No Stupid Questions

If I’m not mistaken, their last paragraph describes this to contrast the answer above about the longest (I.e. lowest) frequency.

What the two other replies have neglected to mention as the cool side-effect of light affecting the curvature of spacetime despite being massless is that it's theoretically possible to make a black hole out of nothing but light. The concept is called a "Kugelblitz", https://en.wikipedia.org/wiki/Kugelblitz_%28astrophysics%29

The idea that a and very small wavelength would cause a black hole doesn’t really make sense to me since I thought a black hole requires mass.

It's mass OR energy.

Light, even though massless will still bend (and be affected by distorted) spacetime because it has energy in form of momentum. (See: gravitational lensing).

Mass and energy are basically the same thing though. Since E = mc² you can substitute mass in any equation with E / c².

Infinities are generally outside of practical applications, so you wouldn't. It's more of a thought experiment.

Couldn’t you keep stuffing more and more energy and get a bigger black hole?

I guess. But it wouldn't be light with a wave length anymore. It would be a black hole.

Also would such a blackhole move at the speed of light?

That's an interesting thought. I don't think so. Once you get the black hole it should gain mass. But that's really hitting the limit of my physics knowledge.

Nothing that has non-zero mass can move at the speed of light so no

Unless you specifically say "visible light" I assume "light" to just mean electromagnetic radiation.

https://en.wikipedia.org/wiki/Light

Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye.[1] Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz. The visible band sits adjacent to the infrared (with longer wavelengths and lower frequencies) and the ultraviolet (with shorter wavelengths and higher frequencies), called collectively optical radiation.[2][3]

In physics, the term "light" may refer more broadly to electromagnetic radiation of any wavelength, whether visible or not.[4][5] In this sense, gamma rays, X-rays, microwaves and radio waves are also light. The primary properties of light are intensity, propagation direction, frequency or wavelength spectrum, and polarization. Its speed in vacuum, 299792458 m/s, is one of the fundamental constants of nature.

I didn't know that some physicists choose such confusing terminology. Electromagnetic radiation is the more clear term and i have learned it as such in school, e.g. light being a part of the electromagnetic spectrum and generally speaking of electromagnetic radiation rather than light.