Silicon Investor (SI) -- The First Internet Community

STOCKTALK

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor. We ask that you disable ad blocking while on Silicon Investor in the best interests of our community. If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.

Strategies & Market Trends : Gorilla and King Portfolio Candidates -- Ignore unavailable to you. Want to Upgrade?

To: Thomas Mercer-Hursh who wrote (25229)	5/23/2000 8:37:00 PM
From: LindyBill	Read Replies (1) \| Respond to of 54805

Good question, Tom. I know that the pipe is bigger with glass than wire. Perhaps the resistance in the wire is more than in the glass?

To: Thomas Mercer-Hursh who wrote (25229)	5/23/2000 8:45:00 PM
From: Seeker of Truth	Read Replies (1) \| Respond to of 54805

No, electrons don't go at the speed of light in a vacuum. If they did, according to relativity, they would acquire infinite mass. It's impossible. They don't go close to that speed but I don't remember exact velocities to quote to you. It's also true that light is slowed somewhat when it passes through any medium, be it gas liquid or solid.

To: Thomas Mercer-Hursh who wrote (25229)	5/23/2000 8:47:00 PM
From: Greg Hull	Respond to of 54805

Thomas, "Nice piece of analogy making, but I have one quibble: The reason is simple -- photons travel through glass much more quickly than electrons travel through wire. In short, optical delivery offers far more bandwidth potential than electrical delivery. I may be wrong ... it has been a while since I worked with this aspect of the stuff directly ... but isn't this technically incorrect? Is the speed of both an apprecible fraction of the speed of light, but the point being that you can send a load more information down a fiber than any corresponding piece of wire -- more the 40 lanes versus 1 lane per the analogy -- the cars aren't going any faster, there are just a whole lot more of them in any given cross section." I share your discomfort. I don't think the speed of electrons vs speed of of photons is really the issue. The ratio of the speed of light in a medium to the speed of light in a vacuum is called the index of refraction. If I remember correctly, the index is in the 1-2 range for visible light in glass and three or better for electrons in the aluminum interconnects inside an IC. The real issue is the frequency with which the data can be signaled. Maximum electrical signaling rates are in the ballpark of 10^10 Hz, while optical signaling rates are in the ball park of 10^14 Hz. This additional bandwidth is better represented as more lanes on an expressway than higher speed limits in my book. Law enforcement officers like the cliche "high rate of speed". In my book a high rate of speed is a high acceleration. Bandwidth described as "speed limit" may soon irritate me as much. Greg

To: Thomas Mercer-Hursh who wrote (25229)	5/23/2000 10:52:00 PM
From: D. Newberry	Read Replies (2) \| Respond to of 54805

The reason is simple -- photons travel through glass much more quickly than electrons travel through wire. In short, optical delivery offers far more bandwidth potential than electrical delivery. This is technically correct, but the two statements don't follow each other. Photons do travel down fiber faster than electronics propagate through copper. But that's not the point. Fiber is utilized due to its' substantial increase in bandwidth capacity. Speed is a pleasant side effect. I really liked the highway analogy. I am always looking for ways to bring technical concepts to earth, since I often give technical presentations to a non-technical audience. I particularly like the analogy of the clover leaf as a digital cross connect (the mirrors we have heard about?) However, I would like to add one caveat to the analogy. With fiber optics and cross connects alone, you can't change lanes -- each lane representing a lamda (light color) within a fiber strand. If you happen to be in the correct lane (lamda) and it feeds onto the clover leaf, then you will end up on another highway (fiber cable). If you need to change lanes, however, (go from one lamda to another) a cross connect does you no good. You must go to layer 2 or 3 functionality (switching or routing) in order to change lanes. In todays technology that means you must convert to electronics. Now, if someone can develop the equivalent of a photonic transistor, please let me know so I can invest early <g>! Regards, DN