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What Happens When Light Goes Boom? Part 2: The Crowd, the Molasses, and the Speed of Light (Sort Of)

(This is Part 2 of a series on Cherenkov radiation — the “light boom.” Read Part 1 first.)

Before we get to Brad Bradington sprinting down the red carpet, we need to talk about the crowd itself. Because the crowd is where all the magic happens, and the crowd has some very specific properties that make this whole story possible.

Specifically: the crowd slows down light.

In 1865, James Clerk Maxwell published four equations that unified electricity, magnetism, and light into a single framework. It’s one of the towering achievements of 19th century physics — the kind of result that makes you feel like the universe was trying to tell us something, and Maxwell was just the person paying close enough attention to hear it.

One of the things those equations tell you, if you work through the mathematics, is the speed of light. It falls out of two constants — properties of empty space itself — and gives you exactly 299,792,458 meters per second. Not approximately. Exactly. The universe just decided that’s what light does in a vacuum, and Maxwell’s equations are how we know.

But here’s the asterisk: those constants describe the vacuum. Empty space. Put a material in the way, and those effective constants change. The material has its own electric and magnetic properties — its own way of responding to oscillating fields — and those properties act as a drag on the wave. The speed that falls out of the math is now lower.

How much lower depends entirely on the material. Physicists capture this with a single number called the index of refraction — the ratio of the vacuum speed of light to the actual speed in the medium. In air, the index is about 1.0003 — so close to vacuum you’d never notice the difference. In water it’s 1.33, meaning light moves at about 75% of its maximum speed. In glass it’s around 1.5. In diamond it’s 2.4, meaning light is cut to less than half its vacuum speed passing through the stone. HALF. We’ve even engineered special laboratory materials that slow light to walking pace — literally the speed of a person strolling down a corridor, achieved inside ultracold atomic clouds.

This is, if you stop to think about it, genuinely strange. Light doesn’t have mass. It can’t be grabbed or pushed. And yet the mere presence of atoms and molecules — the way they respond to oscillating electric fields, creating their own little ripples that interfere with the original wave — is enough to drag it down from the cosmic speed limit to something a fast cyclist could beat.

Now, WHY this happens in detail is a whole episode on its own. You can picture it a few different ways. You can imagine the light waves interacting with the electrons in each atom or molecule, which then generate their own little electromagnetic waves, which then interfere with the original — slowing the whole thing down like trying to run through a room full of people who all want to stop and chat. You can picture it as individual photons bouncing around in an elaborate quantum pinball machine. Or you can invoke something called phonons, which is my favorite picture because it’s both the most accurate and the most fun to say out loud.

But the HOW doesn’t matter for our story. What matters is the FACT: light inside a material moves slower than c. Sometimes much, much slower.

Here’s where it gets interesting.

In empty space, nothing can outrun light. Einstein’s special relativity closes that door completely, with no exceptions and no loopholes. There is no shortcut, no workaround, no fine print. The cosmic speed limit is absolute.

But what if you filled the stadium with molasses?

Usain Bolt runs at about 10 meters per second. In open air, light outruns him by a factor of thirty million. The gap is not closeable by any conventional means.

But if you fill the stadium with molasses, Bolt slows down. More importantly, light slows down too — and inside certain materials, light slows down dramatically more than a charged particle does. A fast-moving electron barely notices there’s a medium there — it plows through atoms like they’re not its problem. But light gets caught up in all those interactions, all those tiny delays, all that electromagnetic interference.

The result: inside certain materials, a sufficiently energetic charged particle can move faster than light is moving in that same material. Not faster than c — the vacuum speed of light, the true cosmic limit. That’s still inviolable. But faster than the local, in-this-material, slowed-down speed of light. Which is a very different, and entirely permissible, thing.

You’re not breaking any laws of physics. You’re not violating relativity. You’ve just found a material where light has to slog through molasses, and you happen to be a particle that barely notices the molasses is there.

And when that happens — when a charged particle exceeds the local speed of light in its medium?

Brad Bradington has entered the building.

In Part 3, we watch Brad Bradington sprint — and find out exactly what a light boom looks like.

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NASA Study Challenges Theories on Where the Ingredients for Life Came From

The question of how life began here on Earth, or how simple organisms emerged from chemical compounds, remains a bit of a mystery. While scientists have confirmed through fossil evidence and the geological record that life began roughly 4 billion years ago on the seafloor (around hydrothermal vents), it is still unclear how the ingredients for life came to Earth. The generally-held view is that they were brought here by comets and asteroids from the outer Solar System, which also delivered Earth’s surface water.

This theory states that planetesimals delivered these elements to the inner Solar System during the Late Heavy Bombardment, thought to have occurred between 4.1 and 3.8 billion years ago. However, a new NASA-supported study is providing new information about how primordial Earth acquired life-essential elements (LEEs). Their findings, published in the journal Science Advances, indicate that Jupiter likely played a key role in the process.

The research team hails from Rice University’s Department of Earth, Environmental and Planetary Sciences. As they indicate, the timing of the deliver of LEEs to Earth remains debated, as does the geochemistry of the planetesimals involved. Traditional models attribute it to outer Solar System chondrites, stony meteorites that formed two to four million years after the first solids formed in the Solar System. However, as the team noted, this accretion age rules them out as the earliest source of LEEs.

*Artist’s impression of a circumsolar debris disk, from which systems of planets form. Credit: NASA*

To break it down, all life on Earth requires the same basic elements, known by the acronym CHNOPS: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. These elements formed through the fusion of hydrogen and helium in the first generation of stars (Population III), which were then dispersed throughout the cosmos as clouds of gas and dust when these massive stars went supernova at the end of their short lifespans (tens of millions of years). These and other heavy elements (including silica, iron, and various metals) then coalesced to form subsequent generations of stars and planets.

Roughly 4.6 billion years ago, the Sun formed from a collection of this gas and dust (nebula), experiencing gravitational collapse at the center. The remaining material formed a disk around the new star, slowly accreting to form the Solar planets and planetesimals. What material remained, in the form of asteroids and comets, settled into different orbits, most into the Main Asteroid Belt and the Kuiper Belt. Others, meanwhile, fell into the orbits of planets – like Near-Earth Asteroids (NEAs) or Jupiter’s Trojan and Greek populations.

Over time, many of these objects have crossed Earth’s orbit, impacted the surface, and were recovered as meteorites. The study of these objects provides a window into the early Solar System, a much more chaotic time when Earth was still in formation. Meteorites fall into two categories, both of which originated from planetesimals that formed at different times in our system. These include dense metallic objects (iron meteorites) and stony chondrites, the latter of which constitute the majority of those found on Earth.

The oldest planetesimals are the source of iron meteorites, while chondrites originate from the second generation that formed 2-3 million years later. While some evidence points to chondrites from the outer Solar System delivering the ingredients for life late in Earth’s formation, scientists continue to debate which type of meteorites delivered Earth’s stock of LEEs. The new study suggests that things might have happened differently than traditional models suggest.

Using laboratory experiments and geochemical models, the team reconstructed a map of phosphorus-nitrogen (P/N) ratios across the early Solar System. Their results showed that during the first generation of planetesimals (iron), objects had a higher ratio of P/N in the outer Solar System, which decreased toward the inner Solar System. This trend was reversed in the second generation, where chondrites had higher P/N ratios in the inner Solar System.

*An illustration of our solar system. The asteroid belt lies between Mars and Jupiter, separating our system into the inner and outer regions. NASA/JPL-Caltech*

The team theorized that during the first generation, an outward flow of material raised the P/N ratio in the outer Solar System. This changed with the arrival of Jupiter, whose gravitational influence restricted the movement of phosphorus and nitrogen from the inner to outer Solar System. This meant that when the second generation of planetesimals appeared, those that orbited within the inner Solar System were left with a higher P/N ratio than their counterparts that orbited farther from the Sun.

These results suggest that, contrary to previous models, Earth acquired its phosphorus and nitrogen (both essential to life) primarily from the inner Solar System, without additional contributions from the outer Solar System. Their findings are reinforced by geochemical accretion models showing that Earth’s present-day P/N signature is best reproduced by inner Solar System planetesimals, regardless of whether they are related to iron or chondrite meteorites. As Rajdeep Dasgupta of Rice University, the senior author on the study, said in a NASA press release:

For our own solar system, Jupiter’s presence and growth history, indeed, seem to have played a critical role in determining the distribution of the basic chemical ingredients necessary for habitable worlds. It remains an open question whether a life-essential element budget similar to Earth’s can be established without a Jupiter-like planet in the population.

“The study suggests that Earth acquired its inventory of the life-essential elements phosphorus and nitrogen primarily from the inner solar system, without requiring a significant contribution from outer solar system chondrites,” added Pathak. As for the other LEEs, the means through which they were delivered to Earth billions of years ago remain to be seen and will be the subject of future research.

Further Reading: NASA, Science

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Fugitive wanted for 2 killings found in Laos after 8 years

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An 8-year-old manhunt for a suspect in two California killings came to an end this week after a South Korean national was detained abroad and returned to the United States to face murder charges.

Myung Jin Kim, 31, was wanted in connection with two killings, including a botched murder-for-hire plot in San Jose in 2016 and the killing of Kim’s friend in the parking lot of a CVS in Westminster two years later.

Prosecutors filed an arrest warrant for Kim in November 2018, but he is believed to have fled and eluded authorities for eight years.

Myung Jin Kim, 31, was taken into custody by Laotian authorities in late May.

“Mr. Kim’s cowardly acts of violence finally caught up with him, despite being halfway across the globe,” said Patrick Grandy, assistant director in charge of the FBI’s Los Angeles Field Office, in a statement.

Kim is believed to have hired a hitman for the ambush and killing of a man in San Jose on June 27, 2016.

Police say the victim was shot in his car after stopping by a residential neighborhood. But the investigation by San Jose police determined the hitman had killed the wrong person.

For years, however, no arrest warrant was issued for Kim.

Then on Sept. 5, 2018, Kim was suspected of shooting and killing his friend, 26-year-old Christopher Kim, in the parking lot of a CVS in Westminster after the two argued over money.

Authorities say Kim allegedly shot his friend six times in front of his girlfriend and then fled on foot.

On Nov. 20, 2018, police in Orange County issued an arrest warrant for Kim.

San Jose police continued their investigation into the 2016 killing as well and, on Feb. 3, 2020, an arrest warrant was issued for Kim for allegations of murder, attempted murder and conspiracy to commit murder in the botched murder-for-hire plot.

Kim eluded law enforcement for years until December 2025 when, according to a statement by the Orange County District Attorney’s Office, Westminster Police Department, FBI, San Jose Police and Santa Clara County District Attorney’s office, he was found living in Laos. Kim was taken into custody for alleged immigration violations, including using fraudulent travel documents.

Orange and Santa Clara county officials worked with the FBI and U.S. marshals to locate and bring Kim back to the states to face felony charges.

Kim was booked into Anaheim Police Department jail Tuesday, and he was transported to Santa Clara County on Wednesday.

Federal officials noted Kim was the first person detained and returned to the United States from Laos.