We continually read news about new findings that they defy the known physics of the Universe. This may lead us to ask ourselves something: do we know so little about the Universe that absolutely everything challenges it? To answer this question it is important to give a little context. Yes, a lot is known about astrophysics, but when we talk about something as immense as the Universe, even that “a lot” can fall short.
Furthermore, much of this information is based on hypotheses that have been accepted as consensus, but not on absolute truths. Therefore, it is not strange that in the largest survey ever conducted It has been proven to astrophysicists and astrophysics fans that there is a lot of disagreement on almost everything related to the cosmos.
The largest survey. In 2024, during an astrophysics conference in Copenhagen, a survey was carried out in which 85 experts participated. All of them had to answer a series of questions about some of the best-known theories in astrophysics. With this survey it was seen that there is a lot of disagreement, even in those theories in which there is supposed to be a great consensus.
In order to check whether these disagreements were a result of the sample size, a new survey was carried out in 2025, this time with 1,600 people who had to answer 11 questions. Some participants were experts from the American Astrophysical Society. Others were amateur readers of Physics Magazine. With a larger sample, the results were very similar. There is very little consensus.
From hypotheses to certainties. Science in general, and astrophysics in particular, is built on hypotheses that evolve as scientific advances are made. For this reason, it is often more full of probabilities than certainties. It is important to differentiate different branches of science. In health sciences, there are certainties. For example, we know that antibiotics attack bacteria and are not useful against viruses, no matter how many people insist on taking them for the flu. We also know that their abuse can be very harmful, since it contributes to the development of resistance in bacteria. Those are certainties, although logically there is also information that evolves over time.
In astrophysics, hypotheses accepted by consensus often outnumber certainties. There are very clear certainties, such as that the Earth is not flat or that it revolves around the Sun. But also some hypotheses with which not even experts agree.
Cosmic inflation wins. The issue on which there was the greatest consensus in the 2025 survey, the results of which were recently published, was cosmic inflation. That is, the hypothesis that points to an exponential expansion of the Universe which began in its first moments, after the Big Bang. 51% of respondents agreed that this theory explains many problems in cosmology at once and therefore has a high probability of being true.
Talking about the Big Bang. The existence of the Big Bang was another of the theories with the greatest consensus in the survey, although the truth is that the figure is nothing to write home about either. 25% of the participants agreed that this event gave rise to the Universe 13.8 billion years ago. On the other hand, there were 68% of people who indicated that the Universe was born at a time when there was a large increase in temperature and density, but they did not indicate when that occurred.
Disagreements with dark matter. Gravitational behaviors that do not respond to the observed mass have been observed in the Universe. That is, it seems as if there are massive objects exerting a gravitational attraction on others, but these objects are not detected, not even large accumulations of atoms. There is nothing. 27% of those surveyed consider that this can be explained by the existence of dark matter. However, there are 12% who believe that all this may be due to changes in the behavior of gravity on cosmic scales. That is to say, when we talk about the immensity of the Universe, the gravity exerted by objects is not the same.
On the other hand, there are 5% of people who consider that the key is in primordial black holes. Although here we must emphasize that one of the hypotheses about the origin of dark matter is that it is formed in part by primordial black holes, so they would not be denying its existence.
String theory to solve incompatibilities. The theory of general relativity was proposed on large, cosmic scales. On the other hand, quantum mechanics talks about the behavior of matter on a subatomic scale. Both questions seem incompatible, but to understand the Universe we need to work at both scales. Therefore, for a long time there has been thought about a theory that helps unify both issues. This, for 19% of those surveyed, is string theory. In it, subatomic particles, instead of being treated as points, are considered vibrational states of a more basic extended object, called a string.
Normally, when we try to calculate the energy of a particle by considering it a mathematical point, without extension, we get closer to it eternally. We can do a kind of infinite zoom. On the other hand, when the points are replaced by strings with a minimum length, a result must necessarily be obtained. It does not tend to infinity. On the other hand, in string theory gravity, which not normally considered on a quantum scalearises naturally.
Another hypothesis. The point is that, in the survey we are talking about, there are 12% of people who consider that string theory does not solve the problem, but that another theory does: that of loop quantum gravity. This, basically, acts in a completely opposite way. String theory emerges with quantum mechanics as a starting point and tries to find ways to make gravity make sense.
On the other hand, the theory of loop quantum gravity starts from the General Theory of Relativity and attempts to quantize it in a way that makes sense. In other words, string theory goes from the smallest to the largest and loop quantum gravity goes from the largest to the smallest. They are opposite and opinions about them are very divided.
Fans also control. Something interesting about this survey, compared to the one in Copenhagen, is the fact that it also includes fans. And the most curious thing is that the results do not vary too much. The same disagreements remain. Fans have the same doubts as experts. And the thing is, in astrophysics, there are many doubts. But that is precisely what makes each discovery so exciting that it helps dispel a few of them.
Image| NASA/Magnific | POT
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