The largest survey of physicists’ views on the fundamental questions of modern science revealed an unexpectedly weak consensus. About 1,600 participants answered questions about the Big Bang, dark matter, dark energy, and quantum gravity. Most do not regard the Big Bang as a proven absolute beginning of time, and the standard cosmological model, ΛCDM, did not even receive half the votes.

The Big Bang does not necessarily mean the beginning of time

The survey was conducted by astrophysicist Niayesh Afshordi of the University of Waterloo, science communicator Phil Halper, and Physics Magazine of the American Physical Society. More than 1,600 people took part, the majority of them researchers in physics and related fields. The authors describe the study as one of the largest surveys devoted specifically to physicists’ opinions on open questions in fundamental physics.

The most notable result concerns the Big Bang. About 70% of participants chose the wording according to which the Big Bang should be understood as a description of the evolution of the Universe from a hot and dense state, without asserting that time itself began at that moment. In the original materials from the University of Waterloo, this share is given as 68%.

This is an important clarification, because the popular view of the Big Bang often reduces the theory to a simple picture: at some point there was an ultra-dense state, then the Universe began to expand, and from that moment the history of everything that exists began. In modern cosmology, the claim is much more cautious. The theory describes the early hot and dense Universe and its subsequent evolution, but by itself it does not answer the question of whether anything — including time — existed before that state.

At the same time, the idea of cosmic inflation, that is, an extremely rapid expansion of the Universe at an early stage, received only slightly more than half the votes — 51%. This is the only other question in the survey on which a majority was obtained.

The standard model of the Universe also failed to win a majority

An even more telling result concerns ΛCDM, the standard cosmological model that has been used for decades to describe the expansion of the Universe and its main components. It assumes the existence of certain types of dark matter and dark energy and successfully accounts for a vast number of astronomical observations.

But in the survey, this model did not receive majority support. The study’s authors link some of the doubts to new observations, in particular to results from the Dark Energy Spectroscopic Instrument, DESI. They point to data that allow for dark energy’s properties to change over time, whereas the classical version of ΛCDM assumes a constant cosmological constant.

This does not yet mean that ΛCDM has been disproved. The DESI results are viewed as an indication of a possible discrepancy that will need to be tested through additional observations and analysis. The survey itself also measures scientists’ views rather than experimentally establishing the truth of any given theory.

That is why the authors interpret the lack of consensus more as a map of unresolved problems than as evidence of the failure of modern cosmology.

What physicists think about dark matter

Disagreements are especially noticeable where scientists have to explain the nature of the invisible components of the Universe.

Dark matter reveals itself through gravity, but its physical nature remains unknown. In the survey, only 17% of participants chose light new particles, such as axions, as the explanation. Another 22% pointed to the possibility of modifying the theory of gravity, including variants related to MOND or quantum gravity. The most popular single answer — about 21% — was a compromise option according to which the solution may combine several of the proposed explanations.

It is also telling that one of the former favorites — weakly interacting massive particles, or WIMPs — received only about 10% of the votes. This reflects not a lack of research in the field, but a shift in physicists’ attitudes toward specific candidates as experimental data have accumulated.

A similar picture emerges with dark energy. The cosmological constant, Λ, which lies at the core of the classical version of ΛCDM, received roughly a quarter of the votes and ended up at about the same level as the hypothesis of a dynamic field whose properties change over time.

Even quantum gravity remains an open question

There is no single answer to another fundamental problem either: how to reconcile Einstein’s general theory of relativity with quantum mechanics.

Among the proposed options, string theory leads, but it is supported by fewer than 20% of participants. Loop quantum gravity received about 12%, while 18% of respondents believe that gravity cannot be quantized at all. At the same time, the most frequent answer to the question of quantum gravity was “no opinion.”

The result is a paradoxical picture: physics possesses theories that describe enormous ranges of phenomena extremely well, yet at the most fundamental levels serious disagreements remain among researchers. And this is not about a single disputed detail, but about the origin of the Universe, the nature of dark matter and dark energy, the structure of black holes, and the relationship between quantum mechanics and gravity all at once.

For Afshordi, this is not evidence that physics has reached a dead end. In his words, scientific truth is not determined by voting, but the presence or absence of agreement helps to show where existing data are already sufficiently convincing and where there is still room for fundamentally different explanations.

It is precisely in these gaps that the next important discoveries may appear. But the survey itself does not choose a new theory in place of the old one: it only shows how far modern fundamental physics still is from a unified answer to some of its biggest questions.