Alex McColgan

Think of electrons around an atom like fixed rungs on a ladder.

They can only exist at specific energy levels.

When a photon comes along, carrying just the right amount of energy to push an electron up a rung, that photon gets absorbed, and the electron gets excited.

Every element has a unique electron configuration.

so each element absorbs photons at unique wavelengths.

This is why spectroscopy works as such a precise fingerprinting tool.

For example, for hydrogen, 364.6 nanometers is the critical wavelength.

It corresponds to the exact energy required to liberate an electron from the second energy level completely.

Longer wavelengths are lower energy.

Shorter wavelengths are higher energy.

So, any photon with a wavelength shorter or equal to 364.6 nanometers has enough energy to ionize the hydrogen from that level and will be absorbed.

Any photon with a longer wavelength isn't energetic enough to bring about this change.

That's why the presence of a Balmer break tells you that there's hydrogen between a light source and your telescope.

Usually, a messy, complex object like a galaxy exhibits a smeared, gradual break because stars of different temperatures and densities are sending their light through gases of varying densities.

The sharper the break, the more pure the hydrogen atmosphere you're dealing with.

But a near vertical break, like the cliff, is twice as strong as that of any ancient cosmic body previously observed, which is why it's so intriguing.

The extreme properties of the cliff forced us to go back to the drawing board and come up with entirely new models, the graph admitted.

It seems this little red dot was sending mixed signals.

On one hand, spectra analysis appeared to suggest the object behind the cliff

was a supermassive black hole.