Human History

Human History

Human history can be viewed as a slowly dawning awareness that we are members of a larger group. Initially our loyalties were to ourselves and our immediate family, next, to bands of wandering hunter-gatherers, then to tribes, small settlements, city-states, nations. We have broadened the circle of those we love. We have now organized what are modestly described as superpowers, which include groups of people from divergent ethnic and cultural background working in some sense together – surely a humanizing and character-building experience.

If we are to survive, our loyalties must be broadened further, to include the whole human community, the entire planet Earth. Many of those who run the nations will find this idea unpleasant. They will fear the loss of power. We will hear much about treason and disloyalty. Rich nations will have to share their wealth with poor ones. But the choice, as H. G. Wells once said in a different context, is clearly the universe or nothing.

A reasonable – even an ambitious – program of unmanned exploration of the planets is inexpensive. The budget for space sciences is not very expensive. Comparable expenditures in many countries are more or less the same. Together these sums represent the equivalent of two or three nuclear submarines per decade, or the cost overruns on one of the many weapon systems in a single year. In the last quarter of 1979, the program cost of the U.S. F/A-18 aircraft increased by $5,1 billion, and the F-16 by $3,4 billion. Since their inceptions, significantly less has been spent on the unmanned planetary programs of both the United States and the Soviet Union than has been wasted shamefully – for example, between 1970 and 1975, in the U.S. bombing of Cambodia, an application of national policy that cost $7 billion. The total cost of a mission such as Viking to Mars, or Voyager to the outer solar system, is less than that of the 1979-80 Soviet invasion of Afghanistan. Through technical employment and the stimulation of high technology, money spent on space exploration has an economic multiplier effect. One study suggests that for every dollar spent on the planets, seven dollars are returned to the national economy. And yet there are many important and entirely feasible missions that have not been attempted because of lack of funds – including roving vehicles to wander across the surface of Mars, a comet rendezvous, Titan entry probes and a full-scale research for radio signals from other civilizations in space.

Carl Sagan, Cosmos.

Even an ambitious program of unmanned space exploration in inexpensive. Image: Space Travel by © Megan Jorgensen.

X Ray Tech Salary

X Ray Tech Salary

Any society with a marked population explosion will be forced to devote all its energies and technological skills to feeding and caring for the population on its home planet. Technicians will be busy and tech salaries will go up. On any planet, no matter what its biology or social system, an exponential increase in population will swallow every resource.

We can predict thus that no civilization can possibly survive to an interstellar spacefaring phase unless it limits its numbers.

Of course, this is a very powerful conclusion and is in no way based on the idiosyncrasies of a particular civilization.

Conversely any civilization that engages in serious interstellar exploration and colonization must have exercised zero population growth or something very close to it for many generations.

The famous astronomer Carl Sagan and his colleague William Newman have calculated that if a million years ago a spacefaring civilization with a low population growth rate emerged two hundred light-years away and spread outward, colonizing suitable worlds along the way, their survey starships would be entering our solar system only about now.

But a million years is a very long period of time. If the nearest civilization is younger than this, they would not have reached us yet. A sphere two hundred light-years in radius contains 200,000 suns and perhaps a comparable number of worlds suitable for colonization. It is only after 200,000 other worlds have been colonized that, in the usual course of things, our solar system would be accidentally discovered to harbor indigenous civilization.

What does it mean for a civilization to be a million years old? We have had X rays, radio telescopes and spaceships for a few decades; our technical civilization is young, scientific ideas of a modern cast a few thousand, civilization in general a few tens of thousands of years; human beings evolved on this planet only a few million years ago. At anything like our present rate of technical progress, an advanced civilization millions of years old is as much beyond us as we are beyond a bush baby a macaque.

Will a civilization with a low population growth reach some lush Eden? Illustration by Elena.

Used Transmissions for Sale

Used Transmissions for Sale

The two Voyager spacecraft are bound for the Galaxy. Affixed to each is a gold-plated copper phonograph record with a cartridge and stylus and, on the aluminum record jacket, instructions for use. The humans sent data about their genes, something about their brains, and something about their libraries to other beings who might sail the sea of interstellar space. Although the recipients do not know any languages of the Earth, included are greetings in sixty human tongues, as well as the hellos of the humpback whales.

Photographs of humans from all over the world are attached, caring for one another, learning, fabricating tools and art and responding to challenges.

There is an hour and a half of exquisite music from many cultures, some of it expressing the sense of cosmic loneliness, the wish to end this isolation, the longing to make contact with other beings in the Cosmos. Recordings were sent of the sounds that would have been heard on this planet from the earliest days before the origin of life to the evolution of the human species and our most recent burgeoning technology. It is a love song cast upon the vastness of the deep.

But the Earth did not want to send primarily scientific information. Any civilization able to intercept Voyager in the depths of interstellar space, its transmitters long dead, would know far more science than the terrestrial science does.

Instead the Voyagers tell those other beings something about what seems unique about the Earthlings.

The interests of the cerebral cortex and limbic system are well represented; the R-complex less so.

In this spirit the people who launched the Voyagers included on the spacecraft the thoughts and feelings of one person, the electrical activity of the brain, heart, eyes and muscles, which were recorded for an hour, transcribed into sound, compressed in time and incorporated into the record.

In one sense the Humans have launched into the Cosmos a direct transcription of the thoughts and feelings of a single human being in the month of June in the year 1977 on the planet Earth.

Perhaps the recipients will make nothing of it, or think it is a recording of a pulsar, which in some superficial sense it resembles.

Many, perhaps most, of recorded messages will be indecipherable. But the Earth sent them because it is important to try.

Or perhaps a civilization unimaginably more advanced than the Humanity will be able to decipher such recorded thoughts and feelings and appreciate these efforts to share all these thought with them.

We have sent our messages because it is important to try, not because we’d like to sell used transmission. Image: © Megan Jorgensen.

How Do Lasers Work?

How do lasers work?

If you knew what the letter stood for you might be able to guess from the name itself that a laser, which stands for Light Amplification by the Stimulated Emission of Radiation, is a device used to create a very special kind of light beam.

Ordinary light – the kind we flip on with a wall switch – in incoherent. All we mean by this is that the light waves are emitted in a random, disorganized way, going in different directions and out of phase – that is not in step with one another. For example, when we turn of a fluorescent lamp, a current of electrons is sent through the fluorescent tube, bombarding the atoms inside. This excites the atoms to a state of energy higher than normal. When they return to their normal energy state, that is when they give off their light. But since each atom is bombarded, excited and gives off its light energy at random directions and times, the light waves which come from the fluorescent tube are still mixed together, like a troop of drummers who refuse to keep time with one another.

In a laser, though, the atoms all keep time together, and the light waves they give off are pointed in the same direction, with their crests and troughs aligned with one another. This is why we say laser light is coherent. Coherence is what makes laser beams so special.

To create a laser beam, we first of all need to have material whose atoms can be excited and remain excited long enough so that a collection of them can be made to radiate together. One of the early kinds of lasers used a synthetic ruby crystal to accomplish this.

The crystal was machined into the shape of a small cylinder. Its ends were made parallel, polished flat and smooth, and coated with silver to make them act as mirrors. Using this apparatus, here is what happens: when the first of the group of simulated falls to its normal state, and, in so doing, radiates light, that light comes in contact with another of the excited atoms, and it too radiates light. And, what is more, the light waves from both atoms will be in step – that is, in phase. When the light waves from these two atoms hit other excited atoms, they too will be stimulated to emit light in step.

Any light waves which are emitted in the wrong direction – that is, in any direction but parallel to the walls of the cylinder – will bounce through the walls and escape. But the light waves which do travel parallel to the walls will continue to be reflected back and forth by the mirrors at each end, at the same time stimulating other excited atoms to do the same. In this way the light increases in intensity, just as the drummers would sound louder and louder if, one by one, they started keeping time together.

Is one of the mirrors is built so that it will allow a small amount of light to escape, the beam which results will come out straight ahead, the crests and trough of each light wave aligned in unison. It will be coherent. And it will have very little “spread” – unlike a flashlight beam, for example, which in just a few feet spreads out from its initial small diameter to a large circle.

Many other kinds of materials – solid, liquid and gaseous – have been used to create lasers. Some emit different colors – that is, different wavelengths – other than the red of the ruby laser. Other requires less power to operate.  At TRW, for example, where were laser research began in 1961, they developed a portable laser the size of a flashlight. An argon ion gas laser uses a TRW-developed high-current cold cathode (electron emitter) which greatly reduces the power requirements (because of their large power requirements most lasers must remain stationary).

Lasers have many practical as well as scientific uses. A ruby laser, for example, which puts forth its radiation in a thousandth of a second, is used to surgically weld a torn of detached retina of the eye.

Because it is highly directional, that is, it has very little spread - a laser beam will carry over great distances. A dramatic example of this is seen when a laser is used to illuminate a mile-wide spot on the Moon.

One laser beam has an extremely high frequency – a thousand million cycles per second. This gives it more information-carrying capacity than any radio, tv, or any other communication channel now in existence.

Another application of laser technology is holography, a remarkable kind of three-dimensional photography. What makes a hologram so unusual is that it really is three-dimensional. You can move to the side of a hologram and actually see behind the objects in the foreground, as though you were looking through a window.

These pictures are photographs of holograms developed during research at TRW, they are different aspects of the same scene. They were made by viewing a single hologram from three different angles. The three-dimensional aspects of holography make it extremely useful for studying particles of droplets in a dispersion pattern. For this reason holography is a valuable tool for evaluating many kinds of nozzles and vaporizing devices, including paint spray guns, oil burners, fuel injectors and carburetors. The photographs show the dispersion of droplets in two impinging water jets.

At TRW, holography research began in 1963, when they studied the behaviour of electrostatically charged droplet streams in air and vacuum for the Air Force. Later, they work in the field expanded to holography of moving subjects at high-speed events, holographic microscopy and spectroscopy, optical gauging by holography, and acoustic holography.

Engineers of the NASA Goddard Space flight Center send a message by laser beam to a satellite in orbit.

Basic Neurochemistry and Psychopharmacology

Basic Neurochemistry and Psychopharmacology

Channel functions operate primarily with the classical neurotransmitters glutamate, aspartate and GABA. The state functions too operate with these same neurotransmitters, but also with a number of others, such as serotonin and dopamine. The latter terms may be familiar to you because psychopharmacologists work constantly with these neurotransmitters – and herein lies an interesting connection. It is no accident that the most familiar aspects of psychopharmacology deal with these chemicals, which convey the influence on the brain of the internal milieu – the “drives”. What then, are the chemicals that govern the internally directed systems?

The first is the neurotransmitter acetyicholine (Ach), which is employed by a good many neurons throughout the brain. Neurons using this neurotransmitter are called cholnergic neurons, and two such systems are of specific interest. The first cholinergic system arises in the mesopontine tegmentum (part of the reticular formation, in the back half of the pons). These neurons project via the thalamus and influence the cortex in a fairly global way.

Only the cell bodies of these acetyl-choline-producing neurons are found in the brainstem structures of the pontine tegmentum. The axons of these cells extend into sites in the hypothalamus, thalamus, and cerebral cortex, to other cells and modify the firing rates of those cells with Ach having narrow sites of origin (cell bodies clumped together in nuclei) and broad regions to which they project (via their axons) – applies to all the systems. A second (and very important) state-dependent system that employs Ach has its origin in the basal forebrain nuclei. This system, too, globally affects the firing rate of almost the entire cortex.

The next important state-dependent neurotransmitter system has its origins in the raphe nuclei of the brainstem. These neurons produce serotonin (5HT) and deliver it widely in the forebrain. Serotonin is well known for its use in antidepressant medications – the SSRIs (selective serotonin reuptake inhibitors). This phrase allows us to expand slightly our knowledge of cellular neurophysiology. A neurotransmitter is excreted via an axon into the synaptic space, where it attaches to receptors on the next neuron and thereby increases or reduces its firing rate.

Neurotransmitters define our lives. Photo by Elena.

An additional fact is that the neurotransmitter is not lost in the second cell. After a period of time, the neurotransmitter is absorbed back into the first cell, so that it can be reused. This process of retrieving the neurotransmitter back into the first cell, so that it can be reused. This process of retrieving the neurotransmitter is called “reuptake”. SSRIs are reuptake inhibitors, which implies that they slow the process of reabsorbtion or the neurotransmitter back into the first cell. This means that the excreted neurotransmitter is active in the synaptic space for a longer period of time and excites the second neuron accordingly. Any chemical that inhibits reuptake of a neurotransmitter has the effect of rendering the neurotransmitter (in this case, serotonin) more effective by making is longer-lasting.

The third class of neurotransmitter that has its origin in a core brainstem nucleus is called norepinephrine (NE: known as noradrenaline in Britain). This neurotransmitter has its source celles in the nucleus locus coeruleus of the pons. As with other state-dependent systems, the sites of action of this system are extremely diverse.

The last of the neurotransmitters to be mentioned here is produced in a transitional region between the midbrain and the diencephalon called the ventral tegmental area. The neurotransmitter produced by these cells is called dopamine (DA). Dopamine is also produced in other sites in the brainstem, the best-known of which is the substantia nigra (well known due to its role in Parkinson's disease). This nucleus is the source of the nigrostriatal DA system (which projects mainly onto the basal ganglia), but the system that originates in the ventral tegmental area is more important for our purposes. This is called the mesocortical-mesolimbic DA system, because it acts principally on limbic and cortical structures on the medial surfaces of the forebrain. Its main targets are the hypothalamus, nucleus accumbens (a basal-forebrain nucleus nestled beneath the basal ganglia), anterior cingulate gyrus, and amygdala. This system also projects to other structures, including the frontal lobes as a whole.

The neurotransmitters just described (as well as others that we have not discussed, such as histamine, which is sourced mainly in the hypothalamus) are called neuromodulators. This refers to the fact that the state-dependent neurotransmitter systems through which they operate exert global effects, via mass-action, over and above the existing activities of the specific pathways in the channel-dependent systems. They modulate these activities, in response to the current state of the organism. Thus, for example, all cognitive operations are affected – in a relatively global way – by changes in mood, vigilance, and waking state.

The Brain and the Inner World, Introduction to Basic Concepts. Mark Solms, Oliver Turnbull.

Our cognitive operations are affected by changes in mood... Photo by Elena.