretty much, the advantage of quantum computing is that instead of only 2 states to use, we can use more?

15. Sep 19, 2010

### Staff: Mentor

No, these are completely separate issues.
6 seconds would be an awful lot. Geostationary satellites are at something like 22,000 miles, which means they add about half a second to a ping (with 4 trips, as pointed out above).
No, that is done extremely quickly - miliseconds - it is not an issue at all.

16. Sep 20, 2010

### Staff: Mentor

If you take "light" literally, you don't have a reliable transmission. Rain, birds, fog - whatever you put between transmitter and receiver, it can get blocked any time.

But it has been done on many occasions, a friend of mine designed a "light phone" back in seventies, IIRC he planned to use a LED and a telescope for transmission. These were pre-digital times, and it was not easy to get a phone line in Poland. Not sure if he finally built a prototype or not.

17. Sep 20, 2010

### timetravel_0

Well I had an entire post typed up to explain this and I pressed the backspace key when the text box was not in focus - and the browser backed me up a page.... and i lost everything i typed... stupid IE....

Anyway. Yes, and no. A normal computer doesn't measure states - it reads pulses. Pulses of electrons(thousands or even millions of them) to represent a 1(on) or a 0(off). A quantum computer will measure the probability of the state of a single electron. I've done a bit more research on this and I THINK I get what its doing. An 8 qubit system - represented by 23 will use 3 binary digits represented by a(000), b(001), c(010), d(011), e(100), f(101), g(110), and h(111). Each binary digit represents the probability that the electron is pointing up(1), or the probability that it is pointing down(0). I THINK this is what it is saying... I could be wrong.

Basically it is measuring different states of an electron... 8 different states for a 23 qubit system.... 16 for a 24. Take for example the way computers process characters. A character is represented by a number - for instance Z is = 90. How do I know this... well I'm an ex programmer... but you can hold down the Alt key and type 90 on the number pad and get the letter Z when typing in a textbox or notepad. Whole numbers are not processed - but rather HEX (0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F). 90 in HEX is 5A - why? Because if you were to count in sequence to 5A you would have counted 90 different numbers. Hex gives the ability to store up to 256 different numbers into two digits. Hex is then processed by the computer in Binary, 1s and 0s. 0000 = 0, 0001 = 1, 0010 = 2, 0011 = 3... so on. So. 5A is represented in two bytes(2 sets of 4 bits): 0101 1010 = 5A = 90 = Z. The machine has to pulsate out 0 1 0 1 1 0 1 0 - which it does quite extremely fast...(It does BILLIONS of these a second!) but you have to understand that the path that the character Z takes to get from your keyboard, to the motherboard, to the processor, to memory, to your video card, then finally to your display - well is quite a task - but it does it instantly almost. But quantum scientist are hoping to do this more effectively(silly huh?) - instead of using thousands(or millions) of electrons in pulses to represent a single digit - they are hoping to use 1 electron to represent thousands(or millions) of digits!

Last edited: Sep 20, 2010
18. Sep 20, 2010

### DaveC426913

Argh! I hate that!

(But it's not endemic to IE.)

19. Sep 20, 2010

### timetravel_0

I disagree, Quantum computers will make all the differents. Fiber has the abbility to TRANSFER at 320Gbits/s with current techonology. With Quantum Computers - or even Quantum Optics(Quantum Interent!) things will be INSAINLY Fast! Think in http://en.wikipedia.org/wiki/Yottabyte" [Broken]/s!!!

Last edited by a moderator: May 4, 2017
20. Sep 20, 2010

### Staff: Mentor

You're confusing processing and data transmission. They are not the same thing.