PART 3

[The author would like to thank the geniuses behind the new Microsoft Paint for making the figures in this part possible.]

How are laser beams produced?

Laser beams are the product of stimulated emission of light. But what is stimulated emission of light? Before we can answer this question, we must first discuss how matter interacts with light.

Light absorption

Matter and light interact in two ways: matter can absorb light or it can emit light. When an atom absorbs a photon of light (a photon of light is a quantum of light energy), it takes the energy of that photon and one of its electrons become excited (although not sexually). An electron orbits the nucleus of an atom in one of the possible orbits. Larger orbits (orbits that take the electron farther from the atom) have greater energy. Normally, an electron will orbit the nucleus in the smallest possible orbit. This orbit is called the ground state. When an electron gets excited, it jumps from the ground state to an orbit with a higher energy. Such an orbit is called an “excited state”. An electron is excited when it is on one of the excited states. The excitation of an electron (represented by the symbol e^-) by a photon is illustrated by Figure 1 below.

Figure 1. A photon of light (red oval with wave inside) is absorbed by an atom, resulting in the excitation of one of its electrons (e-, gray dot).

The ground state and one excited state shown in Figure 1 are just two of the many possible orbits of an electron around the nucleus. From quantum mechanics we know that the possible orbits are quantized. The quantization of electron orbits is important, so let us stray a bit from the main topic to discuss it.

Using the most important equation of quantum mechanics, Schrodinger’s equation, physicist were able to discover that in a given atom, the electron can only have a certain set of energies. This set of energies is called the spectrum of the atom. The possible energies are denoted by E₀, E₁, E₂, E₃ and so on. E₀ is the smallest energy that an electron can possibly have. This is called the ground state energy. Obviously, this is the energy of an electron when it is in the ground state. (Recall that ground state is the smallest possible orbit.) E₁ is the energy of the first excited state, E₂ the energy of the second excited state, and so on. The energy of a higher excited state is always greater than the energy of the excited states before it. In other words, E₀ is less than E₁, which in turn is less than E₂, which again in turn is less than E₃ and so on. (E₀ < E₁ < E₂ < E₃ < …)  Now, here’s the most important bit. An electron in an atom cannot have energy between E₀ and E₁. It is simply impossible for an electron to have energy greater than E₀ but less than E₁. Also, an electron can never have energy between E₁ ­and E₂, or between E₂ and E₃, and so on. The set {E₀, E₁, E₂, E₃, …} gives the only possible energies of the electron.

Now we go back to absorption. Consider an electron initially in the ground state, so that its energy is initially E₀. Suppose then that a photon of light having energy E_photon hits the electron. This photon will be absorbed by the atom and its energy will then be added to the original energy of the electron. The new energy of the electron after absorbing the photon will therefore be:

E_new = E₀ + E_photon.

But take note of this very important fact: E_new must be one of the allowed energies of the electron. That is, E_new must be one of the following: E₁, E₂, E₃ and so on. This means that if the energy of the photon, E_photon­, is such that E_new is not one of the allowed energies of the electron, then the photon will be totally ignored – the atom will not absorb it. An atom will absorb a photon only if it will make E_new be one of the allowed energies of the electron.

Figure 2 below illustrates a particular example. The red photon is ignored by the electron because its energy is not enough to make the electron jump to the first energy level. The purple photon, however, was absorbed, because its energy is just right to make the electron jump from the ground state (where energy is E₀) to the first excited state (where energy is E₁). In other words, the sum of the red photon’s energy and the ground state energy (E_red + E₀) is not equal an allowed energy level, so electron ignores the photon completely. On the other hand, the sum of the energy of the purple photon and the ground state energy (E_purple + E₀) is exactly equal to E₁. Since E₁ is an allowed energy, the electron will absorb the purple photon.

Spontaneous Emission

The emission of light is just the inverse process of the absorption of light. Here, an electron in a certain energy level (that is, a certain excited state) falls down to a lower energy level (a lower excited state or the ground state). When an electron falls down to a lower energy level, we say that it “relaxes”.

Relaxation is just the inverse process of excitation. (Although this is only true for electrons. In humans, it’s certainly not the case.) When an electron relaxes, it loses energy. The energy lost is of course equal to the difference between the original energy and the new energy. This lost energy becomes the energy of an emitted photon. For example, consider an electron initially in the first excited state. This means that its initial energy is E₁. Suppose that this electron relaxes to the ground state, so that its final energy is E₀. It is not difficult to see that this electron lost energy, and that the lost energy amounts to E₁ – E₀. This energy becomes the energy of the emitted photon.

Figure 3. An atom spontaneously emits a photon of light. The energy of the photon is equal to the energy lost by the electron: E1 – E0

Of course, an electron does not have to come from the first excited state. It may come from the second excited state, or form the third excited state, and so on. The higher the electron falls, the greater the energy of the photon it emits.

The situation shown on Figure 3, however, is just one type of emission called spontaneous emission (which does not have to be nocturnal). This is called so because the atom spontaneously emits a photon of light. Most light sources we know produce light by spontaneous emission. In a fluorescent light bulb, for example, electricity is used to excite the electrons of the atoms of a gas (usually the gas is mercury vapor). But the excitations are only momentary, because the electrons spontaneously jump back to the ground state and in the process emit photons of light. (These photons of light, however, are not what we “see” when we look at a fluorescent lamp. The photons produced in the said process have wavelengths in the ultraviolet region. This means that they are invisible to the human eyes. These invisible ultraviolet photons, however, cause the phosphorescent compound coating the inner lining of the lamp to glow. The phosphorescent compound is the white powder that is found inside the bulb.)

Laser beams, however, are not produced by spontaneous emission of light but rather by stimulated emission of light, hence the phrase “stimulated emission of radiation”. The very suggestive and juicy term stimulated emission describes the phenomenon where an atom emits light due to the stimulation of another photon. Basically, stimulated emission is just like spontaneous emission, only that it is not spontaneous.

Why Stimulated Emission is Amazing

Stimulated emission has the following remarkable property: when a photon stimulates an atom to emit another photon of light, the emitted photon will have the same wavelength, phase, polarization and direction as the original photon. In short, the emitted photon is just a Doppelganger of the photon that stimulated its emission!

Figure 4. A photon stimulates an atom with an electron in the excited state to release another photon. The emitted photon has the same wavelength, phase, polarization and direction as the original. One can think of it s a “clone” of the original.

We can now see that when one has enough atoms with electrons in the excited states, then one can use stimulated emission to greatly increase the intensity of a certain light. This is because light intensity can also be measured through the number of photons in a given beam. The more photons there are, the greater the intensity. But notice that stimulated emission has the ability to practically double the number of photons of the given light source. This is illustrated in Figure 5 below, where three atoms with excited electrons are used to double the number of photons from three to six. This is where the “light amplification” part of LASER comes from. (Recall that laser means “light amplification via stimulated emission of radiation”.)

Figure 5. There are initially three excited atoms and three photons. Due to stimulated emission of radiation, the number of photons has been doubled from three to six. After emission, the electrons of the atoms are already in the ground state.

But the light is not merely amplified by stimulated emission. The beam produced due to stimulated emission has the remarkable property of being composed to photons with the same wavelength (and therefore color), phase, polarization and direction. This is the reason why laser beams are highly monochromatic and coherent. Remember that to be monochromatic means to be composed of only one color. Since a laser is practically composed of an army of photon clones, a laser beam is very monochromatic indeed. Also, since the emitted photons have the same phase (which can be thought of as the tempo or vibration rhythm of the photon), polarization and direction, a laser beam has very high spatial and temporal coherence. In short, all the remarkable properties of laser beams are derived from a very remarkable property of stimulated emission!

Laser Devices

But now I hear the result-oriented and practically-minded among you say: “But how do we prepare a collection of atoms with excited electrons? Does this not mean that we also need photons to excite these electrons? And does this not mean that we are cancelling the amplifying effect of stimulated emission because we will be using photons to double the number of photons? Isn’t it like investing 500 pesos to gain 500 pesos?” Well, the answer is that light absorption is not the only way to excite electrons. There are many other ways to cause electrons to become excited, like hitting them with electricity or heating to very high temperatures them. There are many different kinds of lasers and each kind uses a different strategy to prepare atoms with excited electrons. But once such atoms are prepared, stimulated emission can then be exploited to double the number of photons from a certain light source, thereby increasing the intensity of the light.

In fact, in laser devices, the number of photons is not merely doubled, but is increased by several orders of magnitude. This is done by placing the gain medium in an optical resonator, as shown in Figure 6 below. The gain medium is the material that is used to amplify light. An optical resonator is a combination of two mirrors that make light bounce back and forth between them. One of these mirrors is a totally reflective mirror, while the other is a partially reflective and mirror. The partially reflective mirror allows some of the laser beam to pass while it reflects the rest. The beam that is reflected back can again stimulate even more atoms with excited electrons to emit photons. When it reaches the other end, it will be reflected by the totally reflecting mirror, and will then pass through the gain medium again, before reaching the partially reflecting mirror, where the cycle begins again. Notice, however, that once an atom is stimulated to emit radiation, its electron has already relaxed to the ground state. This means that after several rounds of stimulated emission, all the atoms will have ground state electrons only. So that the production of the beam is continuous, a “pumping energy” must be supplied to the gain medium constantly so that the atoms of the gain medium always have excited electrons.

Figure 6. A simple schematic of a generic laser device.

Summary

Now let us sum up all that we have discussed in this series. We started this series with a question: What in the world is laser? Well, laser is short for Light Amplification via Stimulated Emission of Radiation. A laser device is a device that produces laser beams via a phenomenon known as stimulated emission. Because of the remarkable properties of stimulated emission, laser beams have the extraordinary property of being monochromatic and coherent. By saying that it is monochromatic, we mean that it only has one wavelength. By saying that it is coherent, we are saying that its photons are oscillating or vibrating “to the same rhythm and beat”.

Now I hear the astute ones among you say, “Wait a minute, I see an inconsistency here. One minute you describe light as being made up of waves; electromagnetic waves, to be precise. But now you are describing them using particle-like entities called photons. What really is light made of, electromagnetic waves or photons?” This is a very good question, and it has a very remarkable answer: Light is made both of electromagnetic waves and photons. But how is that possible?

Now that is a topic for a separate series.

PART 2

What do we mean by “highly coherent, usually monochromatic beam of electromagnetic waves”?

For the sake of brevity, from now on we will use the word ‘light’ to denote not only visible light (electromagnetic waves our eyes can see) but electromagnetic waves in general. That is, when we say ‘light’ we mean electromagnetic waves, including radio waves, gamma rays and ultraviolet.

Now, a monochromatic ray of light is one in which the waves have the same wavelength or frequency. (The word ‘monochromatic’ came from the Greek words mono, meaning one, and chromos, meaning color.) A ray of white light is not monochromatic since it consists of waves of different wavelengths. In other words, white light is made up of light of different colors. On the other hand, the light emitted by a colored light emitting diode (LED) is usually monochromatic. A blue LED emits only blue light.

The fact that laser beams are highly monochromatic finds use in many scientific and engineering applications, such as spectroscopy. In spectroscopy, laser beams with a very specific wavelength are sent through a sample to be analyzed.

The next important property of laser beams is their high coherence. (What is certain is that they more coherent than the CBCP or the Vatican.) In the language of wave physics, coherence is the property of having waves that oscillate in phase of each other. Coherence comes in two kinds, temporal coherence (coherence in time) and spatial coherence (coherence in space).

Temporal coherence (coherence in time) would be best explained by an analogy in dance: for two dancers to be able dance the tango well, their stepping must have the same tempo. In other words, dancers performing a ballroom dance must have temporally coherent foot movements.

Temporal coherence is very closely related to monochromaticity. In fact, temporal coherence is used to measure monochromaticity. Another important aspect of temporal coherence is uniform polarization. This gives laser beams their characteristic ‘glare’, which makes them dangerous to the eyes. Sometimes, the glare of laser beams is used by the police or the military to disorient a pursued individual or an enemy.

Spatial coherence, on the other hand, means that a ray of laser light can be focused to a very narrow beam, often called a “pencil beam”. In other words, laser light can be focused to a very small spot. This makes laser beams ideal for applications that require great precision, like reading digital information encoded in a CD, cutting intricate patterns into metal or wood, burning away tumors without destroying neighboring healthy cells, or correcting vision problems without further damaging the patient’s eyesight. In microscopy, lasers are used to obtain blur-free images of very small objects at various depths, and this is possible because laser beams can be very narrow. And do not forget the use of lasers in increasing the chance of a headshot.

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Figure 1. An illustration of coherence and monochromaticity. [Image copyright by knowledgerush.com

Spatial coherence is also the reason why lasers have high intensity. To understand why, it is important to know what intensity is in physics. Intensity is defined as the power distributed over a given area. In equation form,

Here, power is the energy delivered by a source of light per second. The more energy a source is releasing in a second, the more power it delivers. Power is measured in watts (W). We are all familiar with the fact that different household appliances have different “power ratings”. The higher the power rating of an appliance, the more energy it delivers per second. In the case of light bulbs, a light bulb with greater power rating delivers more light energy per second than another light bulb with a lower power rating. For example, the light energy released per second by 20-W light bulb is two times more than the light energy released by a 10-W light bulb.

But notice that intensity is power over area. If power is distributed over a large area, then the intensity will be low. For this reason, the intensity of light from a normal light bulb dies down quickly as one go away from the source. In a normal light source, light energy is distributed over an area that becomes larger as one goes farther from the source. On the other hand, because of the spatial coherence of light emitted by lasers, the light energy they emit is concentrated in a very small area. This results in a very high intensity beam. The difference between a normal light bulb and a laser is illustrated by Figure 2 below. Figure 2a depicts the light emitted by a normal light source (like the light bulbs used at home). Figure 2b depicts the light emitted by a laser.

Because laser beams are composed of light rays that are concentrated in a very tiny area, they have very great intensity. Any Star Wars fan knows this; in the hands of an evil Empire, the high intensity of lasers can be used to wipe out whole races and destroy entire planets in a single colorful display of lights (all while orchestra music plays in the background, of course).

Back to the real world, the great intensity of laser beams finds countless industrial applications such as in laser cutting, laser wielding, laser brazing, laser melting and laser bending.

As with almost all technologies, the limits of laser technology depend only in the imagination of the engineer. In the hands of a very creating engineer (hopefully not an engineer of the Empire), the applications of lasers is limitless. Other current laser applications are laser ranging (using lasers to measure great distances), pollution monitoring, therapeutic skin treatments, holography, and nuclear fusion (where lasers are used to compress a nuclear fuel tight enough to cause a fusion).

And can you still imagine using a ball mouse? I can’t. So in summary: lasers rule!

We are now ready to address the last question: how are such beams of electromagnetic radiation produced in the first place? In the last part of this series we will see how.

Figure 3. A test sample bursts into flames as a laser beam (here invisible to the naked eye) hits it.

PART 3: How are laser beams produced?

References:

[1] Hitz, Ewing and Hecht, Introduction to Laser Technology, 3^rd ed. IEEE Press, 1998.

[2] Griffiths, Introduction to Electrodynamics. Prentice-Hall, 1999.

[3] Harris, Nonclassical Physics. Addison-Wesley, 1999.

[4] www.knowledgerush.com

What in the world is laser?

PART 1

[Disclaimer: The author does not own Figures 1-4, nor does he own Yoda, although he certainly wishes that he does.]

We use them to point at things in a slide presentation; snipers use them to point at heads ready to be shot. They make cool technologies possible, from CDs and grocery store barcode scanners to metal cutters. We often hear that they can cause blindness, but we also know that they are used in surgical methods to correct many vision problems. In science fiction movies they shoot out of space ships, one can engage in duels using swords made of them, and there are ships which can destroy entire planets using them. Laser beams — they are both boon and bane. But what in the world are they?

Laser, what in the world is, hmmm?

What in the world is laser?

The word laser stands for Light Amplification through the Stimulated Emission of Radiation. Originally, ‘laser’ is a term for the light emission mechanism that produces a beam of laser light (a laser beam).  Today, however, ‘laser’ is used to denote devices that use the said mechanism to amplify light via stimulated emission of radiation.

Now, a laser beam is a beam of highly coherent, often monochromatic electromagnetic waves. Laser beams are produced when stimulation emission of electromagnetic waves amplifies light. If you think that these are quite a mouthful, then grieve not, for in this series we will explain what they mean.

But what is an electromagnetic wave?

An electromagnetic wave is an oscillation or vibration in the electromagnetic field in a certain region of space. All the colors of the rainbow our eyes can see are electromagnetic waves of different wavelengths. Among the colors of the rainbow, red has the longest wavelength while violet has the shortest. All the other colors have wavelengths between that of red and violet. The closer to red a color is the longer its wavelength, while the closer a color is to violet the shorter its wavelength. White light is the result of the combination of all the colors of the rainbow.

But the colors of the rainbow (or of the LGTB flag) comprise only a sliver of a segment in the electromagnetic spectrum. The electromagnetic spectrum is the continuum of all possible wavelengths (or frequencies) of electromagnetic waves, and the segment of the electromagnetic spectrum comprising the wavelengths visible to our eyes is called the visible light region. Other kinds of electromagnetic waves are invisible to our eyes, such as infrared rays, which have wavelengths longer than those of red light, and ultraviolet rays, which have wavelengths shorter than those of violet light. Radio waves, the kinds of electromagnetic waves we use to transmit radio signals, have wavelengths even longer than those of infrared light. X-rays and gamma rays, on the other hand, have wavelengths shorter than those of ultraviolet rays. (We can also describe electromagnetic waves using their frequency. Frequency is the inverse of wavelength, so that as wavelength becomes longer frequency decreases, and as frequency increases wavelength becomes shorter.)

Figure 1. The electromagnetic spectrum.

But what is an electromagnetic field?

Let us start with electric fields and magnetic fields. An electric field is a force field created by a charged particle (such as an electron or an ion) or by an object with an excess of charged particles. A magnetic field, on the other hand, is a force field created by a piece of magnetic material (such as a bar magnet) or by a steady electric current. The electric field is a vector field specifying the electric force that will be experienced by a particle of unit charge if it were located at a specified point in space, while the magnetic field is a vector field specifying the magnetic force that will be experienced by a unit current if it were located at a specified point in space.

In the early 19^th century, Michel Faraday (an English chap who had nothing better to do but study current-carrying wires and magnets) discovered that a changing magnetic field also creates an electric field. Then in the latter part of the same century, James Clerk Maxwell (another English chap who had nothing better to do than to make mathematical models out of other scientists’ observations) discovered that if the law of the conservation of charges is to be valid, then a changing electric field must also create a magnetic field. This latter discovery by Maxwell led to the famous Maxwell’s equations. It is hard to overstate the importance of Maxwell’s equations. The four equations of Maxwell are among the most important, if not the most important equations of physics.

One profound implication of Maxwell’s equations is that electricity and magnetism turn out to be two facets of the same phenomenon; this phenomenon is known electromagnetism. Because of Maxwell’s discovery, we know that an electric field and a magnetic field are just different manifestations of the same field, the electromagnetic field.

Another equally profound implication of Maxwell’s equations is that visible light is an electromagnetic wave. In short, light is just a vibration in the electromagnetic field in a certain region in space! This realization led to the discovery that there are a host of other electromagnetic waves, all of them invisible to the human eyes. As mentioned, the radio waves we use to transmit radio signals and the X-rays we use in medicine are, like the LGTB flag, just dancing electromagnetic fields.

Figure 2. The electromagnetic field lines (blue) near a pair of charged particles. The red lines represent points with the same electric potential.

Figure 3. Iron filings lining up near a bar magnet. The pattern of the iron filings reveals the pattern of the invisible magnetic field lines.

Figure 4. Light waves as electromagnetic waves. The oscillations in the magnetic field and in the electric field are shown.

To be continued.

Part 2: What do we mean by “highly coherent, usually monochromatic beam of electromagnetic waves”?

Part 3: How are laser beams produced?

[1] Hitz, Ewing and Hecht, Introduction to Laser Technology, 3^rd ed. IEEE Press, 1998.

[2] Griffiths, Introduction to Electrodynamics. Prentice-Hall, 1999.

[3] Harris, Nonclassical Physics. Addison-Wesley, 1999.

[4] Ask a Mathematician/Ask a Physicist, http://www.askamathematician.com

[5] Coherence, http://electron9.phys.utk.edu/optics421/modules/m5/Coherence.htm

Warning: For those who haven’t seen this episode yet, spoiler alert!

This is the first, and hopefully won’t be the last, of a series of short reviews I’ll try doing each week for ‘The Big Bang Theory’.

This week The Big Bang Theory (TBBT) episode ‘The Einstein Approximation’ came out,  and is the 14th episode of the show’s 3rd season.
Let me just start this quick and short review of the episode by further stating what the guys there and I have in common, apart from the quite obvious facts that we’re all geeks/nerds by heart.
Even before TBBT, I’ve admired and idolized Einstein myself, because of his great mental feats (which were of course, backed up by other physical theories and experiments at his time). Great because by just the power of his mind Einstein was able to revolutionize our lives and the 20th century, paving ways for faster transportation, not to mention telecommunication and computing, which drove and is still driving the information revolution today. And of course, so much more benefits which we more or less take for granted in our daily lives. In fact, Einstein is oftentimes synonymous with the word ‘genius’.
Einstein was also very much interested in philosophy and politics, not just physics. He’s written several books, articles, letters to people outside the scientific community. He also has a quirky sense of humor, as seen from this  picture of him. At first I thought this photo of Einstein was edited. But as it turns out it was really him, tongue hanging out and all.  It was at the time he was making fun of people taking pictures of him. Great stuff.

Of course Einstein is not without criticisms. Great and accomplished a scientist he maybe, history tells us he left much to be desired when it came to being a father or a husband.

Now, back to the episode review of TBBT. At this point I shall establish a partially objective, partially subjective point system of each episode relative to the earlier 2 seasons (which I have watched at least 2 times…) and a number of judging criteria.

This episode is a classic Sheldon episode, which is great in itself. Again we expected lots of ‘weird’ humor: Sheldon’s ability to complicate relatively simple things, as well as him belittling his friends, most noticeably Penny. Hilarious stuff once again. Bravo to TBBT production team.
Not a lot of scifi or comic book references were made though. But lines such as:

Howard: How long has he been stuck? (referring to Sheldon)
Leonard: Umm…intellectually about 30 hours, emotionally about 29 years.

And

Howard: Have you tried rebooting him? (referring to Sheldon)
Leonard: No I think it’s a firmware problem.

Are classics. 

The part where Leonard and Sheldon were arguing inside the ‘ball play room’, with Sheldon going ‘bazinga’ everytime, was also hilarious.

Sheldon, and of course the rest of ‘the guys’ are fans of Einstein no doubt. Sheldon of course thinks he’s at the same level with Einstein so he tries to do what Einstein did in order to come at the epiphany that is the special theory of relativity: to work for a menial job so he can occupy his basal ganglia with a routine task so he can apparently free his pre-frontal cortex to solve his physics problem.

Another classic moment in this episode is the guest starring of Yeardley Smith, the not so well known voice actor behind the famous cartoon character Lisa Simpson (yes, of ‘The Simpsons’ fame). Absolutely entertaining piece of the episode.

Another classic dialog is again with Sheldon and Penny:

Penny: What are you doing here?
Sheldon: A reasonable question. I asked myself, what is the most mind-numbing, pedestrian job conceivable? And 3 answers came to mind: toll booth attendant, an Apple Store “Genius”, and “What Penny does”. Now, since I don’t like touching other people’s coins, and I refuse to contribute to the devaluation of the word “genius”, here I am (meaning at the cheesecake factory).

Lines like these make me think of the real meaning and application of LOL. 

I suppose myself and those guys, as well as the show’s production team, can’t help cracking jokes at Apple. 

Overall I’d give this episode the following scores:

* reference to sci-fi, comic books, and other geek/nerd pop culture: 6/10

* reference to physics and other fields of science: 9/10

* dialog humor factor: 9/10

* techie/technology factor: 8/10

which gives an overall score of: 8/10

Article originally published here.

The premise: a problem

It has been said over and over again, as a defense or even as a backlash, by religious men and women that religion has a curative and comforting utility to humankind like no other. It has also been said over and over again by secular people and rationalists that however comforting some belief or idea is, it nevertheless adds nothing to the truth value of the belief or idea. That secularism offers nothing more than a skinny comfort blanket amidst the cold and pouring rain at best. That may well be true, and indeed it leads me to believe that it all boils down to what we really want: happiness or the truth. Happiness may not necessarily be true or what’s really happening, and having the truth may not necessarily make one happy. This conflict reminds me of the doggedly proverbial “The truth hurts” and The X-Files’ “The truth is out there”. This conflict also reminds me of the struggle in the movie The Matrix, wherein to know the truth, one has to be ‘removed’ from the confines of the complacency brought about by the virtual reality of the machines who have taken over. Once one has learned the truth, which involves living as a fugitive or freedom fighter wearing mostly ragged clothing near the center of the Earth, one is left to wonder if it would have been better to have stayed in the fantasy reality, even though it’s all make-believe. I guess it wouldn’t be so surprising considering the fact that human beings, like almost every other animal, are predisposed to follow what is certain to help in the continuation of its species. After all, speaking in ageological time scale, homo sapiens are but cells that have just fertilized, and are beginning to undergo cell division to form a larger animal.

The question

So then, if you will humor my ponderings, what could secularism possibly offer as an answer to one of the most profound questions we humans have asked since the dawn of our consciousness: What is death or what happens when we die? Do we survive death in some form or is there nothing after it?

Setting the mood

Quite a mouthful of questions, and ones that have plagued thinkers or philosophers for centuries upon centuries. But I think before I even begin to give my answer to those questions, a little ‘mood setter’ is in need. Some questions are too frank or too blunt in manner, which sometimes has the effect on the listener or the questioner of making one lose focus on the more relevant and apparent details. The mood setting quote is from the book Unweaving The Rainbow by prof.Richard Dawkins. It’s his reply to people who keep on ranting or complaining or fussing about their deaths. Everytime I read it, especially when I watched and heard prof. Dawkins read it with emotions in a talk at UC Berkeley, I cannot help but be moved by it’s message, wrapped around in romantic scientific prose:

We are going to die, and that makes us the lucky ones. Most people are never going to die because they are never going to be born. The potential people who could have been here in my place but who will in fact never see the light of day outnumber the sand grains of Arabia. Certainly those unborn ghosts include greater poets than Keats, scientists greater than Newton. We know this because the set of possible people allowed by our DNA so massively exceeds the set of actual people. In the teeth of these stupefying odds it is you and I, in our ordinariness, that are here.

And continuing this passage in his talk:

We privileged few, who won the lottery of birth against all odds, how dare we whine at our inevitable return to that prior state, from which the vast majority have never stirred.

Makes one (or at least myself) wonder if we even have the right to feel anger or guilt or even sadness by our undeniable demise.

Physics on death

An episode of The X-Files has agent Mulder talking to agent Scully about starlight. He says that starlight as we see it here on Earth is already billions of years old, and has traveled unimaginable distances (light-years). Stars that are now long dead, but whose light is still traveling through time. Mulder continues that perhaps that’s where souls (our souls, after we die) reside. Today, we know from physicists that the premise is correct (that starlight is very old and still keeps on traveling), but we can’t be certain (or perhaps not at all) about the succeeding statement of Mulder (about souls). Scully, Mulder’s partner, continues Mulder’s statements by saying that the light doesn’t die, and that maybe that’s the only thing that never does. Speaking in a purely Einsteinian fashion when dealing with spirituality and such, perhaps our ’souls’ do reside in starlight, and in that sense our ’souls’ do continue on forever.

Mulder’s statement

Taking the first statement into consideration, that ’souls’ do reside in starlight, to be technical about it, we can probably say that it’s actually not starlight in our case but ‘planetlight’. We know that in order to see an object we have to shine light on it, after which the light bounces back, illuminating the object, back to our eyes. In the same sense, the Sun illuminates Earth at daytime, and at nighttime the Moon or our electrical/electronic devices light us up and our surroundings. In that sense light is shined on us, and so it is reflected back, which eventually reaches outer space and into the vast cosmos. In this way our ’souls’ which in this case means our whole lifetime under some source of light, is ‘framed’ in a ‘wave’ of light cruising the universe. If there are intelligent lifeforms out there in the universe and they can’t come here due to technological constraints (same as our case), once they try viewing our part of the universe, what they’ll be seeing is planetlight (which is reflected starlight, the star being our Sun or light from some other source) containing us, our lifetimes, and our history. What they’ll be seeing of course depends on many factors such as how far they are from us, how sensitive their viewing instruments are, what time they tried viewing us, among other things.

Scully’s statement

As for Scully’s statement, that starlight doesn’t die, technically speaking that can be true, since as long as photons don’t get smashed or absorbed, they keep on travelling in space, most likely till the edge of the universe and (our) time itself. However there is a limit to how long light can travel for one to be able to ‘reconstruct’ the data (in this case our ’souls’) it carries with it. This is because as light travels, similar to a wave, it spreads across time and space. As the light spreads, at some point in the universe very distant from the light source, it will be nearly to absolutely impossible to know what information that light brought with it. In a word, the light will be too ’stretched’ to make any sense out of it. This is similar to research being done on the Big bang. We are in an epoch of the universe where we can still study ‘cosmic background radiation’ (electromagnetic radiation, same as light) leading back to the Big bang. If we were a few millions of years late, we might not be able to analyze the data that comes along with the cosmic background radiation. And so Scully is partially correct since light can possibly not die, but the information in the light may become lost to us or someone viewing us.

Finally, physics on immortality

In essence, our ’souls’, most of our memories, achievements, feats, and other things in our light-stricken lives continue to propagate into inter-stellar space. The propagation duration many orders of magnitude longer than any of our lifetimes combined, which could be treated as practically infinity, and in some ways, immortality.

Originally posted last September 16, 2008 at f241vc15.wordpress.com.

Nope that’s not a typo and this isn’t technically about religion or another reconversion post.  This post is about holes in space, namely black holes, wormholes, and the lesser known white holes, and their implications to the physical and metaphysical. The arrangement or flow of exposition of this article, from black to worm to white hole, will become much clearer as you read along the article. So get ready for a layman’s quick rundown on holes (cosmic ones of course), thought experiments, sci-fi love, paradoxes, and various possible implications in our lives and the universe we live in.

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