04 NOV 2018 by ideonexus

 A Computer Algorithm for Randomization

Back in the early days of computers, one of the more popular methods of generating a sequence of random numbers was to employ the following scheme: 1. Choose a starting number between 0 and 1. 2. Multiply the starting number by 4 ("stretch" it). Subtract 4 times the square of the starting number from the quantity obtained in step 2 ("fold" the interval back on itself in order to keep the final result in the same range). 3.Given a starting number between 0 and 1, we can use the proce-dure...
Folksonomies: algorithms randomization
Folksonomies: algorithms randomization
  1  notes

From John Casti.

22 JUN 2013 by ideonexus

 A Brief History of Signals

Prior to the advent of practical electrical communication, human beings had been signaling over a distance in all kinds of ways. The bell in the church tower called people to religious services or “for whom the bell tolls”—the announcement of a death. We knew a priori several things about church bells. We knew approximately when services were to begin, and we knew that a long, slow tolling of the bells announced death. Thus we could distinguish one from the other, namely a call to relig...
Folksonomies: communications signals
Folksonomies: communications signals
  1  notes

From church bells, speech, body language, semaphores, fires, and smoke signals.

01 JAN 2012 by ideonexus

 The Pioneer 10 Plaque

On the title page of this chapter is shown the message. It is etched on a 6-inch by 9-inch gold-anodized aluminum plate, attached to the antenna support struts of Pioneer 10. The expected erosion rate in interstellar space is sufficiently small that this message should remain intact for hundreds of millions of years, and probably for a much longer period of time. It is, thus, the artifact of mankind with the longest expected lifetime. The message itself intends to communicate the locale, ep...
  1  notes

Carl Sagan describes everything that went into the symbolism of this message sent to the stars.