How slow can we make a beam or photon of light go?

Over 10 years ago a research team at Harvard slowed a beam of light down to 38 mph, (61 km/h).
Physicists Slow Speed of Light
I’m sure they’ve gone even slower since that time.

I heard once a scientist claim that light has never been measured at the exact same speed twice. Not only claiming it was a variable, but that the common speed we claim is actually an average. Not sure, but I think he also claimed that average was slowly getting faster.

Slowly getting faster?

@RealEyesRealizeRealLies The issue with variant speeds needs to keep in mind the speed of the planets rotation, revolution, and the movement of the solar system and the galaxy. That is a lot to calculate.

@LuckyGuy Researchers in Germany managed to stop light for a minute

“Back in 1999, scientists slowed light down to just 17 meters per second, and then two years later the same research group stopped light entirely — but only for a few fractions of a second. Earlier this year, the Georgia Institute of Technology stopped light for 16 seconds — and now, the University of Darmstadt has stopped light for a whole minute.”

Not only can scientists stop a beam of light, they can store information on it and send the info out on the beam of light when it is released.

Light itself is not slowed down at all. It is relayed though a sequence of absorptions-re emission cycles, but the light part of the wave still travels at speed c in between these events.

Oh pick me pick me!

@El_Cadejo Did they stop it, or just turn off the light?

This thread is becoming a conversation on the Speed of Dark….

Yet space isn’t a true vacuum.

The maximum speed for light is C (186,282 miles a second). As @El_Cadejo said, the velocity of light (one or more photons) was zero for as long as a minute under experimental conditions.

Put a lightbulb into a dark box.

Turn turn the bulb on for ten seconds.

Turn the bulb off.

Open the box and it’s still dark inside.

Where did the light go?

@RealEyesRealizeRealLies the bulb’s electromagnetic energies whose frequencies are visible to human vision are absorbed by the atoms in the box and radiated by these atoms as heat, non-visible electromagnetic energies with frequencies in the infrared.

@RealEyesRealizeRealLies The speed of light was calculated theoretically from Maxwell’s Equations in the late 19th century. The value isn’t disputed. Your physicist’s comment more likely relates the purity of an experimental vacuum – that is, a perfect vacuum is almost impossible to create, so the speed of light as tested will often be slightly slower than the theoretical figure.