Space Elevator Climbs at MIT

"Yes, and my car has a 200hp engine no bigger than a toaster. When it gets down to the size of AAA cell, I'll start to think the space elevator could happen.

Because, in case you don't get it, these are the kinds of physical parameters we're talking about here. Subtlety won't cut it."

Yeah well every time I hear an expert tell me it can't be done I think of the Noise Barrier and remember that the problem was solved with something no one in the industry had even considered.

All types of bureaucratic systems are subject to the effects of dogma, even the scientific community.

I found an article that addresses this lateral acceleration problem, here's an excerpt:

If you go through the math quantitatively, the angular momentum for the climbers requires a few newtons of force over the one-week travel time, and we do that easily with our many tons of material in the anchor and the counterweight. The additional angular momentum will eventually be recovered from that of the entire Earth. The quantities really are tiny, but just to be complete, a climber going up pushes the entire elevator slightly to the east, causing it to lean. However, the ribbon recovers for the same reason that it stays up in the first place. Centripetal acceleration is acting on the counterweight pulling it outward, and the lost angular momentum is replaced very quickly (essentially as fast as it is lost). The ribbon will never lose enough angular momentum to even deflect a single degree, let alone fall. The extra angular momentum is stolen from the Earth's rotation; we will have to worry about this effect slowing down the Earth and making the day longer if we ever decide to ship Australia into space.

Frequent Misconceptions

"The problem with tape hiss was never solved by digital encoding, but avoided in the same way that music playing off a CD avoids needle clicks/pops heard on LPs."

No, the problem was you could not make a recording of a recording because you would lose quality due to noise. In other words the goal was not to get rid of tape hiss the goal was to make a recording of a recording and not lose quality in the process.

The Recording Industry invested lots of money into all sorts of ideas (Dolby Noise Reduction, Multi-Tracking, etc.)

What made the process viable was a paradigm shift, or a new way to use tape and/or magnetic media by digitally encoding and decoding the signal.

"Yes but "perfect copy" doesn't mean immortal. It will continue to degrade unless serious back-up and redundancy measures are taken (presumably that could be done until the sun explodes.... but practically speaking, remember that CDs were supposed to last "a lifetime" and now we find out that means only 20 or 30 years)."

All very valid points but before that CD degrades I can make a copy of it and the new copy is virtually identical. This was not possible before digital technology.

Entropy is not denied in the digital process, just pushed back a bit.

What made the process viable was a paradigm shift, or a new way to use tape and/or magnetic media by digitally encoding and decoding the signal.

What do you think I said in the rest of my post? My simple example regarding the CD versus the LP needle pop was to show that the problem isn't there because CD audio content is not picked up with a needle, just as analog tape noise/hiss is not decoded along with a digital bitstream.

The problem with analog tape used for audio production is that the noise is not able to be separated from the audio content because it is produced/reproduced the same way the audio is; digital encoding separates the two even on the same medium. "Noise reduction" units function on the principle of "pre-emphasis", which boosts the audio within the range of the hiss by a large number of dB before it is put to tape. Then, upon playback, the pre-emphasis is removed as the audio in that range is attenuated by the same number of dB, essentially pushing the noise floor down by the same amount.

This is fine on it's own, but the problem is that magnetic tape, no matter how high the quality, has a finite dynamic range. The pre-emphasis can only be pushed up so high before the limits of the tape begin to compression-distort the audio (before saturation, the equivalent of all "1"s in digital), which is detrimental to audio fidelity. Very dynamic audio suffers the same fate, even without regard to pre-emphasis. It's fine if one is looking for that sound on something with a high transient response like a snare, but ultimately it could only go so far due to the limits of analog tape.

That said, there are still many people in the recording industry who say analog tape sounds better, but with the new stuff coming out, it's increasingly difficult to make that argument. The probleim of phase-shifting when using EQ is also becoming a non-issue with digital technology.

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