There have been; 1968 was the first physical evidence supporting quarks, but the top quark wasn't observed until 1995.
That's kind of important, because a lot of effort between 1968 and 1995 went into fleshing out the theory around the quark model and confirming it, including hunting down the theorized ones not yet observed. Heck, the six quark model wasn't even proposed until the 1970s, much less confirmed.
Now, if you want to revise the question to “since 1995”...
Then we’ll talk about the Higgs boson, theorized in 1964 (just like the original quarks) but confirmed in 2012.
Maybe the issue that is that we cannot work out the theory, the equations that correctly describe it all properly. Maybe dark energy and dark matter and not actually 'other stuff' but just an indication that there are errors in our theories. Fix the theory and the 'other stuff' disappears. Quantum physics and General Relativity need to be combined at some point and doing so may resolve everything! Or it could simply be that human intelligence is not capable of finding the solution. In the same way a dog is never going to understand calculus, maybe you need an IQ of 1,000 or 10,000 to solve physics.
The premise is that antigravity is ridiculously obvious & simple to discover for almost any intelligent species, and we somehow missed it.
In general, if there was an easy way to travel between stars that we'd missed, then visitors would be everywhere, and in fact would probably have prevented humans from ever evolving undisturbed in the first place. You may say "well, what about UFOs", but as others have pointed out, society has changed recently to where billions of people have high quality cameras with them every minute of the day, and pictures of UFOs, bigfoot, etc. are still blurry and inconclusive. If they were real, we might have such pictures, but archaeologists and astronomers would have copious evidence too. It wouldn't be just hints at the fringe.
In philosophy, this is called cognitive closure. It’s possible that we humans are hitting some “edge” just like, in your example, you mentioned that a dog may never grasp calculus. To my knowledge, I’m not sure if there’s a way to scientifically test this.
Dogs may never understand calculus as you mean it but they can certainly solve related-rates problems in real time physical situations.
If the exact model is only moderately long, then we (or a Turing machine) can discover and simulate it. But it's at least conceivable that the shortest-possible exact description of physics is extremely long.
1. Either we actually have discovered all the fundamental pieces of the puzzle and there is nothing significant we still could work on so we entered the infinite journey of technological optimization. Or,
2. We have missed or misinterpreted some important pieces of the puzzle and we're stagnant until we go back and fix them so we can move forward.
This might also be because there are no new phenomena to explain. There's a lot of resistance to observing new and old phenomena because that can "disprove science", as if there's some war between science and some kind of alternative. For example, ghosts have been observed by millions, but instead of finding some solid hypotheses for these, we dismiss them as some kind of mental illness in observers. Ghost hunters use electrical signals or some similar sensors, and we dismiss them too, instead of trying to find out what is causing these signals.
A lot of scientific work still happens in fields like psychology/cognitive science, or medicine, which people intuitively feel are off. But little in physics.
You get a Nobel when you disprove what we know of physics, so it is an interesting research topic. Currently the main problem in particle physics is that everything is working too well, so nobody know where too look to find a new theoretical result.
A few years ago many people was thinking that the neutrino was a Majorana particle (in particular, in implies that the neutrino and the antineutrino are the same particle). I didn't like that idea too much [1], and luckily the experiments failed and that theory is slowly fading [2].
More recently, some other people expected that the next step was supersymmetry (the electron is a fermion, and the supersymmetry says that has a heavy version that is a boson). I liked it [1], but I think the experiments are also not favorable [2].
> There's a lot of resistance to observing new and old phenomena because that can "disprove science"
No. The LHC is working, and making observations and redoing the old calculations. Sometimes because there are new combinations of particles that nobody had seen before, sometimes because they must give some calculations to the graduate students so they can publish something.
> My theory is that after a few generations we've treated Science as a truth, and not a process.
In other comments in internet discussions I sometime get this feeling too. But don't confuse that with the attitude of the people doing research.
[1] I'm not an expert in this area, I only took a few courses in particle physics. It's more like a coffee time discussion level opinion.
[2] But you never know if experiments at higher energy will revert the trend and have results that agree with the theory.
Note that the bottom quark were discovered in 1974, and everybody expected to see the top quark then, but it was confirmed in 1995. So that push the dates at least 10 years or more.
The neutrino oscillation was discovered in 2001, and it forces a change in the "Standard model" to add mass to the neutrinos. Depending on how you count, this may reduce a few decades the time of no new things.
This year there was an announcement of a possible fourth neutrino, it's unconfirmed because they have only 4.5 sigmas, but it is very promising.