The birth of Fluffy the photon

Sometimes all you need is a little push. For a tiny particle it can be the difference between life and not even being created at all. This story is about Bieber fans, Braveheart, the smell of barbecued meat, a glass wall and most importantly it’s a story about Fluffy the photon.

 

The tunnel is dark and quiet, with a smell of metal in the air. It’s supported by hundreds of evenly spaced pillars that are the core of the structure. Thousands of teenage girls are hanging out along the length of the tunnel, some of them just leaning against the pillars, others calmly walking around. But boy, they are looking glum. “A negative vibe”, their mothers would say. If one were to count them, they’d count exactly 74 teenagers for every pillar in the tunnel. A strange number, I admit, but let’s attribute that to the contractor that built the tunnel, Tungsten W. Wolfram; a man who generally weighs the positives and the negatives of such a structure quite well.

A switch flips. Along the length of the tunnel arrows flash and light up. “This way to Justin Bieber,” the arrows read. All hell breaks loose. For teenage girls, a message like that has some incredible potential. They burst out screaming and all start to run at the same time, suddenly amped up with energy. The current amount of girls moving through the tunnel is shockingly high, even dangerous. If it weren’t for a number of muscular bodyguards with large “R”s printed on their T-shirts offering some resistance against the flow, then ohm my god, things could go seriously wrong!

Despite the resistance of the bodyguards, things are warming up in the tunnel. More and more girls are starting to bump into one another, resulting in heated discussions. But the bodyguards know their jobs and don’t give them an inch.

And then, drama. One overexcited girl gets shoved hard, with a staggering amount of energy. Light flashes in front of her eyes … and there it is. Fluffy the photon is born!

At this point we have to slow down time a little bit, because Fluffy is FAST! Really, really fast. He’s in fact so fast that he’s having trouble seeing anything but a tiny dot right in center of his vision. Fluffy sighs. That’s what happens when you move at 300.000.000 meters per second and you’re the fastest kid on the block. Nothing coming from the back or side can ever catch up to you and things have to hit you right in the face to see them. Hmm, that didn’t sound like much fun, Fluffy thought. But then again, what did he know? He’d only popped into existence a trillionth of a second ago. In a manner of speaking, he could still hear the screaming in the tunnel where he had been born. In reality, that was total nonsense of course. Fluffy laughed as he soared past a couple of sound waves inching forward. He was in a completely different league now! Perhaps that was not so bad after all.

Just as he was getting comfortable moving at light speed, Fluffy hit the glass. He hadn’t seen it coming, but that was not a surprise given his limited vision. Even though he hit the glass at an angle, it still jostled him enough to refract his path and slow him down considerably.

This was annoying! It felt like he was wading through a swamp. Fluffy groaned. He really hoped this wasn’t going to go on for too long, because … Well, because what? he thought. It’s not like I have to be someplace. At least not that he could remember. But that didn’t come as a shock to the little photon, since he had only existed for one hundred billionth of a second.

He had just gotten used to his new speed, which at least widened the tiny circle of his vision a little, when Fluffy tumbled back into the clear, out of the glass. The sudden speedup surprised him, even putting him back on his original path.

Fluffy sniffed the air. What the hell? he wondered. Why do I smell barbecue? This was getting weird. But now was not the time for questions. He was back on track and nothing could stop him.

“Freeeeedoooom!” Fluffy squeaked. If he had known that not far away some other photons were shooting out of a TV screen playing Braveheart, he would have laughed at the coincidence. But Fluffy would never meet them. His trip would be lonely, and long. But what’s time to a photon anyway. It’s all relative, isn’t it? A positive attitude, that’s what’s important. Or at least a neutral one, in the case of a photon.

 

If Fluffy had been able to pick up at least some sound, then his reason for living would have been so much clearer. He would have heard Mrs. Edison say: “Oh come on Thomas, I know it’s getting dark, but please turn off the light bulb; you’ll attract mosquitos. Sit down and eat before the barbecue gets cold.”

For now, Fluffy the photon stayed in the dark about his existence. Figuratively speaking of course…

 

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What was this story all about? In one sentence: the creation of a photon in a light bulb by putting a current through the filament. Over half the sentences in this story contain a reference to a phenomenon in physics, so there’s a whole second layer to the story. Let’s have a look.

• The tunnel, with a smell of metal: The tunnel is an analogy for the metal filament of a light bulb, which is the curly wire strung between two metal rods.
• … supported by hundreds of evenly spaced pillars that are the core of the structure: The pillars represent the atom cores of the metal filament. In metals these atom cores are neatly lined up.
• Thousands of teenage girls, some leaning against the pillars, others calmly walking around: The teenage girls are the electrons circling the atom cores. Without a voltage on the metal, the electrons are in a low energy state.
• “A negative vibe”: Electrons are particles with a negative magnetic charge.
• … exactly 74 teenagers for every pillar. Attribute that to the contractor, Tungsten W. Wolfram, a man who weighs the positives and the negatives: Filaments in a light bulb are commonly made from the metal Wolfram with symbol W in the periodic table of elements, and is also known as Tungsten. Wolfram has periodic number 74, which means that it has 74 positively charged protons in its core and 74 negatively charged electrons circling that core.
• A switch flips: This one should be obvious 😉
• Arrows light up. A message like that has potential: When a light switch flips, it connects two points at a different potential. One point is at a higher potential than the other, indicating the direction in which charged particles move. You might know this potential as the voltage.
• … all start to run at the same time, amped up with energy: Once the voltage is established, electrons move from the point at low potential to the point at high potential, which creates a positive current in the opposite direction. Current is measured in Ampères.
• The current amount of girls moving is shockingly high, even dangerous: Unchecked, the current through a conducting material becomes dangerously high. It’s not high voltage that injures or even kills people being electrocuted, but high amounts of current. As an example, a taser used by the police is high voltage, but has a very low current going through the body.
• If it weren’t for muscular bodyguards with large “R”s printed on their T-shirts offering some resistance, then ohm my god: The bodyguards represent the resistance of the wire. Resistance reduces the current that can flow through a material by limiting the movement of the electrons. In science, resistance is written as symbol R and measured in the unit Ohm.
• … things are starting to warm up in the tunnel. Girls start to bump into one another, resulting in heated discussions: Movement of electrons and vibration of the particles in the metal wire results in generation of heat, warming up the filament.
• One overexcited girl gets shoved with a staggering amount of energy. Light flashes. Fluffy the photon is born: Electrons moving around an atom core have a preferred energy state at which they orbit (this is quite complicated, so I will not explain this in too much detail here). Think of it as the electron’s “comfort zone”. The electrical energy sometimes pushes an electron from the wolfram atoms to a higher, unpreferred energy state, causing the electron to be “out of its comfort zone”. This is called excitation. To get back to the lower energy state, it needs to lose the excess energy. The electron can do this by emitting (a.k.a. radiating) an energy particle called a photon. Photons are massless energy particles and are basically packages of energy.
• Fluffy is FAST: Photons move through a vacuum at the speed of light, which is quite fast. It’s worth noting here that the inside of a light bulb is not a vacuum, but filled with a gas to keep the wolfram filament from combusting.
• He’s so fast that he can’t see anything but a tiny dot right in the center of his vision: Photons have no eyes of course, but the point of this is a strange phenomenon in general relativity called the Relativistic Doppler effect. It’s too complex to explain in this article, but trust me, it’s a thing.
• … move at 300.000.000 meters per second: Light speed is approximately 300.000.000 meters per second. That seems like an incredibly big number and hard to imagine on a planet our size, but in the scale of the whole universe that’s really slow! For example, the light from our closest neighboring star, Proxima Centauri, takes 4.22 years to reach us.
• … fastest kid on the block: Nothing can move faster than light. The funny thing is, “nothing” actually CAN move faster than light. This would be one of the ways to achieve faster-than-light travel if we ever invent it; not moving faster than light, but compressing the nothingness in front of you. Did your brain just dribble out of your ears? Because mine did thinking about that!
• In a manner of speaking, he could still hear the screaming. In reality, that was nonsense. Fluffy soared past a couple of sound waves: The speed of sound is only a mere 343,2 meters per second, which is peanuts compared to the speed of light. When moving at the speed of light it would be impossible for our ears to pick up any sound that a voice produces.
• Fluffy hit the glass at an angle, refracting his path and slowing him down: The speed of light is 300.000.000 m/s in a vacuum, but in a different medium (like glass) the speed is less. At the border between one medium and another (for example between the gas inside the bulb and the glass bulb itself) the path of a photon is changed; a phenomenon called refraction. The changes to the angle and speed are material specific.
• Fluffy tumbled out of the glass. The sudden speedup surprised him, even putting him back on his original path: Since refraction works at both borders of the glass, and with opposite effects, the photon gets put back on track when it leaves the glass – I’ll note that the gasses inside and outside of the bulb are different, so the path and speed are not exactly the same, but it’s a close approximation.
• Some other photons were shooting out of a TV screen: Visible light from any source always exists of photons. It doesn’t matter if the light is generated by a light bulb, a TV, a red giant star or a white dwarf star; it’s always photons. Differences in color are caused by differences in the energy of the photon, more specifically its wavelength. Only a small range of wavelengths makes up visible light.
• What’s time to a photon anyway. It’s all relative: There are different laws to calculate time when something is moving near light speed, an oddity that is described in Einstein’s famous theory of special relativity. Time moves differently for something moving near light speed and an observer watching that movement. It’s all Lorentz transformations, reference points in spacetime and formulas. Just wave your hands mysteriously and say “and then I mathematics”, and people will just gape at you in awe – really, that’s how it works.
• A positive attitude, or at least a neutral one, in the case of a photon: Photons are particles without a magnetic charge. That’s called a neutral particle.
• Mrs. Edison: “Oh come on Thomas, turn off the light bulb.”: Thomas Edison was the inventor of the light bulb. His original designs used wood and paper as a filament, and after his patent was granted he and his team started using bamboo in their experiments.
• For now, Fluffy the photon stayed in the dark about his existence. Figuratively speaking of course…: This last one is a fairly self-explanatory wordplay joke, since Fluffy is a light particle.