Most supernovae are misclassified as nebulae...

...Because the calculations reflecting the speed of light en route to Earth are off, since they don't take into account the effects caused by the confluence of time dilation and dark matter across the long trip that the photons take.

The title refers to numerous photos of nebulae, which I think are really supernovas in progress. I attribute this misclassification the the sheer distance involved and what I think are inaccurate speed-of-light calculations, because the distance between an event and Earth is so great. So, even a quick event in a galaxy far, far away just appears to happen very, very slowly when viewed from here. — So slowly for that matter, that the event looks to be in a standstill.

Dark matter, black holes, and other crazy theories

What I think dark matter is

Dark matter, in turn, is gravity from black holes (aka singularities) not (yet) manifest in this realm. These black holes are singularities, but not black holes, because they haven't opened up yet, but are close enough to the 'wall' separating them and this universe to cause gravimetric emissions. Alternately, I can describe dark matter as just a gravimetric echo of a black hole not yet manifest.

Imagine putting small magnet pieces on paper and then moving them around using a big magnet on the other side of that sheet of paper. The sheet of paper is that wall.

The black holes themselves don't open up just like that. A typical process in the lifetime of a manifest black hole is first to collect enough matter. And well, if there's no matter, then the singularity won't bother either.

But — if there's enough matter, the gravity of the non-manifest black hole (the 'dark matter') will collect the matter together. The right elements that are easier to attract will congregate into one or more masses, of which one such mass is large enough to be solar-forming.

The catch is, that black holes rotate, and the solar material basically chafes at the fabric of the 'wall' separating ths realm from what is probably another one. One possibility is, that a certain small amount of solar material moves from this realm through an inner back hole (inside a sun) to the other side. Well, enter pulsars. Some pulsars are long-lasting and stable, but emit solar material from the other side transmogrified into very powerful pulsar emissions.

Now, the stars and the suns are just pimples of the universe, which are mostly stable. In some cases, a star runs out of fuel (collected matter) and becomes a dwarf.

In other cases, there is some kind of an imbalance that causes a supernova to happen.

An open black hole sucks everything in; imagine a drain, and water going through it is just space. But in space, it's totally 3-dimensional. |There might be more dimensions.|

For a supernova, one option is, that as the amount of solar material increases, a black hole within the stellar object gets more powerful (and maybe sucks more in). Or that it is sustained, along with the star around it. Once the stellar object runs out of fuel, the opening of the singularity inner to the stellar object cannot be sustained, and as that singularity leaves its 'nest' and closes within the stellar object, the remaining solar material that has so far made up that stellar object — unable to be to be sucked in anywhere — disperses. Often violently.

Imagine a rubber balloon and then applying pressure from its hind end. Apply too much pressure, and the ballooon pops. The rubber pieces of the balloon fly around quickly and sometimes violently, as they hit stuff in their way.

13.11.2016 update.

I later thought about actual open black holes that don't have any light around them. As I'd described stars as pimples of the universe, then I could think of not just one type of supernova, but more than one.

So, one type of supernova is likely to be caused by dispersing solar (and other) matter once a singularity has closed up, but the collected matter around the closing doesn't have anywhere to move. That's described above. To add to that, such a nova happens, if the closing is not safe, or if there's surplus material and gravity, and maybe an imbalance involved, but the hole itself closes.

The other type of supernova is caused by a tear in the continuum. The magnets and paper description might come into play here, as rotating black holes are covered by stars (note, that manifest singularities are circular, but instead of forming a mass, they are 3D drains when open), which avoid, prevent or delay the tear from happening.

So it could be, that a certain star runs out of fuel, but a greater imbalance causes the black hole to manifest.
What may be causes to the imbalance, are unknown. Perhaps lack of sufficent matter to close the hole, if the singularity is too powerful. In that case, it's not so much solar matter exploding outwards, but a violent opening, whereby normal gravity is pushed away, in the process also pushing outwards, but not destroying/extinguishing all extant matter that is in the way. That is disperesed before the hole opens.

At this point, I'm too tired, and the previous paragraph is too illogical even to me. I'd rather read up on Wikipedia about actual discoveries and proofs, but later.

All this from the crazy theories dept. I felt so giddy this hour, that I wanted to put out something off the wall with lots of non-sensical technobabble.

Added minor wording and idea updates a few days later.