Quote from a BBC interview with Douglas Adams : "Technology is a word which means something that doesn’t work yet".
* "Conjecture" - guess, assume, hypothesize, imagine, surmise, dare say.
"Conjectures are of great importance since they suggest useful lines of research" Alan Turing COMPUTING MACHINERY AND INTELLIGENCE (1950) - "I propose to consider the question, "Can machines think?"
Suggest a link for this section
The following diagram shows the effects at the Earth's
On one side the high centripetal acceleration is partially cancelled by
Moon's gravity. On the other side the smaller centripetal acceleration
combines with the Moon's gravity. The Earth's oceans therefore
experience a similar magnitude of
acceleration on either side - producing two high tides per day!
Note: this explanation is in some high school science texts but is rarely covered in popular encylopedias. The values in the illustration are guesses but are in roughly the correct proportions.
One matter which should not be overlooked is the possibility that early life was transported from Earth to Mars in a similar manner to the way the Martian "fossil" got to Earth. It could even be that life started on Mars (or elsewhere) and seeded the Earth in the same way. The July 1994 issue of Planetary Report has an article Swapping Rocks: Exchange of Surface Material Among the Planets by H Jay Melosh. The article explains how this might occur and covers ejection, transit and "re-entry". It is estimated that about half a tonne of Martian material falls to Earth each year.
Consider the odds in the case of the Martian "fossil" meteorite: A rock containing micro-fossils was blasted off the surface of Mars by another meteorite some 15 million years ago. This orbited the Sun until it fell to Earth on Antarctica some 10,000 years ago. On the Earth today, what are the chances of a rock containing a fossil being picked up compared with one containing live organisms? I would suggest at least 1000 times less! On Earth today (or Mars 15 million years ago), what are the chances of a chunk of rock being blasted into space by a meteorite impact, compared with the conditions 4 billions years ago? Meteorite impacts were much more frequent at that time (when life is thought to have arisen). This suggests that the chances are also at least 1000 times less. The odds of a Martian fossil being blasted into space 15 million years ago are therefore likely to be at least 1 million (1000 x 1000) times less than the chances of a rock containing live organisms being blasted into space 4 billion years ago!
Assuming that some of the organisms could survive the journey through space then the possible discovery of a Martian fossil on Earth at least suggests the possibility of Mars or the Earth being seeded from space.
Update Jan 97: Exchange of early life between Earth and Mars (in both directions) could help explain the recent finding of possible signs of life on Earth some 3.9 billion years ago, before the massive asteroid bombardment which heavily cratered the Moon. The sequence might be: life gains a foothold on Earth (either evolves or is seeded from elsewhere); Earth rocks with live organisms reach Mars and life is established on Mars; Earth is bombarded by asteroids, destroying any life here; Mars rocks reach Earth, re-establishing life here. Carl Sagan pointed out this possibility in 1988!
Update May 98: Chris Chyba's paper "The Origin of Life in a Cosmic Context" in the newly published book "Carl Sagan's Universe" discusses the possibility of "panspermia" between Mars, Earth and Venus.
See also New Scientist Survivors
Mars by Paul Davies and his new book 'The
Fifth Miracle' which explores these ideas, and many more about the
of life. Carl Sagan's popular science book Planets
, written in 1966, refers to the possibility rocks from Earth seeding
the Moon with microbiotic life.
This discussion is continued on the Transpermia
First posted December 1996. Updated 13 Dec 1997 based on advice from Chris White.
The Moon is a body of extreme cold and extreme heat. On most locations on the moon daylight "day" lasts 14 Earth days then there are 14 Earth days of darkness - pretty harsh conditions. However, the tilt of the Moon's rotational axis is only about 1.5 degrees to the Earth/Moon's orbital plane around the sun. There is a giant basin (dip) at the lunar South Pole which has large areas in permanent darkness. Furthermore, some points on the rim are in permanent sunlight. Therefore a base located at the South Pole would have permanent access to very cold and very hot locations - ideal for generating electricity (the principle of an electric power station is that there is a source of "heat" which is at a higher temperature than the surroundings). Unlike on Earth, there is no atmosphere to diminish the intensity of sunlight at the poles but the collectors would need to face nearly horizontal.
There is talk of mining Helium on the moon to generate power by nuclear fusion. Even if the huge difficulties of building a fusion reactor on the moon could be overcome (assuming that a fusion reactor is, in fact, possible), it seems to me that the best source of fusion power (the Sun) is being overlooked.
Sample screen dump.
The speed of sound is roughly 300 metres per second (actually
344m/s). If the runner in the outside lane is 6 metres further away
from the starter's pistol than the runner in the inside lane then the
sound of the pistol will
reach that runner 6/300 = 0.02 of a second later. Therefore the inside
runner has two-one-hundredths of a second advantage. Given that
world-level races are won and lost in less than one-hundredth of a
second it is important that this effect is taken into account (is
Top of page
Pet parasites might alter the human brain
This low-key article from New Scientist might be the key to explaining people's response to pets:
Parasite hijacks brains with surgical precision
A mere parasite controls the fate of rats and mice by hijacking the part of the brain that makes the rodents naturally fear cats, a new study shows. Rats and mice normally flee if they smell cat urine, but not if they're infected by the protozoan parasite Toxoplasma gondii. The parasite can only complete its life cycle if its rodent host is eaten by a cat, so it "brainwashes" the creature into apparently liking the scent.
and Cosmos magazine: Parasite gives rats suicidal cat attraction
...It is spread when the parasite is passed out in cat faeces and contaminates soil, where rats and mice pick up the infection. The parasite's lifecycle is completed when the mind-altered rats, which have been shown to be less fearful of cats and have slower reaction times, are caught and eaten...Around 15 to 20 per cent of Americans are infected with the parasite...
New Scientist Dec 2012: Parasite makes mice fearless by hijacking immune cells - more on Toxoplasma
So there is a possibility that similar parasites, passed on by pet cat or dog saliva or faeces, might alter the brains of their human owners. This might explain why some dog owners do not experience revulsion at dog "functions" that are not accepted behaviour by humans - urinating and defaecating in public and licking the face of people (particularly children). You would expect that these actions would have been bred out of dogs after thousands of years of domestication and selective breeding.
Science Jan 2014 ($): Parasitic Puppeteers Begin to Yield Their Secrets.
Jun 2015 New Scientist: The cat made me do it: Is your pet messing with your mind?
6 Apr 16 New Scientist: Explosive road rage-like anger linked to parasite spread by cats
How much kinetic energy is in falling rain?
Say we have 10mm of rain falling in one hour. That means 0.01 x 1 x 1 = 0.01 cubic metres = 10 kg per hour.
Wikipedia states that a 5mm diameter rain drop hits the ground with a speed of 9 m/s. The kinetic energy of 10mm of rain falling on one square metre of ground for one hour is therefore ( half x mass x velocity squared):
0.5 x 10 x 9 x 9 = 405 Joules (per sq m per hour) = 0.11 Watt-hours (per sq m per hour)
Therefore a heavy rain shower will deliver (power of) about 0.11 Watts per square metre (compared with a solar panel that generates about 200 Watts per square metre under good conditions). Of course there would be major loses converting the rain's kinetic energy into usable energy.
Oh well ...