Can all our scientific knowledge crumble like a house of cards?

We are always looking for something more. And even our best guesses often do not allow us to understand where we will find it. In the 19th century, we argued about how the sun was burning - gravity or combustion, without even suspecting that thermonuclear fusion was involved. In the 20th century, we argued about the fate of the universe, not even assuming that it accelerates into non-existence. But revolutions in science are real, and when they occur, we have to revise many things - sometimes even everything - which was previously considered true.

There is a mass of fundamental truths in our knowledge that we rarely question, but perhaps we should do it. How confident are we in the knowledge tower that we have built for ourselves?

How true is our science?

According to the hypothesis of the aging of light, the numberphotons per second, which we get from each object, decreases in proportion to the square of the distance to it, while the number of objects we see increases with the square of the distance. Objects should be redder, but emit a constant number of photons per second depending on the distance. However, in an expanding universe, we get fewer photons per second over time, because they have to travel long distances as the universe expands, and their energy also decreases during the redshift process. The surface brightness decreases with distance - this is consistent with our observations.

The unexpected answer is that wehighly confident in the totality of scientific knowledge that has created. This will remain true until a certain point: until a single reliable result is achieved, which will come into conflict with our picture.

If neutrinos are faster than light, which wentconversations a few years ago turned out to be true; we would have to reconsider everything that we knew about relativity and the speed limit in the Universe. If Emdrive or another perpetual motion machine turned out to be real, we would have to revise everything we knew about classical mechanics and the law of conservation of momentum. Although these specific results were not sufficiently reliable - those neutrinos appeared as a result of experimental error, and Emdrive did not pass a test at any significance level - once we may well encounter such a result.

The most important test for will be not whether we get to such an intersection. Our true faith in scientific truth will be tested when we have to decide what to do with it.

Experimental installation of EmDrive in NASAEagleworks, where they tried to conduct isolated tests of a non-reactive engine. They found a small positive result, but it was not clear what it is connected with: with a new physics or with a systematic error. The results did not seem reliable and could not be repeated independently. Revolution has not happened - yet.

Science is both:

• A body of knowledge that encompasses everything that we have learned from observation, change and experimentation in our Universe.
• The process of constant doubt in ourassumptions, attempts to find holes in our understanding of reality, search for logical loopholes and inconsistencies and determine the limits of our knowledge in new, fundamental ways.

Everything that we see and hear, everything that ours findtools, and so on — all of which can be an example of scientific data, being correctly recorded. When we try to make a picture of the universe, we must use the full set of available scientific data. We cannot select results or evidence that are consistent with our preferred conclusions; we have to face all our ideas with every example of good data that exists. To do science well, we must collect this data, place it in pieces in a self-consistent structure and then subject it to all sorts of tests, in any conceivable way.

The best work that a scientist is capable of is to constantly try to refute, rather than prove, the most sacred theories and ideas.

The Hubble Space Telescope (left) is our largest flagship observatory in the history of astrophysics, but it is much smaller and less powerful, than the future "james webb" (in the center). Of the four proposed flagship missions for the 2030s, LUVOIR (right) is the most ambitious. By trying to reach the dimmest of the Universe, to see them in high resolution and at all possible wavelengths, we can improve and test our understanding of the cosmos in an unprecedented way.

This means increasing our accuracy to everyadditional digits after the comma, which we can only add; this means chasing higher energies, lower temperatures, smaller scales and larger sample sizes; this means going beyond the known range of confidence of the theory; this means theorizing new observable effects and developing new experimental methods.

At some point you inevitably find somethingthat does not fit into the found wisdom. You find something contrary to what you expect to find. You get a result that contradicts your old, already existing theory. And when this happens - if you can confirm this contradiction, if it withstands a thorough test and shows itself to be very, very existing, you will achieve something excellent: you will have a scientific revolution.

One of the revolutionary aspects of relativisticthe movement put forward by Einstein, but previously laid by Lorentz, Fitzgerald and others, was that fast-moving objects seemed to shrink in space and slow down in time. The faster you move relative to something at rest, the more your length will shrink and the more time will slow down relative to the outside world. This picture - relativistic mechanics - replaced the old Newtonian view of classical mechanics.

The scientific revolution nevertheless includessomething more than just the statement “the old truths are wrong!”. This is just the first step. Perhaps this is a necessary part of the revolution, but in itself it is insufficient. We could move on, just noticing where and how our old idea brings us. To push science forward — and significantly — we need to find a critical flaw in our previous way of thinking and review it until we reach the truth.

To do this, we need to overcome not one, but three main obstacles in our efforts to improve our understanding of the Universe. There are three components that are part of revolutionary scientific theory:

• It must reproduce all the success of an existing theory.
• It should explain the new results that contradicted the old theory.
• It must provide new, verifiable forecasts that have not been verified before, and which can either be confirmed or refuted.

This is an incredibly high bar, which is achieved very rarely. But when it is achieved, the rewards are like nothing else.

One of the greatest mysteries of the 1500s wasthat the planets are moving obviously retrograde - that is, in the opposite direction. This could be explained either by the Ptolemy geocentric model (left) or Copernicus heliocentric (right). However, clarifying the details with high accuracy required theoretical breakthroughs in our understanding of the rules underlying the observed phenomenon, which led to Kepler's laws and Newton's theory of universal gravity.

The newcomer, the new theory, always has a burdenproofs, replacing the former dominant theory, and this requires solving a number of very difficult problems. When heliocentrism appeared, he had to explain all the predictions of the movements of the planets, take into account all the results heliocentrism could not explain (for example, the motion of comets and satellites of Jupiter), and make new predictions such as the existence of elliptical orbits.

When Einstein proposed a general theoryrelativity, his theory was to reproduce all the successes of Newtonian gravity, and also to explain the precession of Mercury's perihelion and the physics of objects whose speed approaches light, and moreover, it needed to make new predictions about how gravity bends starlight.

This concept even extends to our thoughts aboutthe origin of the universe itself. In order for the Big Bang to become famous, it had to replace the previous concept of a static Universe. So, he had to comply with the general theory of relativity, explain the Hubble expansion of the Universe and the ratio of redshift and distance, and then make new predictions:

• On the existence and spectrum of cosmic microwave background
• On the nucleosynthetic content of light elements
• On the formation of large-scale structure and properties of the clustering of matter under the influence of gravity.

All this was required only in order to replace the previous theory.

Now think about what would be needed.to replace one of the leading scientific theories today. This is not as difficult as you would imagine: it would take only one observation of any phenomenon that contradicts the predictions of the Big Bang. In the context of GR, if you could find a theoretical consequence of the fact that the Big Bang does not match our observations, we would really be on the verge of revolution.

And that's what's important: it will not follow from this that everything on the subject of the Big Bang is wrong. The general theory of relativity does not mean that Newtonian gravity is wrong; it only imposes restrictions on where and how Newtonian gravity will be applied successfully. She will still accurately describe the Universe, born from a hot, dense, expanding state; similarly describe an observable Universe with an age of many billions of years (but not of infinite age); he will also tell about the first stars and galaxies, the first neutral atoms, the first stable atomic nuclei.

The visible history of the expanding universe includeshot, dense state of the Big Bang and the subsequent growth and formation of the structure. The complete data set, including observations of light elements and the cosmic microwave background, leaves only the Big Bang as a suitable explanation for what we see. The prediction of the cosmic neutrino background was one of the last large unconfirmed predictions arising from the Big Bang theory.

Whatever comes on this theory - whateverwent beyond our current best theory (and this applies to all scientific fields) - the first thing to do is to reproduce all the successes of this theory. Theories of the static universe, which are fighting with the Big Bang? They are incapable of that. The same applies to the electric universe and the cosmological plasma; the same can be said about tired light, about a topological defect and cosmic strings.

Maybe someday we will achieve enoughtheoretical progress, so that one of these alternatives turns into something corresponding to the full set of observables, or perhaps a new alternative will appear. But this day is not today, and in the meantime the inflationary Universe with the Big Bang, with radiation, ordinary matter, dark matter and energy explains the complete set of absolutely everything we have ever seen. And she is one of a kind, for now.

But it is important to remember that we have come to this picture.just because they did not focus on one dubious result that could collapse. We have dozens of lines of independent evidence that lead us to the same conclusion over and over again. Even if it turns out that we do not understand supernovae at all, dark energy will still be needed; even if it turns out that we do not understand the rotation of galaxies at all, dark matter will still be needed; even if it turns out that there is no microwave background, the Big Bang will still be necessary.

The universe may be completely different indetails. And I hope that I will live long enough to see the new Einstein appear, who is challenging modern theories - and winning. Our best theories are not wrong, they are just not complete enough. And this means that they can be replaced only by a more complete theory, which will inevitably include everything, in general, everything in this world - and explain it.

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