NCEIV43 0-0813

Question 1

Lesson 43

Answer 1

Lesson 43 Are there strangers in space?

Question 2

We must conclud

Answer 2

We must conclude from the work of those who have studied the origin of life, that given a planet only approximately like our own, life is almost certain to start.

Question 3

Of all the plan

Answer 3

Of all the planets in our solar system, we are now pretty certain the Earth is the only one on which life can survive.

Question 4

Mars is too dry

Answer 4

Mars is too dry and poor in oxygen, Venus far too hot, and so is Mercury, and the outer planets have temperatures near absolute zero and hydrogen-dominated atmospheres.

Question 5

But other suns,

Answer 5

But other suns, start as the astronomers call them, are bound to have planets like our own, and as is the number of stars in the universe is so vast, this possibility becomes virtual certainty.

Question 6

There are one h

Answer 6

There are one hundred thousand million starts in our own Milky Way alone, and then there are exist is now estimated at about 300 million million.

Question 7

Although perhap

Answer 7

Although perhaps only 1 per cent of the life that has started somewhere will develop into highly complex and intelligent patterns, so vast is the number of planets, that intelligent life is bound to be a natural part of the universe.

Question 8

If then we are

Answer 8

If then we are so certain that other intelligent life exists in the universe, why have we had no visitors from outer space yet?

Question 9

First of all, t

Answer 9

First of all, they may have come to this planet of ours thousands or millions of years ago, and found our then prevailing primitive state completely uninteresting to their own advanced knowledge.

Question 10

Professor Ronal

Answer 10

Professor Ronald Bracewell, a leading American radio astronomer, argued in Nature that such a superior civilization, on a visit to our own solar system, may have left an automatic messenger behind to await the possible awakening of an advanced civilization.

Question 11

Such a messenge

Answer 11

Such a messenger, receiving our radio and television signals, might well re-transmit them back to its home-planet, although what impression any other civilization would thus get from us is best left unsaid.

Question 12

But here we com

Answer 12

But here we come up against the most difficult of all obstacles to contact with people on other planets – the astronomical distances which separate us.

Question 13

As a reasonable

Answer 13

As a reasonable guess, they might, on an average, be 100 light years away.

Question 14

(A light year i

Answer 14

(A light year is the distance which light travels at 186,000 miles per second in one year, namely 6 million million miles.) Radio waves also travel at the speed of light, and assuming such an automatic messenger picked up our first broadcasts of the 1920’s, the message to its home planet is barely halfway there.

Question 15

Similarly, our

Answer 15

Similarly, our own present primitive chemical rockets, though good enough to orbit men, have no chance of transporting us to the nearest other star, four light years away, let alone distances of tens or hundreds of light years.

Question 16

Fortunately, th

Answer 16

Fortunately, there is a ‘uniquely rational way’ for us to communicate with other intelligent beings, as Walter Sullivan has put it in his excellent book, We Are not Alone.

Question 17

This depends on

Answer 17

This depends on the precise radio frequency of the 21-cm wavelength, or 1420 megacycles per second.

Question 18

It is the natur

Answer 18

It is the natural frequency of emission of the hydrogen atoms in space and was discovered by us in 1951; it must be known to any kind of radio astronomer in the universe.

Question 19

Once the existe

Answer 19

Once the existence of this wave-length had been discovered, it was not long before its use as the uniquely recognizable broadcasting frequency for interstellar communication was suggested.

Question 20

Without somethi

Answer 20

Without something of this kind, searching for intelligences on other planets would be like trying to meet a friend in London without a pre-arranged rendezvous and absurdly wandering the streets in the hope of a chance encounter.