Simply Science

ONE MAN'S VIEW OF SCIENCE

2009-05-21T09:47:00.002-05:00

One scientist, Franklin M. Harold, gave an interesting view of science in the Epilogue of his book, The Way of the Cell*. I would like to quote him: "I have come to think of science as a kind of game, whose object is to make sense of the world. Players are bound by strict rules: the imagination must ever be disciplined by reason, observation and experiment, and no cheating, please! It is the most engrossing game ever invented, one to which I and many others have happily dedicated our lives; and it has revealed much that is new, true and important. But we must never forget that the game of science is played on a board, and most of what matters most to human beings lies off the board. Science has little useful to say about good and evil, right and wrong, justice and oppression, and the strange ways of the human heart. Science can often explain what is happening, and it can sometimes forecast the future and distinguish wisdom from folly. But it provides no basis for ethical choice, nor the will to act. About what it means to be human, individual scientists often hold strong opinions; but science must be silent." *Oxford University Press, New York, 2001

A VERY MUCH MALIGNED GAS

2007-12-10T21:45:00.001-05:00

With our almost religious fervor to embrace the idea of global warming, carbon dioxide in our atmosphere is getting a bad rap. Rarely mentioned are the other so-called green house gases: water vapor and methane. With about three-quarters of the Earth covered by water, water vapor is tough to do much about. And methane is emitted by many living things notably we humans, cattle and termites.

Carbon dioxide occupies less than 0.04% of the air we breath, but has admittedly a profound effect on our planet. Without it, the average temperature of the Earth would be well below freezing. Our distance from the Sun, makes its warming effect not enough to keep us toasty. Even more importantly, carbon dioxide keeps us from starving. It is the crucial source of all our food. Plants use the sun's energy to break apart carbon dioxide and turn it into the carbon-based molecules that make up our food. Every year some 100 billion tons of carbon dioxide are converted into plant material. This provides the foodstuff that feeds every animal and human on Earth.

Unfortunately, when anything is burned for energy to drive our world--be it wood, oil, coal or natural gas, carbon dioxide is produced as a by-product. Even the slow burning of food in animal or human metabolism creates carbon dioxide. Plants convert water and carbon dioxide into sugars and starches and give off oxygen as a by-product. We and other animals eat plant tissues and burn them with oxygen for energy while exhaling carbon dioxide. This is how nature preserves the cycle of life.

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How Telescopes and Binoculars Work

2007-01-29T13:21:00.000-05:00

The closer an object is brought to our eyes, the larger it appears. There is a limit, however, to how close to our eyes we can bring an object and still see it clearly. This is about 10 inches. Placing a lens between the eye and an object allows the object to be moved closer than 10 inches. The object then appears larger as experienced by anyone who has used a so called magnifying glass. To magnify an object greatly, would require that it be very close to the eye. This may not be practical in most cases and impossible in the case of an astronomical body or a bird in a distant tree. Here is where the optical scheme used by microscopes, telescopes and binoculars can help us out. The curved surface of a glass lens can bend light rays coming from an object in a coherent way so as to form a small image or "picture" of the object at a fixed point within the tube of the optical device. Although the image "hangs" in mid-air, it nevertheless is real. It can actually be seen by placing a white card at the image (focal) point within the tube. Once an image is formed by the objective lens, a second lens (or lenses) called an eyepiece is used to enlarge it. The eyepiece allows the eye to come very close to the image while keeping it at a comfortable distance. By selecting eyepiece lenses of different surface curvature, almost any magnification can be obtained. The actual magnification is determined by the focal length of the objective lens (distance from lens to image) divided by the focal length of the eyepiece. A 200 inch focal length objective lens used with a 1 inch focal length eyepiece produces a magnification of 200X.

What Do Calories Taste Like?

2007-01-28T10:12:00.000-05:00

Many weight conscious people are concerned about their daily calorie intake. But what does a calorie taste like--sweet, sour or salty? This, of course, is a nonsensical question because a calorie doesn't have a taste because a it is not a substance, but a unit of measure. In this nutritional context, it is the measure of the energy content of a food. Technically, a calorie is defined as the amount of heat energy it takes to raise the temperature of one gram (about 1/30th of an ounce) one degree Celsius. A nutritional calorie is defined to be 1000 times bigger (kilocalorie) than the standard one and is frequently capitalized Calorie. --- All forms of energy can be converted from one form to another--heat to electrical, for example, or electrical to light or mechanical energy. Take a jelly bean, for example. It weighs about 3 grams and is almost 100% sugar. If one gram of sugar is completely burned, it would produce 4.1 Calories of heat energy. Therefore, one jelly bean is equivalent to 12.3 Calories. This is enough energy to keep a 60 watt light bulb operating for 14.3 minutes. By comparison, a can of beer or a donut will keep the lamp lit for nearly three hours. The Calories and thus the energy in a quarter pound hamburger will keep the lamp burning for almost 20 hours. --- All human activities expend energy--some activities more than others. Just sleeping uses some 1.2 Calories per minute, standing 2.0, walking 3.7, bicycling 7.7 and swimming a walloping 13 Calories per minute. As food is metabolized (burned) in our bodies, the energy released drives the chemistry of our muscles to produce mechanical motion. Some of the energy, of course, is lost to the environment in the form of heat.

SCIENCE--What's It All About

2006-08-11T14:23:00.000-05:00

It is often asked what is science and how does it work. Lots has been written on this subject, but the clearest and most concise explanation I have run across is by Dr. Eric Chaisson in his recent book, Epic of Evolution*. He says “The scientific method normally works like this: First, gather some data by observing and object or event, then propose and idea to explain the data, and finally test the idea by experimenting with Nature. Those ideas that pass the tests are selected, accumulated, and conveyed, while those that don’t are discarded. In this way, by means of a selective editing or pruning of ideas, scientists discriminate between sense and nonsense. We gain an even better approximation of reality. Not that science claims to reveal the truth--whatever that is--just to gain an increasingly accurate model of Nature."

*Colombia University Press, 2006.

Electricity/Magnetism

2006-06-03T12:15:00.000-05:00

Electricity is one of our most important forms of energy. It illuminates are nights, powers our factories and heats many of our homes. Like so many other very familiar and ubiquitous things around us, we sometimes fail to appreciate their origin and their relationship to other natural things. Electricity, like other forms of energy, obeys the basic physical principle that it cannot be created or destroyed only changed from one energy form to another. So what is it and how do we produce it?

First of all, electricity is the energy resulting from the movement of charged particles. These particles are the building blocks of the atoms of all things--rocks, air and are own bodies. Two of the three particles that constitute atoms, electrons and protons, have a property in addition to their mass called charge. It happens that the charge on these two particles is different, so scientists, for want of a better term, arbitrarily have called the charge on the electron negative and the one on the proton, positive. As you may remember from high school science, like charges (two negative or two positive) repel each other and unlike charges (a positive and a negative) attract each other. Luckily, the total number of positive and negative charges in atoms are normally equal. Therefore, the effects cancel each other and things are electrically neutral, i.e. appear to have no charge.

If by some means electrons are dislodged from their atoms (relatively easy in metals that is why they are good conductors of electricity) and get them moving, an electric current results. Of course, it takes countless billions of electrons moving together to accomplish any real work. A battery, by chemical action, strips some electrons from atoms and delivers them to one terminal while atoms now with a net positive charge remain at the other terminal. If an external conducting path is provided, a current will flow. Electrons will move toward the positive terminal attempting to restore the electrical balance. An electric current continues to flow until the battery chemicals are depleted. Since the current produced by a battery always flows in one direction (negative to positive), it is called direct current (DC).

The lights in our homes and businesses are not powered from batteries, but rather from the alternating current (AC) power line. The electrons in our house wiring go no where but accomplish their work by simply oscillating back and forth 60 times a second. Alternating current is created by power plant generators using the principle of electromagnetism.

Around every magnet is a field of force. That’s what every science student has seen traced out by iron filings on a surface above a magnet. If a conductor (a wire or coil of wire) is moved across a magnetic field or a magnetic field is moved in relation to the conductor, an electric current will flow in the conductor. The electrons in the conductor ‘feel’ the magnetic force and are accelerated by it. The current only flows while either the conductor or magnetic field is moving and stops when either motion ceases.

An electric generator is a device that rotates a huge coil of wire through a powerful magnetic field to create an electric current. The coil is rotated by a turbine powered from falling water, the wind, or steam generated from water by burning coal, oil, or by the heat of a nuclear reactor. As the coil rotates, the conductor moves up through the magnetic field and then down through it with each rotation. The result is that the current changes direction with each rotation resulting in alternating current.

The word electromagnetism suggests the intimate relationship between electricity and magnetism. They are like the two sides of the same coin. While a magnetic field can create an electric current, an electric current also creates a magnetic field around the conductor. A magnetic field is frequently concentrated by winding the conductor into a coil around a iron core. This forms an electromagnet which is energized whenever current is applied to the coil. Such a device in a form called a solenoid, is used to convert an electric current into a mechanical action. Solenoids operate such things as water valves in wash machines, dishwashers, etc. Solenoids in devices called relays can also remotely operate switches that can turn things on and off like your furnace .

More Than Meets the Eye

2006-02-27T16:41:00.000-05:00

Anyone who follows science even a little knows that our universe is incredibly vast. In addition to Earth and other planets circling our star, the sun, there are countless billions of other stars. These form great, rotating islands of stars called galaxies that also number in the billions. In recent years, astronomers have found that what we see in the universe may be only a small fraction of the "stuff" that exists out there. Measurements of the rotation speed of galaxies show that they are rotating faster than they should for the amount of material they contain, and should be flinging their stars out into space. In other words, the combined gravity of the galaxy's constituent stars do not have enough mass to hold the galaxy together. Since galaxies are not coming apart, astronomers were forced to theorize that there must be more stuff in the galaxies than what they see or detect with instruments. They have called this stuff Dark Matter. No one, currently, has any idea of what it is. In addition to dark matter, astronomers have discovered another cosmic anomaly. They have known for some time that galaxies are all moving away from each other as space and the universe expands. This expansion has been going on ever since the universe began with the big bang some 14 billion years ago. However, the gravitational attraction of all the galaxies for each other should be slowing down the universe's expansion. Over the past several years, astronomers have decided to measure what this rate of slowdown is. They did this by measuring two things in distant galaxies. First, the galaxy's speed of recession as indicated by their red shift--how their light is reddened due to the stretching of their light waves by the expansion of space. Second, the galaxy's distance. This is done by finding in the galaxy a particular type of star whose intrinsic brightness is known and measuring how its light is dimmed by its distance. Astronomers refer to such known brightness stars as a standard candles. The particular kind of star used in this study and occasionally found in galaxies, is called a Type Ia Supernova . When you make a graph of red shift (speed of recession) versus distance you would normally expect it to be a sloping straight line if the universe was expanding at a constant rate. If the plot curved slightly downward, the universe's expansion was slowing down as was expected. What they were surprised to find was that the plot curved upward indicating that the supernovae were dimmer than expected. That meant that the galaxies were farther away than expected, and that the universe's expansion was not slowing down but accelerating. Apparently the gravity created by all the galaxies and dark matter must be counteracted by some repulsive or anti-gravity force. What this force, termed Dark Energy, is no one has a clue. Under current thinking, the visible stuff (planets, stars, galaxies, etc.) makes up only about 4% of the mass of the universe. Dark Matter represents about 23% and Dark Energy (Einstein showed that energy and matter are equivalent) about 73%. Cosmologists have some big mysteries to solve, so stay tuned!

A View From Planet Earth

2005-12-16T10:20:00.000-05:00

Our home in the universe is a planet called Earth. It is a rocky body that is nearly three-quarters covered by water and is enveloped in a gaseous atmosphere. The Earth has been likened to a spacecraft with the oceans and atmosphere as part of our life support system. Space ship Earth is hurtling us though space at nearly 1200 miles per minute on yearly 600 million mile trip around our star, the sun. While orbiting the sun, the Earth also spins on its axis completing a rotation once each day. As we turn toward and away from the sun, we experience day and night. During the day, our view of the universe is hidden by the sun’s glare. Instead, we see a brilliant sun against the blue sky. Why is the sky blue? Because that is the color of air. Light from the sun consists of all the colors of the rainbow, but as it passes through the atmosphere, the molecules of air are just the right size to scatter the blue light in all directions making the sky look blue. The remaining colors of light come through the atmosphere giving a yellowish color to the sun when high in the sky, and reddish color when the light must pass through even more atmosphere as the sun nears the horizon. As your particular locale rotates away from the sun and enters the Earth's shadow, darkness descends and you see hundreds of other suns. Each twinkling star is a brilliant sun, many even larger and brighter than our own. All are reduced to specks of light in the night sky because of their enormous distances. When first observing the night sky from a dark area, it may appear as a rather confusing panorama of stars, fixed and unchanging. However, as with most things in nature, a more careful observation shows intricate differences and subtle changes that become more and more intriguing as you make keener observations and learn to understand more of what you are seeing. For example, even the most non-critical observer notices that the stars are not all the same brightness. The brightest stars are, in fact, more than 100 times brighter than the faintest ones the eye can see. In about 130 BC the Greek astronomer, Hipparcus, developed a five step brightness or as he called it magnitude scale. It begins with what is called 6th magnitude for the faintest stars. Then each successive magnitude step is 2.5 times brighter than the previous step. The brightest 1st magnitude stars are, therefore, 100 times more brilliant than those just visible to the naked eye--the 6th magnitude stars. Modern astronomers have had to extend the magnitude scale because more precise measurements show that many of the really bright stars are actually brighter than 1st magnitude. Some approach zero magnitude, and four require that the scale be extended toward negative numbers. The brightest star in the sky, Sirius, for example, has a magnitude of -1.42. Although 6th magnitude is still considered the limiting visual magnitude, in reality it is more like 3 or 4 in many urban areas because of light pollution. Why are some stars brighter than others? The obvious explanation is that the stars are not all equally distant. The fainter stars, of course, being the farthest away. However, this is not the only reason. Astronomers have found that stars differ in their real brightness or luminosity because of their different sizes and temperatures. Two stars may appear of equal brightness even though their distances are widely different only because the more distant star is larger. Take, for example, the brightest star in the summer sky, Vega, and the nearby star, Deneb. They appear of nearly equal brightness, yet Deneb is more than 60 times as far away as Vega. To appear as bright as Vega, Deneb’s true luminosity is some 3000 times that of Vega. How far away are the stars? The nearest star, of course, is the sun. It appears larger and brighter only because it is relatively near to us--only 93 million miles away. Because stellar distances are so incredibly large, astronomers find it more convenient to describe distances in terms of how long it takes light to reach us from the star. Light travels at the speed of 186,000 miles a second--a distance more than seven times around the Earth. It takes light 1.25 seconds to reach us from the moon, about 8 minutes from the sun, and 4.3 years from the next nearest star, Alpha Centuri. Astronomers would say that Alpha Centuri is 4.3 light years distant. Some have trouble with this idea of expressing distance in units of time. But we frequently do the same thing in casual conversations: " I live only 10 minutes from the mall." What we mean is that traveling by car at some reasonable speed it takes only 10 minutes to reach the mall. How great are the distances between stars? To get an impression of these distances and the immense emptiness of space, we can scale down the distances to ones more familiar. Let the sun be represented by the size of a green pea. The Earth, a hundred times smaller, then becomes a tiny grain of sand about 2.5 feet away. The most distant planet, Pluto, is an infinitesimal speck almost 90 ft. distant, and the nearest star is represented by another pea at a distance of 112 miles! As you look up at the starry sky, another more subtle aspect of the stars that may go unnoticed. It is that stars are not all the same color. Pastel hues from red-orange, yellow, through white and blue can be seen. Why these color differences? Because the stars have different temperatures--an iron bar heated in a forge that glows red is cooler than one that glows white hot. The stars are huge globes of hot gases that are heated by nuclear furnaces in their cores. The temperature and, therefore, the star’s color depends upon its size and the amount of material it contains. Our sun is a yellow star with a surface temperature of about 6000 degrees. The famous constellation of Orion, seen in Winter sky, includes stars of three colors. There is the super giant red star, Betelguese, the white star Rigel, and the blue star marking the top end of Orion’s belt. These stars have temperatures ranging from 3000 to 40,000 degrees. *The above was part of a Monthly Observatory Nights talk entitled Astronomy From the Backyard that I gave at the Harvard-Smithsonian Center for Astrophysics, Cambridge, MA on August 15, 1996.

Monitoring Solar Activity

2005-10-27T09:29:00.000-05:00

Our Sun is a very active star. It not only emits energy as visible light that makes life possible here on Earth, but also radiates infrared, ultraviolet, microwave, x-ray, and gamma ray energy. Luckily, most of the more dangerous radiation is blocked by our atmosphere. Astronomers constantly monitor the Sun using detectors on satellites as well as on ground based radio and optical telescopes. The American Association of Variable Star Observers (AAVSO) has a program for monitoring what are called Sudden Ionospheric Disturbances (SIDs) caused by x-ray and ultraviolet flares on the Sun. A SID is a change in the upper atmosphere of the Earth due to the impact of solar flare radiation. It results in making the ionosphere more ‘reflective’ for very low frequency (VLF) radio waves, and, therefore, to strengthen the reception of these radio waves. SID monitoring involves a simple antenna and radio receiver tuned to a distant VLF transmitter. Conveniently, the military operate such transmitters for their own purposes that amateur astronomers like myself can use to record SID activity. I have recently been honored to be recognized by the AAVSO as a SID observer who has contributed SID data reports for over 40 months. My SID detection system consists of a small wire loop antenna and a VLF receiver tuned to a 24 kilohertz transmitter operated by the US Navy in Cutler, Maine. The output signal strength of this station is measured once every 30 seconds by a computer that runs every day during daylight hours. When a UV or x-ray flare occurs on the sun, the radio signal suddenly increases and then fades within several minutes. A computer program plots this change in signal strength versus time as a graph and stores it as a file. Once a month, I review these stored graphs and report to the AAVSO the SIDs that I have recorded. I am proud, along with the group of a dozen or so other observers around the world, to make this small contribution to solar astronomy.

Gravity Express

2005-10-18T09:28:00.000-05:00

"When I was in high school", writes physicist, A. Zee*, "I read about how gravity might be exploited to create a new mode of travel. Suppose a tunnel could be dug straight down through the center of the earth to the other side. Look down into it. Scary! An apparently bottomless pit. We have bought our ticket and now we are invited in. We take a deep breath and we jump." "Whoosh! We fall straight down, just as Alice once fell into the rabbit hole. We go faster and faster. It is that falling dream come true! We go rushing past the center of the earth. The moment we go past the center, gravity starts to act as a brake. It tries to pull us back to the center. We start to slow down. Will our momentum carry us through? Yes! Provided there is no friction, we would just make it to the exit hole on the other side. We would also need help getting out of the hole, lest we fall right back in." "In practice, there is friction, and we need a little boost to get us to the end. Of course, we would also need to be inside a capsule strong enough to withstand the searing heat at the center of the earth, not to mention the lightning speed we will get up to as we zoom past the center." "Since we know the strength of the gravitational force, we can easily figure out how long the trip would take. It turns out to take forty-two minutes! No airplane with current technology could possibly get you there that fast. Better yet, no fuel is needed for this ’gravity express.’ We just let gravity do its thing." "You are suspicious. What is the catch? There is no catch, aside from the expense and engineering difficulty of building a heatproof tunnel that would not collapse through the center of the earth. The physics is perfectly sensible. Gravity always is trying to pull us down; we will just let it." *An Old Man’s Toy--Gravity at Work and Play in Einstein’s Universe, Macmillan Publishing Company, N.Y., 1989.

Looking At Matter

2005-09-09T10:00:00.000-05:00

Our universe consists of an enormous amount of space and a sprinkling of more substantial stuff that we can see and has solidity and weight that we call matter. Even though no one really knows what matter is, scientists are quite adept at describing its structure and predicting its behavior. It is obvious to everyone that matter is assembled into many different things from rocks to people to stars to galaxies. It has been the quest of science to discover and understand the underlying commonality of all these things. What is the basic stuff, and how does it interact to form the immense and wonderful variety of the things we know and the changes they undergo. What science has found is that all objects matter forms are made up of countless, incredibly tiny bits of matter we call atoms. On the submicroscopic level, our world is a virtual sea of atoms, and like a sea the atoms are in constant motion--vibrating, rotating, and whizzing about. When a collection of atoms bind together in a relatively rigid structure, they form things that feel hard, appear solid, and have noticeable weight. We can’t see through solid objects because the atoms are packed too closely together allowing little space for visible light to get through. Even when atoms are locked together in a solid, they haven’t totally given up their movement. They still dance about in position. In fact, when we touch an object and feel its warmth, we are feeling the vibration of its constituent atoms. What we call temperature is simply a measure of atomic motion. The hotter the object, the more its atoms are vibrating. At temperatures above absolute zero (-273 degrees), atoms are always in motion. When atoms are more loosely bound to each other so that they can collide, slide and move over and around each other, they form squishy stuff we call a liquid--the most ubiquitous example of which is water. Many liquids are transparent because the atoms are far enough apart providing space for light to pass through them. The average atomic motion in a liquid is higher than in a solid so that individual atoms occasionally have enough speed to break away from the mass of the liquid. In an open container, a liquid slowly disappears or evaporates. The higher the temperature of the liquid, the more agitated the atoms become and evaporations increases. The freest atoms of all are those that form the gases like those in air. The atoms are far enough apart that they feel little attraction for each other. They move about with the speed of bullets, colliding and bouncing off each other. The gases in the air, for example, are ordinarily transparent and feel tenuous and weightless until we feel a breeze or the winds of a storm. Actually, the bombardment of air atoms create a pressure of about 14 pounds on every square inch of our bodies. Substances differ from one another in other ways than their form as solid, liquid, or gas. There are countless different solids--rocks, metals, plastics, skin, bones, etc. If they are all made up of atoms, why do they differ so in their characteristics? One reason is that all atoms are not alike. There are 92 different naturally occurring atoms of which about half make up most of the things we are familiar with. When a substance is comprised of only one kind of atom such as a piece of iron, we call that substance a chemical element. Since there are 92 different atoms, there must be 92 chemical elements. Some are rare like gold and silver and others like nitrogen, iron, silicon, aluminum, and oxygen are very common. In fact, hydrogen is the most plentiful element making up more than 90 percent of the universe. Elements common to all living things including ourselves are carbon, oxygen, hydrogen, nitrogen, sulfur and phosphorus. The vast variety of substances around us owe their existence to the fact that atoms not only have a tendency to hook up with each other, but also with different atoms. In so doing, a new substance emerges that often has totally different characteristics. When atoms of the poisonous gaseous element, chlorine, are mixed with the metallic element, sodium (a dangerous material itself because it combine explosively with water), common table salt is formed. A tiny spark causes a mixture of the gases hydrogen and oxygen to combine explosively to form water. The heat of the spark, accelerates a few of the oxygen and hydrogen atoms to collide violently enough to stick together starting a chain like reaction that ends up with all the atoms involved combined in the form of water. It is the interaction of atoms and their ability to associate into complex structures that produce the world that we know. Learning how and why these interactions take place provides the basics upon which to build and understanding of the great bulk of the happenings in our world and the whole universe, but that’s a story for another time.

Zero Gravity--No way!

2005-08-05T09:36:00.000-05:00

Frequently you will hear news commentators and others use the phrase zero gravity when covering space events. There is no such thing as zero gravity. Everything from elephants to rocks to spacecraft have mass and are attracted to everything else that has mass by a gravitational force. Isaac Newton showed that this force is proportional to the masses of the two objects and decreases by a factor of the square of the distance between them. The mass of all material bodies, whether on Earth or in space results in inertia. It thus takes a force to start and object moving or to change its motion. What a spacecraft or its inhabitants do not have in space is weight. For weight comes from resisting the pull of gravity. You have weight because you are being pulled against the floor, and the floor keeps you from falling any further. If you bungee jump off a bridge, you will be weightless briefly because you are in free fall. The force of gravity is constantly acting on anything in orbit, be it the moon, the space shuttle or other satellite. The orbiting satellite stays there because the downward force of gravity pulling the satellite toward the Earth counterbalances the forward momentum of the satellite given to it by the launch rocket. The satellite's momentum continues even after the rocket stops thrusting and falls away. Without the gravitational pull, the satellite would fly off into space. Without friction or drag in airless space, an object can remain in orbit nearly indefinitely. The Moon has been orbiting the Earth for billions of years with nothing pushing it.

Let There Be Light

2005-07-13T09:12:00.000-05:00

Most of the beauty and wonder of the world is conveyed to us through our eyes and our sense of sight. To know the world through this medium is one of the most marvelous of human faculties. It is made possible because the universe is pervaded by radiant energy, a portion of which we call visible light. Light energy from the sun or some artificial source reflects off of objects and is imaged by our eyes and brain allowing us to see shapes, textures, and colors. Other radiant energy like infrared and ultraviolet is not sensed by our eyes. Infrared is sensed by our skins as warmth while ultraviolet radiation initiates the tanning process to protect us. Although we do not have biological sensors to detect all radiant energy, scientists have created electronic sensors to detect and measure the whole gamut of radiation from gamma and x-rays through ultraviolet, visible, infrared to microwave and radio waves. All of these are not fundamentally different from each other or from that we call visible light. In fact, they form a continuous band of radiation which differs only in energy content from one end of the band to the other. Scientists refer to it by the esoteric sounding name, the electromagnetic spectrum. Visible light, like the other types of radiant energy, comes from atoms. Atoms are always jostling around and when a collision gives an atom extra energy, the atom is said to be in the excited state. This is an unstable condition and the atom quickly reverts to its normal state by releasing the extra bit of energy in a burst of radiation. Think of the calm surface of water in a backyard bird bath. Drop a pebble into the water and note the ripples that expand out from where the pebble hit. The energy of the falling pebble hitting the water at one spot was dissipated as a wave movement over the surface of the water. Similarly an excited atom rids itself of the access energy by radiating a light wave--a wave that travels at the incredible speed of 186,000 miles per second. Light from a light bulb’s hot filament consists of countless light waves being released by billions of excited atoms. One important difference between a light wave and a water wave is that the light wave needs no medium in which to make the wave. It can travel through the vacuum of space. The reason for this is that the light wave is an effect not physical substance. An excited atom is one in which one of its negatively charged electrons has gained energy and moved farther from the atom’s nucleus. Every charged particle can be thought of as having an invisible field about it--a field of influence over which the repulsive or attractive effects of the charge can be felt. This field, theoretically, extends out in all directions to the ends of the universe although practically its strength decreases rapidly as the distance from the particle increases. Therefore, the space within and between atoms throughout the universe can be looked upon as permeated with a complex grid made up of the combined fields of all the charged particles in the universe. It is the energy that is transferred as a wave disturbance through this field that constitutes light and all radiant energy. The wave is more complicated than explained here because it has two components; one electric and the other magnetic and this is why all forms of radiant energy is described as electromagnetic radiation. Scientists characterize the energy content of electromagnetic radiation in several ways. The most common way is to speak of its wavelength--the distance between two crests or two troughs of the wave. Low energy radiation like radio waves have wavelengths measured in meters. While much higher energy visible light has wavelengths of less than a millionth of a meter. Since all waves travel at the same speed, longer wavelengths have lower frequencies (ripples per second) while shorter wavelengths have higher frequencies. In any case, the only difference between one type of radiant energy and another is its wavelength (or frequency). Electromagnetic radiation is a continuous spectrum of wavelengths from the high energy gamma rays at one end through x-rays, ultraviolet, visible light, infrared, microwaves to low energy radio waves at the other.

Energy--What is it?

2005-06-20T08:55:00.000-05:00

One of the most basic characteristics of our world and the universe around us is that of motion and activity. Change is everywhere and in everything. Movement is pervasive. On the large scale of things, living beings and inanimate objects roam over the surface of the Earth. The Earth circles the Sun, the Sun like billions of other stars revolves around the center of our galaxy, while our galaxy along with countless others careens through space. On the submicroscopic scale, the atoms and molecules that are the building blocks of all larger bodies are in ceaseless state of agitation. If there was no motion, our universe would collapse and cease to exist. Things move because energy is expended. Things interact and change because they exchange energy with each other. Every known activity including all processes within living things can be described in terms of energy interchanges. Energy is ubiquitous--it makes the sun shine, the wind blow, wheels turn, water flow and fire burn. It may rest quietly in a gallon of gasoline, a jelly donut, a compressed spring, or in a dammed-up river. You have to invest some energy to do work--push a shopping cart, lift a book, or pedal a bicycle. Whatever work is done, energy is used. The faster the work is done, the more energy must be applied. We cannot make energy or destroy it; we can only use it. The total amount of energy in the universe is the same now as it was at the beginning of time. Only its distribution has and is changing. Although we use the word energy quite casually and freely, does energy really exist? Not really, its not a thing like matter that has substance, weight and can be seen. Instead, it is a concept--a convenient way of thinking about and describing the effect of forces acting on matter to produce motion. It is an accounting system scientists use to keep tract of the transfer of movement between objects that has proved to be incredibly powerful in explaining our natural world. The idea of energy allows numerical values to be assigned to movement and change allowing us to track mathematically the interaction of things like their change in position, velocity, and the distances they move. It is because energy is conserved that it is such an important and useful concept. The fact that nature maintains the amount of this abstract quantity at a constant value through its many possible transformations from one form to another is quite amazing and useful from a practical point of view. The very essence of science is the belief that the total quantity of energy in the universe is constant and is conserved through its many transformations. Why movement or energy is at the essence of things is unknown. All science can say is that is the way things are and continue to use the concept of energy to probe, describe and shape our world.

Science--Today's Mythology?

2005-06-08T09:37:00.000-05:00

Ancient peoples created all kinds of stories to explain natural occurrences that they did not understand. We now refer to them as myths. Could modern man have his myths also? Could it be called science? To be sure, our scientific world view is probably the best of which we humans are capable. Scientific knowledge is more comprehensive, detailed, and accurate to judge from the fact that it can make predictions, and we can use our understanding of things to modify our environment--go into space, create new tools, medicines, etc. However, the scientific description of things should not be taken too literally because the real world out there may not be anything like we imagine. For example, our eyes can only see a very small fraction of the light out there--radio waves, microwaves, infrared, ultraviolet, x-rays and gamma rays are all forms of light we cannot see, but they are out there in the universe. What would things look like if we could see with radiation other than visible light? The chair you are sitting on feels very solid, but in reality it is about 99% empty space. What you feel as solidity is the force of electrical repulsion between the atoms of the chair and the atoms of your bottom. And these atoms are mostly nothing--tenuous energy waves with no real substance. Things look solid only because of the coarseness of our vision. The point is that the world of things and events are our brain's interpretation of information it receives through our senses and may not bear any resemblance to the real world out there. Our bodies and brains evolved to live, survive, and reproduce like all living things, not necessarily to explore our physical world to figure out how it works. Consequently, we have invented this great myth of science to try to make sense of things. We don't know what is really real out there and what is the creation of our minds. For all anyone knows, the entire outside world could be a dream. My favorite modern philosophical thinker, Dr. Deepak Chopra, puts it very well in his The Book of Secrets. To paraphrase him, you are not in the world; the world is in you. We are creating every perception that we take as reality. Perception is the world; the world is perception. He illustrates this with the following: Hold a red rose in front of you. Inhale the fragrance and say to yourself: Without me, this flower would have no fragrance. Take in the glowing crimson color and say to yourself: Without me, this flower would have no color. Stroke the velvety petals and say to yourself: Without me, this flower would have no texture. Realize that if you subtract yourself from any sensation--light, sound, touch, taste, or smell--the rose and the world would be nothing but atoms vibrating in a void.

Gravity and Our Earliest Beginnings

2005-05-30T14:50:00.000-05:00

The our in he the title should more accurately be the universe’s earliest beginnings because we are relatively newcomers to the scene. Everyone has heard that everything we see today--all matter, energy, space and time--sprang into existence some 13 billion years ago. The event was referred to as the Big Bang by a British scientist who was ridiculing the idea, and the name has stuck. Although difficult for us to fathom, the evidence for the Big Bang is very solid. Who says nature has to be mindful of human sensibilities and logic. The Big Bang was an unbelievably high temperature, high energy event that began from a single point and rapidly expanded. As the initial energy ballooned outward creating more and more space, it slowly cooled. Matter began to crystallize out as simple atoms of primarily the gases hydrogen, and helium. Matter can be thought of as frozen energy, and the two are equivalent and interchangeable as Einstein has shown. Notably in this early universe, there was little of the stuff of which we or our Earth are made. These elements had to be cooked in stars much later in time. Most popular accounts of the Big Bang rarely mention that certain other things were also created at this time. Namely, the rules of the game. These took the form of four forces that were to shape and control the newly formed universe for the rest of time. Scientists refer to them as gravity, electromagnetism, the strong and weak nuclear forces. These forces determine everything that happens in our physical world. Why they exist and act as they do is not clear--they just are. Although all are active in our universe, only two are normally encountered by we humans. They are gravity and electromagnetism. Gravity holds our feet to the Earth, gives things weight, causes rain to fall, powers the cycle of tides, pulls the stuff of planets and stars toward their centers to form spheres, and holds planets in orbit around the Sun. Gravity rules on the large scale when massive bodies like planets stars, and galaxies are involved. Electromagnetism, on the other hand, rules on the small scale. It is the electrical force that binds atoms and molecules together to form all the natural and man made things we know including our own bodies. This force is responsible for all the properties of things such as their shape, solidity, texture, and color. Of the four forces, gravity is the weakest. The fact that we walk erect against the Earth’s gravity pulling us down testifies to the fact that the electromagnetic force is much, much stronger. Nevertheless, if it were not for the influence of gravity in the post Big Bang era, our universe would consist of nothing more than a homogenous mixture of essentially hydrogen and helium expanding probably forever. No stars, no planets, no people would have ever come about. Luckily, at least for us, the universe did not remain homogenous. Instead, regions developed that were cooler and more dense. These regions would attract more matter through their greater gravitational pull, increasing the density even more. Over eons of time the universe began to break up into ever growing individual clouds of hydrogen. As they became increasingly more massive, their gravity began to pull the clouds into a spherical shape. Their internal temperatures began to rise due to the compression of the gas by gravity. When their core temperatures reached some millions of degrees, a nuclear fusion of hydrogen into helium was ignited with the release of tremendous amounts of radiant energy in all forms including visible light. The first stars was born! This set off a new era in the expanding universe that resulted in the creation of all the other chemical elements through the birth, evolution and death of stars, and the subsequent birth of new stars from the ashes of the old. The coalescing of these elements formed planets orbiting many stars, and at least around one third generation star, the Sun, life forms began, evolved, and culminated in humans that figured all this out.

Canned Sunlight

2005-05-17T21:41:00.000-05:00

The concept of energy has always fascinated me, and this web log will discuss aspects of it often. Everyone realizes that the ultimate source of energy for most of mankind’s activities on Earth is our Sun. The exceptions are nuclear energy and hydrothermal energy which results from radioactivity deep within the Earth. A friend of mine who has no knowledge of science or any interest in it, made a comment while sitting before my fireplace "those flames are ancient sunlight being released from the wood." I found it a remarkable observation coming from him, and, of course, he was absolutely right. All our fossil fuels, coal, wood, petroleum, and natural gas, result from solar energy stored in now fossilized ancient plants. These plants used solar energy to combine the simple ingredients of carbon dioxide from the air and water from the soil into more complex hydrocarbon molecules that make up our fossil fuels. Energy must be used to create more organized things (hydrocarbons), and is released again when these organized things are broken down again by combustion. This is nature’s way, and we call it the law of conservation of energy. Getting back to the Sun. Why is it hot and where did the energy which it so freely radiates come from? If you are science savvy, your immediate answer might be the nuclear fusion in the Sun’s core. Yes, there is a controlled hydrogen bomb like explosion going on continuously in the Sun’s center. Atoms of hydrogen are fused into those of helium with the release of lots of energy. In fact, this nuclear fusion actually keeps the Sun cool. The Sun, like all stars, condensed out of an immense, diffuse cloud of cool gas. As the cloud collapsed toward its center under the pull of its own gravity, the potential energy of the gas is converted into increasing velocity of its atoms resulting in higher and higher temperatures. Eventually, the core temperature becomes hot enough to kindle thermonuclear reactions. Now, the radiation pressure from nuclear burning balances the force of gravity and stops the Sun from contracting further--preventing it from getting any hotter. So the initial gravitational collapse of the Sun is what makes it hot.