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Does anyone fear the sun might increase to a quasar? Is there any speculation there is a black hole somewhere?

Excuse my ignorance, I’m not knowledgeable about this stuff but it seems if the sun is becoming more active perhaps it could go as far as an explosion?

But I have faith in this forum for knowlegeable people in these areas. I’m constantly amazed at how much I learn here, so I thought I’d throw this out.

Not a chance. The sun is a variable star, so this means that the output of the sun will change by a small (for the sun) percentage. The sun is not massive enough to collapse into a black hole, only massive stars do that. These types of changes are perfectly normal for the sun, it has its 11 year cycle and 30-something year cycle (I think 36, but I am not too sure) that we have observed with sunspot activity over the past century, but there may be other, longer cycles that we just don’t know about, mainly because we haven’t been studying the sun for that long.

No, and nowhere near us, respectively.

We understand the steady state of stars quite well. Basically the fusion inside is supplying heat energy that counteracts very strong gravity pulling the upper layer of the star inward. The size of the star is set by the point where the two forces balance. It takes more energy release per unit time inside, to hold the surface layers of the star higher above the core. So, if the rate of energy production inside the star increases, it gets hotter, emits more light (though with a significant lag, as it takes energy a long time to fully work its way out to the surface), and then expands somewhat. Now occupying more area and radiating faster, its surface cools somewhat compared to what it was originally (it is also less dense etc). This all re-establishes an equilibrium again between the rate of energy production inside, and the light energy emitted, at which point the star stops increasing in size.

The size changes involved are modest unless the change in energy production in the core is quite dramatic. Late stage main sequence stars (like the sun, but best guess several billion years older) get substantially more energy inside from fusion of helium into carbon rather than hydrogen into helium - which can only start after the core compresses due to running out of hydrogen to fuse. That leads to a very large expansion into a red giant star.

But without changing over the fuel source from hydrogen fusion to helium fusion, the power output is only going to change by a few percent at most (say 10 as an upper bound), and that will always be compensated by a modest change in size, nothing like the huge expansion and diffusion involved in the transition to a red giant. Eventually the sun will expand to a red giant - but only after exhausting hydrogen in the core, probably a billion years from now.

Quasars, on the other hand, are thought to be active galactic nuclei - in other words, super massive black holes millions of times the mass of the sun, fed by rapid intake of surrounding matter, which a rotating black hole can convert into pure energy (light in all wavelengths mostly) with up 40% efficiency. They are associated with much younger galaxies than ours and only occur at galactic centers.