However, since you said ‘about the universe’ and not about physics, I would be tempted to look at mathematical side too. Math is supposedly axiomatic, so there is nothing more surprising than discovering something completely shocking and unbelievable and horrendous in a system of thought you put down *yourself*. And of course Godel sits near the top in that realm. Logic itself is inconsistent, i.e, illogical, or incomplete. Which is possibly harder to swallow. That discovery goes beyond surprise IMHO. It goes against not just what we thought but how we thought (and continue to think). We’re still doing science logically, using notions of causation and such, even though it is potentially a dead end. We have no other options, unless I am mistaken. That’s pretty damn surprising and downright scary to anyone new to science.

Future surprises: let someone link the coupling of information and thermodynamics with either QM or fundamental mathematical logic, or both. I think I’d be spilling beers over that for a very long time . And speaking of time.. never mind

Now, most surprising things that might turn out to be true? My list is, ahem, unsurprising:

1. That consciousness isn’t necessarily tied to our physical brains and can be transferred and preserved to facilitate immortality.

2. That intelligent life on earth is unique in the universe.

3. That intelligent life on earth isn’t unique in the universe and its evidence turns out to be nearly ubiquitous, once we have the ability to properly look for it.

I probably should have said:

like the atomic hypothesis, together with the understanding of the microscopic quantum mechanical structure of matter did.

If we find out that there ain’t no Higgs particle and spontaneous symmetry breaking is not enough to explain a big deal of the microphysics it would of course be a surprise to many (not all…) physicists. But it wouldn’t change the world in a short time scale (like quantum mechanics did).

The next great big surprise will come, in my opinion, from neuroscience. And it’s already happening: we are finding out that it’s not that hard to interface the brain with electronics, we are now able to make neural circuits with (very simple) specific purposes, etc, etc.

What we now know is that there is a reasonable probability that in a few decades the next technological leap could be related to the use our brains to directly control electronic machines. This was unthinkable science-fiction garbage 15 years ago. It would be a really great surprise.

Once you stop taking our existence for granted,
I think the most surprising thing is that anything EXISTS at all!

I now think of the Universe as a closed multidimensional (including one or more “time like” dimensions) system, that no more has a start point than does a sphere in 3 dimensional space.

I know think of the Universe as a closed multidimensional (including one or more “time like” dimensions) system that no more a start point than a sphere in 3 dimensional space

Discovery of the remains of an advanced, industrial, nuclear-capable civilization in the deep (>50 Ma) fossil record would turn a couple of heads.

Babylon 5 reference?