Speeding Up And Slowing Down---What’s The Deal With The Speed Of Light?
The science world is in tentative shock after it was announced that CERN (European Organization for Nuclear Research) scientists had recorded subatomic particles traveling faster than the speed of light. This finding, if true, could overturn a fundamental law of physics.
SCIENCE IS FUN AS WELL AS EDUCATIONAL -
I heard my favorite speed of light joke on the Tonight Show with Jay Leno back in 1999 after scientists announced they had managed to slow down the speed of light to 38 miles per hours. That’s a virtual crawl---38 miles per hour is twenty-million times slower than the “normal” speed of light, a blazing 186,282 miles per second in a vacuum (671 million miles per hour).
The Leno joke at the time was that scientists had succeeded in slowing the speed of light to 38 miles per hour by shooting a laser through a Post Office. This joke was well appreciated by local Postal employees who actually collect and “post” Post Office jokes (just as nuns and priests are connoisseurs of Catholic jokes).
The slowing down of light-speed (in 1999) was accomplished by a Harvard University physicist, Lene Hau, and her scientific team at the Rowland Institute for Science, a private, nonprofit research facility in Cambridge, Mass., endowed by Edwin Land, the inventor of Polaroid “instant” photography.
Very simply stated, a series of specially-engineered laser beams were passed through a “Bose-Einstein condensate”---a substance which had been postulated but was not technologically possible to make until 1995 because it involved creating vacuums hundreds of trillions of times lower than the pressure of air at the surface of the Earth, and temperatures nearly a billion times colder than interstellar space. Such temperatures are within a few billionths of a degree of absolute zero (minus 459.7 degrees F), where atoms have almost lost their energy and don’t move around much at all. Anyway, shooting light through this condensate slowed it down to 38 miles per hour.
Slowing down light has potential practical applications for sending data, sound and pictures in reduced space and using less power. The results from Lene Hau's experiment could be used to create new types of laser projection systems and night vision cameras with power requirements a million times less than presently possible.
But Hau, a research scientist at both Harvard and the Rowland Institute, said of the experiments to slow light: "We did them because we are curious about this new state of matter [Bose-Einstein condensate]…we wanted to understand it, to discover all the things that can be done with it."
After much work and preparation, says Hau, "…the results finally exceeded our expectations. It's fascinating to see a beam of light almost come to a standstill."
Okay, slowing down light is one thing---but speeding it up was considered impossible even for Nature.
SMASHING THINGS TO PIECES -
It’s got to be one of the oldest acts of curiosity in Humankind. Even chimps and monkeys have been documented using rocks to smash things like nuts---apparently true “cultural adaptations“ because not all populations of a given species engage in such acts. Bird also drop shellfish onto rocks to break out the meat inside. I can just picture the first proto-Humans smashing two rocks together only to find some of the broken pieces to be very sharp and useful tools.
Scientists today propel very tiny subatomic “particles” for long distances at near light-speeds---basically, to see what happens. In some cases the flying particles are smashed into each other (hence the term “atom-smasher”) to bust them up and see how matter is put together on the most fundamental level. Scientists like to see what flies off when fundamental particles are broken up or “smashed.”
Sometimes particles are just shot from one end of a particle-accelerator to the other to see what happens...to determine the nature of that particle. It was during such an experiment to send neutrinos underground from the CERN particle physics lab in Geneva to the Gran Sasso in central Italy that a recent possible faster-than-light event occurred. This experiment had been underway since 2006 and was searching for evidence of neutrino mass, which has important implications for particle physics and cosmology.
In some experiments the particles are directed at each other in focused beams. The accelerated particles are held in their precise course by huge, powerful magnets. In the recent event, where faster-than-light speeds may have been detected, the neutrinos were fired into “bricks” of photographic film interleaved with sheets of lead.
Visitors to these facilities speak of them as having an aura like “cathedrals” or grand “works of art.” You know, lots of patterns formed by colorful wiring, gigantic electromagnets and other components built on imposing scales.
THE STRONG FORCE -
The reason such huge machines are required is that the forces holding matter together at the atomic level are so immense that they were only “released” or “relaxed” by the tremendous heat that occurred during a very split-second at the very beginning of the Big Bang. Thereafter, matter rapidly “condensed” into the more recognizable forms we call atoms and subatomic particles.
As the universe continued to expand and cool, the common particles began to form. These “baryons” include photons, neutrinos, electrons and quarks---the building blocks of matter and life we enjoy today. As the universe continued to “cool” (to around 3000 billion degrees Kelvin) and expand even more, a fundamental transition began---likened to the “phase transition” of water turning to ice. Composite particles such as protons and neutrons (components of the nuclei of atoms), called "hadrons," became the common state of matter after this transition. But no forms of matter any more complex than that could take shape at these still extremely high temperatures. Lighter particles which existed, called leptons, were prevented from reacting with the hadrons to form the more complex states of matter. These leptons, which include electrons, neutrinos and photons, were soon able to join with hadrons to form atoms that would define present-day common matter.
There is much more to this early process, but the point is that studying how the Universe exists today makes it possible to learn about its past. Science is attempting to trace the evolution of fundamental particles of the Universe right back to the Big Bang. By the study of simple atoms science can make educated guesses as to how they formed originally. And one way to study these particles is to accelerate them to near light-speeds and smack them together.
This is the stuff of “high energy physics“---the reason why scientists are trying to bust up very small particles into even smaller particles is to learn what it was like when the very early Universe was so hot that particles were not “bound” together as they are today. The energy (heat) of the initial stage of the Big Bang was higher than anything currently accessible in particle accelerators here on Earth. Which is why bigger and bigger particle accelerators are called for.
“…MATTER---WHAT DOES IT MATTER?” - Homer Simpson
Even at “rest,“ matter and energy are really different forms of the same thing---matter can be turned into energy, and energy into matter. That was another of Einstein's great insights.
It is the “strong force“ that holds matter together at subatomic levels. It is the strong force that holds together the quarks that make up the protons and neutrons that make up the nucleus of an atom. The strong force works only at very close distances within atomic nuclei but is extremely powerful. For instance, if we could actually release it, the amount of energy in 30 grams of hydrogen atoms would be equivalent to burning hundreds of thousands of gallons of gasoline!
The total energy contained in a full kilogram of water and its oxygen atoms approaches the energy released by burning around 10 million gallons of gasoline!
But much of this is “binding energy”---the immense energy required to hold subatomic particles together at their cores. The only way for all the energy to be released from say, a kilogram of water, is for the water to be totally annihilated. This process involves the complete destruction of matter, and occurs only when that matter meets an equal amount of antimatter ---a substance composed of mass with a negative charge.
This hints at why nuclear energy plants (using other fuels) are so powerful and efficient (although high-priced and risky). However, nuclear plants are not 100 percent efficient and do not totally annihilate their fuels---which is why we have to worry about nuclear waste left over after the “burning” process.
The energy equivalents of matter (or, more precisely, “mass”) are dealt with in Einstein’s famous E=MC squared equation. Although referring to “mass” at rest, E=MC squared can include the kinetic energy developed when the body is moving rapidly---called “relativistic mass.” Thus the importance of the speed of light---tremendous energy is developed in even tiny amounts of mass when accelerated to high velocities.
The “relativistic” mass is defined as the ratio of the momentum of an object to its velocity. Relativistic mass depends on the motion of the object. If the object is moving slowly, the relativistic mass is nearly equal to the rest mass and both are nearly equal to the usual Newtonian mass.
If the object is moving quickly, the relativistic mass is greater than the rest mass by an amount equal to the mass associated with the kinetic energy of the object. As the object approaches the speed of light, the relativistic mass grows infinitely, because the kinetic energy grows infinitely and this energy is associated with mass. Still, even the smallest mass is considered to be held to a speed-limit---the speed of light. The speed of light (and all electromagnetism) is something scientists thought they had calculated with great precision. And maybe they have!
BREAKING THE UNIVERSAL SPEED LIMIT -
Okay, so what does the maximum speed at which light can travel have to do with anything? Objects moving at near the speed of light follow physical laws which are radically different from the laws of Isaac Newton. And the maximum speed at which light can travel establishes an upper limit to the speed of any object, according to Einstein’s special theory of relativity.
The maximum speed of light has been considered a universal constant for a century or so. Much of modern physics, cosmology and astronomy are based on the insight by Einstein that the speed of light is constant irregardless of the movement of its source or of the observer.
Thus, the very recent, very preliminary and very tentative finding---that a neutrino (particle) has, within narrow statistical probabilities, exceeded the speed of light during a 454-mile underground trip from Geneva to Italy---is astounding news from the European Organization for Nuclear Research, or CERN.
CRAZY TALK -
These days, there is wild talk among some mathematical and research physicists---and especially proponents of “String Theory.” Lots of references to “multiverses,“ “other dimensions,“ “folded dimensions,” “alternate” and “alternative universes“---aspects of different realities we can’t see and probably will never be able to detect (except very indirectly) because they are extremely small and/or in “other“ or “hidden” dimensions. String Theorists speak of eleven or more “dimensions” as well as the usual four we know of. And there is even talk of “traveling back in time.”
PBS is once more advertising its three-hour series, “The Elegant Universe” with Brian Greene. It’s an excellent series, but frankly, I think it applies too much of subatomic, quantum “madness” and String Theory to our everyday existence. The thing is, we Humans can only perceive a narrow band of reality to begin with.
In our past, there was no clear survival value for Humans to be able to perceive the very nature of light itself, much less be aware of hidden dimensions. [Hallucinatory visions and things like hearing voices inside ones’ head are not necessarily gateways to anything other than the Human mind itself.] Perhaps there are creatures in other dimensions or in other Galaxies who evolved in ways even more strange than we, who can, by their very nature, comprehend or actually experience velocities on the order of the speed of light in their everyday lives. I think Star Trek has done an episode or two about such beings.
However, remarkable as they seem to us, our senses perceive only a small portion of the electromagnetic spectrum. Humans did not evolve to apprehend the velocity of things on the level of speeding photons---elementary particles which are the basic units of light and all other forms of electromagnetic radiation. [Nor was there any survival value to “seeing” things on the very small level of subatomic particles.] We see some portion of the light (electromagnetic) spectrum but the speeds at which electromagnetism travels is far beyond our capacity to readily imagine or visualize---which was Einstein‘s genius! The narrow spectrum of electromagnetic radiation we do see as light just seems instantaneous---but it does have a velocity---an enormous but theoretically finite velocity.
It takes a certain, rather miniscule amount of time for light sources on this Planet to reach our eyeballs. Further out, light coming from the sun takes about 8.5 minutes (a distance of 8.5 “light minutes“) to reach our eyes---but Humans didn‘t figure that one out until modern times. However, in the vast reaches of space, distances are measured in light-years---the number of years required for light to travel from a far distant source to our eyes, telescopes or detectors. This is one way cosmologists can see back into the past history of the Universe---the images captured by our deep space telescopes and the signals received by our radio telescopes are literally millions or even billions of light-years distant, and therefore, that old!
The light-year itself is actually a unit of measurement of distance. You can begin to appreciate how useful this measurement is to astronomers and cosmologists dealing with the immense size and distances of the Universe. Remember, light does generally travel more (?) or less at 671 million miles per hour---in the reaches of space those miles quickly add up to some very cumbersome numbers.
Back down to Earth. We have all noticed the difference between the speed of light and the speed of sound when we are located at a distance from the batter in a ball game. The batter is seen to hit the ball and then, a split-second later, the crack of the bat hitting the ball is heard. Same thing with lightning which is seen before the sound of the thunder it makes reaches our ears. Sound travels at a leisurely 768 miles per hour in dry air at 68 degrees F---or approximately one mile in five seconds. That’s how you can tell how far away lightning has struck---by counting the seconds between the flash and the thunder. When the thunder is almost simultaneous with the lightning it catches my attention!
The kicker to all this---and one of the cornerstones of Albert Einstein’s fame---is his now commonly accepted idea that nothing in the Universe can travel faster than the speed of light. That is, nothing (even an almost weightless particle) can travel faster than 186,282 miles per second---the apparent speed limit of the Universe. That’s according to Einstein’s famous special theory of relativity---which has been proven over and over by direct experiments and observations of very large things in space and very small things in particle accelerators.
INFINITIES AND AN INSTANT BLACK HOLE -
Basically, Einstein’s theory postulates that anything---even a teeny little particle with almost no weight---will become “infinitely” heavy if it exceeds the speed of light. Heavy stuff indeed! Here’s what “infinite” means. If we can just imagine the sudden appearance of an infinitely heavy object in a particle accelerator somewhere between Geneva and Italy---we can also visualize the entire Universe being sucked into it by the infinite gravity created by this infinitely heavy object that was once a neutrino.
The force of gravity also, by the way, travels at the speed of light, so we on Earth would get sucked right in by the infinite gravity of an infinitely heavy object, but a distant object such as the Sun would be sucked in 8.5 minutes later. And so on, until the entire Universe is vacuumed up into a great big Black Hole. Of course, that didn’t happen…
- Rudy Wittshirk
[Next: (Part Two) More Fun With The Speed Of Light---Science Shaking Up Science]