OT: Dark energy might not be constant at all

"Dark energy" is the constant that Einstein had to introduce into his equations for the Universe to make a "Steady State Universe" model work.

The default solution to Einstein-Lemaitre was an exponentially expanding one which he didn't much like. He described it as his greatest mistake since reality was much more like his original equation solution as Hubble later proved by observation.

It is ironic that with improved observational data the same constant now seems to be making the universe fly apart at beyond exponential rate. I'm no great fan of "dark energy" but I am told by my friends still in the field that it is the least worst option now.

It means matter and radiation in the universe will eventually become very very thin indeed as spacetime rips apart ever more rapidly with time.

TBH I'd prefer there to be something wrong with the Type Ia supernovae standard candles in the early universe (making them overly bright).

I understand that possibility has been ruled out but I don't know any more details. They are very handy since when they go off they can outshine an entire galaxy and are visible over huge distances.

You can measure the light curve and determine absolute brightness from it provided that you catch it early. Amateur astronomers help the professionals by monitoring galaxies and reporting events in realtime.

Pro scopes only divert to look at them if there is something to see. (although there are some professional supernova systems as well)

The idea that the fundamental constants of nature might not be quite constant dates back to Dirac who was the first to make that conjecture.