Our best, most current, most accurate, and most predictive theories are not fundamentally true.
Less than 400 years ago with the publication of the Principia in 1687, Isaac Newton shook the global scientific community, put the final nail in the coffin for geocentrism, and revolutionized humanities conception of reality with his universal law of gravitation and other laws of motion.
Finally the movements of the planets and falling objects like apples were conceptualized under a unified mathematical framework.
Unfortunately, his equations were wrong.
If we use Newton’s laws of motion to calculate positions on earth using our GPS satellites, it would start out alright…but by the end of a single day they would be off by miles. 
They also give very close, but still incorrect answers to how Mercury’s elliptical orbit changes over time. 
Using his equations to make predictions of objects around black holes or moving near the speed of light yields even more inaccurate results.
Essentially, if you’re trying to answer questions about objects moving at extremely high velocities or in extremely strong gravitational fields, Newton’s equations simply give you the wrong answers.
If only there were a super genius that could invent new interpretations of light, mass, space, and time, that fixes all of these problems…
Einstein’s theories of special and general relativity explain all of these discrepancies of Newton’s laws. They give the correct solution to Mercury’s orbit, we adjust the clocks on GPS satellites to account for time dilation, and relativity exquisitely describes the motions of object and warping of spacetime near black holes and near the speed of light.
But even relativity falls apart at the extremes.
Einstein’s equations don’t describe what happens in the singularities of black holes, and though you can use them to accurately rewind the clock of physics to mere fractions of a fraction of a second after the big bang, they break down there as well.
Our two best theories of physical reality are quantum mechanics (for the very tiny and probabilistic) and relativity (for the very massive and/or very fast), and they currently use fundamentally different kinds of mathematics in their conception. Despite being our best, most predictive, most validated theories, they don’t speak the same mathematical language.
In some sense, we know they are both wrong because they are both so right, but fail to take each other into account.
In physics, when equations start to give you infinites and your best theories are misaligned, it’s a sign that new ideas are needed.
How can we possibly be okay with our best theories being wrong?
“All models are wrong, but some are useful.” - George E.P. Box
Though both Einstein’s and Newton’s equations are wrong at a fundamental level, the fact of the matter is that they’re still exceedingly useful. They’re still excellent approximations for reality and make impressively accurate predictions, within certain bounds.
In fact, we still use Newton’s laws when planning the ridiculously complex decade long trajectories for space missions, including the gravitational assists from planets.
We use Einstein’s equations for our GPS, to understand gravitational redshift of light, and to interpret gravitational lensing, because they work.
Even geocentrism is useful if you’re trying to predict the location of planets in the night sky (though if you’re planning on launching something to them, you’ll probably want to use heliocentrism…).
The resolution of scientific insight increases over time.
As experiments have yielded new evidence for the structure of the atom, we’ve grown and adapted our best theories to more accurately describe what we’ve found and to make predictions about what we could find.
We will never un-discover atomic structure, though in the future our model is likely to again be enhanced in light of new evidence. We also won’t un-discover gravity, though again, it’s highly likely our best conceptions will eventually need to be updated.
Our current best theories are our current best theories because they explain the evidence we see, and make predictions that have only ever been validated.
For example, with relativity there is no experiment in disagreement with its explanations or predictions, and it was most recently validated with the measurement of gravitational waves in 2015. Though his equations predicted their existence in 1916, even Einstein thought they would always be beyond our ability to measure.
Each subsequent theory, whether for gravity, atomic structure, or just about anything else, has been less wrong than the ones before.
Relativity encompasses Newton’s laws…they can be derived from Einstein’s equations.  The quantum model of the atom encompasses and better explains the plum pudding, nuclear, and planetary models.
Finding discrepancies between predictions and experimental evidence is a scientific triumph rather than a failure, as it represents a new platform on which to further our understanding.
We can never prove anything to be true.
We spiral inwards towards what is true through the process of successive scientific falsification…aka rejecting the null hypothesis.
Newton didn’t know about the speed of light or the fact that things like neutron stars and black holes exist. But he did know that “if [he had] seen further, it is by standing on the shoulders of giants”.
These insights triggered successive ontological reawakenings for humanity and uncovered new understanding which we set foot upon today in our endeavor to see further still.
Newton was wrong and so was Einstein, and that’s okay because their insights are fundamentally important steps towards a more fully accurate understanding of reality and our existence.
Drafts and edits found here.