ROBERT GODDARD (1882-1945)

1915 – USA

‘Demonstrates that rocket engines can produce thrust in a vacuum’

Photograph of DR ROBERT H GODDARD ©

DR ROBERT H GODDARD

‘Robert Goddard stands as the epitome of the early American desire to conquer space’

It was generally believed that it would be impossible for a rocket to move outside of the earth’s atmosphere, as there was nothing for it to push against in order to gain propulsion. Goddard had already gone a long way to revoking this assumption by 1907 in completing calculations to show that a rocket could thrust in a vacuum, and had backed up this concept with physical experiment in 1915.

His booklet “A Method of Reaching Extreme Altitudes” described the multi-stage principle and presented advanced ideas on how to improve the performance of solid-fuel rockets.

‘I have read very attentively your remarkable book A Method for Reaching Extreme Altitudes edited in 1919 and I have found in it quite all the ideas which the German Professor H.Oberth published in 1924′ (in a letter from Soviet engineer & author Nikolai Alexsevitch Rynin)

In 1926 he launched the world’s first liquid fuelled rocket using gasoline and liquid oxygen. Over the next decade, Goddard filed patents for guidance, control and fuel pump mechanisms.

In spite of his success (by 1935 he had launched a rocket at Roswell, New Mexico which traveled faster than the speed of sound and another which achieved an altitude of 1.7 miles, then a record) the US Government largely ignored his efforts until the space race gathered momentum in the 1940s and 1950s. The government was eventually forced to pay one million dollars to Goddard’s widow for patent infringement in acknowledgement of the use they had made of his designs as a basis from which to begin development.

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ISAAC ASIMOV (1920- 92)

1940 – USA

  • First Law: A robot may not injure a human being or, through inaction, allow a human being to come to harm

  • Second Law: A robot must obey orders given it by a human being, except where such orders would conflict with the First Law

  • Third Law: A robot must protect its own existence as long as such protection does not conflict with the First or Second Law

The word robot was introduced into the English language from a 1921 play RUR (Rossum’s Universal Robots) by Czech playwright Karel Capek.

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GORDON MOORE (b.1929)

1965 – USA

‘The number of transistors on a computer doubles every 18 months or so’

library photo of GORDON MOORE

GORDON MOORE

In 1965, one of the founders of chipmaker Intel observed the exponential growth in the number of transistors per silicon chip and made his prediction which is now generally referred to as Moore’s law.

3D reconstruction chip surface (500x)

In 1971 the first Intel chip, 4004, had 2300 transistors. In 1982 the number of transistors increased to 120,000 in the 286, in 1993 to 3.1 million in the Pentium and in 2000 to 42 million in the Pentium 4.
Heat production is now the limiting factor in the production of silicon chips with millions of transistors.

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EDWIN HUBBLE (1889-1953)

1929 – USA

‘Galaxies are moving away from each other and us at an ever-increasing rate. The more distant the galaxy, the faster it is moving away’

Photo portrait of EDWIN HUBBLE with pipe ©

EDWIN HUBBLE

This means that the universe is expanding like a balloon. The principle of an expanding cosmos is at the heart of astronomical theory.

Before 1930, astronomers believed that the Milky Way was the only galaxy in the universe. The discovery of Cepheid variables, which brightened and dimmed in a regular rhythm gave a clue as to the true size of the universe.

In 1923, Hubble spotted a Cepheid variable in the Andromeda Nebula, previously supposed to be clouds of gas. This led to the conclusion that Andromeda was nearly a million light years away, far beyond the limits of the Milky Way and clearly a galaxy in its own right. Hubble went on to discover Cepheids in other nebula and proved that galaxies existed beyond our own.
He began to develop a classification system, sorting galaxies by size, content, distance, shape and brightness. He divided galaxies into elliptical, spiral, barred spiral and irregular. These are subdivided into categories, a, b and c according to the size of the central mass of stars within the galaxy and the tightness of any spiraling arms.

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The Earth’s atmosphere alters light rays from outer space; the Hubble Space Telescope, being above the atmosphere, receives images with far greater clarity and detail than any Earth-based optical instrument and its camera can achieve a resolution ten times greater than the largest Earth based telescope.
Construction began on the HST in 1977 and it was launched by the space shuttle Discovery on 25 April 1990. The instruments can detect not only visible light but also infra-red and ultra-violet.

Hubble noticed that the galaxies appeared to be moving away from the region of space in which the Earth is located. It appeared that the further away a galaxy was, the faster it was receding. The conclusion was that the universe, which had previously been considered static is in fact expanding.

In 1915, EINSTEIN’s theory of relativity had suggested that owing to the effects of gravity, the universe was either expanding or contracting. Einstein knew little about astronomy and had introduced an anti-gravity force into his equations, the cosmological constant. Hubble’s discoveries proved Einstein had been right after all and Einstein later described the introduction of the gravitational constant as ‘the biggest blunder of my life’.

Hubble’s discovery that the universe is expanding led to the development of the ‘big-bang’ model of the universe.

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WILLARD LIBBY (1908- 80)

1946 – USA

‘Radiocarbon can be used to estimate the age of any organic material. The radioactive isotope of carbon,14C (carbon-14) is present in all living things. When life stops 14C begins to decay. From the rate of decay the age (or time of death) of an organism can be calculated’

The two most common forms of carbon 12C and 13C, make up virtually all types of carbon and are stable – 12C is the simplest form and is made up of 6 protons and 6 neutrons; 13C is slightly heavier because it has one more neutron. 14C, known as radiocarbon has the unstable combination of 6 protons (defining it as carbon) and 8 neutrons.

In the late 1940s Libby led the team at the University of Chicago, USA, that developed radiocarbon dating using the radioactive isotope 14C.

Living things go on absorbing 14C until the time of their death. The half-life of 14C is 5730 years – once an organism dies, 14C begins to decay. As a result the ratio of 12C to 14C changes with time. By measuring this ratio, it can be determined when the organism died.

Libby suggested that minute amounts of radiocarbon come from the upper part of the atmosphere. He put forward the idea that when high-energy particles formed in deep space – cosmic rays – reach the atmosphere, they interact with nitrogen gas to form radiocarbon. He argued that the newly formed radiocarbon is rapidly converted to carbon-dioxide, CO2, and is taken up by plants during photosynthesis; with the result that the radiocarbon enters the food chain. Everything alive should therefore have the same radiocarbon concentration as the atmosphere.

Once an individual dies, some of the 14C atoms begin to disintegrate and give off an electron to reform nitrogen. Libby argued that if the original radiocarbon content is known. it should be possible to measure the remaining 14C in a sample of tissue to back-calculate its age, in a similar way to estimating how much time has passed by measuring the amount of sand left in the top of an egg timer.
By the end of the 1940s, Libby and his team had shown that the radiocarbon content of the air was the same around the world and that 14C could be used to date anything organic.

The crucial principle is the half-life of the unstable atom, the rate at which it will break down. The longer the half-life of a material, the further back in time a dating method can go. With radiocarbon, the dating range is 40,000 to 60,000 years.

When Libby originally measured the half-life of radiocarbon, he calculated it to be just over 5720 years. During the 1950s a new estimate of 5568 years was made by other researchers, who assumed that Libby had got his figures wrong and the 5568-year half-life was adopted by the scientific community.
It is now known that the half-life of radiocarbon is 5730 years, virtually identical to Libby’s original estimate. As a result of the large number of samples that had already been dated, the incorrect value of 5568-years is used in estimates – confusingly this is now termed the ‘Libby half-life’. As all labs use the same half-life value, all ages are directly comparable.

With radiocarbon dating the assumptions made are:

  1. that the atmosphere has had the same 14C content in the past as today
  2. that all things alive have the same radiocarbon content as one-another and as the atmosphere
  3. that no more radiocarbon is added to a sample after death

To obtain a final radiocarbon age, we have to use a point in time to compare against. 1950 is used as year zero and all ages are described relative to this as ‘before present’ (BP). Radiocarbon dating does not give a precise date and estimates are given within a range of uncertainty.

Libby received numerous awards for this work,including the 1960 Nobel Prize for Chemistry. Libby also worked on the Manhattan Project during World War II, helping to enrich the uranium used in the atomic bombs.

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FRED LAWRENCE WHIPPLE (1906-2004)

1951 – USA

Photograph of Whipple ©

FRED WHIPPLE

‘A typical comet has three parts: a frozen central part called the nucleus, a fuzzy cloud surrounding the nucleus called the coma (or head) and a tail consisting of gas and dust. The nucleus, usually only a few kilometres across is made of grains of frozen water, methane, ethane, carbon dioxide, ammonia and other gases’

photo pf comet hale-bopp

COMET HALE-BOPP

Whipple coined the phrase ‘dirty snowball’. In 1986 the European Space Agency‘s craft Giotto proved that Whipple’s theory is fairly accurate when it took close-up photographs (from a distance of 480 kilometres) of the nucleus of HALLEY‘s comet.

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BENJAMIN THOMPSON (1753-1814): known as Count Rumford

1798 – England

‘Mechanical work can be converted into heat. Heat is the energy of motion of particles’

Heat is a form of energy associated with the random motion of atoms or molecules. Temperature is a measure of the hotness of an object.

Portrait of COUNT RUMFORD ©

COUNT RUMFORD

In the eighteenth century, scientists imagined heat as a flow of a fluid substance called ‘CALORIC‘. Each object contained a certain amount of caloric. If caloric flowed out, the object’s temperature decreased; if more caloric flowed into the object, its temperature increased.
Like phlogiston, caloric was a weightless fluid, a quality that could be transmitted from one substance to another, so that the first warmed the second up. What is being transmitted is heat energy.

One idea was that a hot object would emit ‘calorific rays’, whilst a cold one would emit ‘frigorific rays’ – an idea raised in Plutarch’s De Primo Frigido. Cold was an entity in itself, not simply the absence of heat.

It was believed that all substances contained caloric and that when a kettle was being heated over a fire, the fuel gave up its caloric to the flame, which passed it on to the metal, which passed it on to the water. Similarly, two pieces of wood rubbed together would give heat because abrasion was releasing caloric trapped within.

Working for the Elector of Bavaria, Rumford investigated the heat generated during the reaming out of the metal core when the bore of a cannon is formed. According to the caloric theory, the heat was released from the shards of metal during boring; Rumford noticed that if the tools were blunt and removed little or no metal, more heat was generated, rather than less. Rumford postulated that the heat source had to be the work done in drilling the hole. Heat was not an indestructible caloric fluid, as LAVOISIER had argued, but something that could come and go. Mechanical energy could produce heat and heat could lead to mechanical energy.

One analogy he drew was to a bell; heat was like sound, with cold being similar to low notes and hot, to high ones. Temperature was therefore just the frequency of the bell.

Rumford thought there was no separate caloric fluid and that the heat content of an object was associated with motion or internal vibrations – motion which in the case of the cannon was bolstered by the friction of the tools.
He had recognized the relationship between heat energy and the physicists’ concept of ‘work’ – the transfer of energy from a system into the surroundings, caused by the work done, results in a difference in temperature.
This transfer of energy measured as a temperature difference is called ‘heat’.

Half a century was to pass before in 1849, JAMES JOULE established the ‘mechanical equivalence of heat’ and JAMES CLERK MAXWELL launched the kinetic theory. According to Maxwell, the heat content of a body is equivalent to the sum of the individual energies of motion (kinetic energies) of its constituent atoms and molecules

US born Rumford founded the Royal Institution in London and invented the calorimeter, a device measuring heat.

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