# Pavel Kroupa

Pavel Kroupa (born 1963) is a Czech-Australian astrophysicist, who since 1999 has worked on cosmology and challenges to dark matter theory.

## Sourced

* The currently (2010) widely accepted/believed description of the birth and evolution of the universe and of its contents is "Lambda Cold Dark Matter Concordance Cosmological Model" (LCDM CCM) … My own research was very much confined to the early version of the LCDM CCM (mid-1990's) when I began performing numerical experiments on the satellite galaxies of the Milky Way. I was quite happy with the CCM, as everyone else, and did not bother with the fundamental issues raised by some. With time, however, it became apparent that the LCDM CCM accounts poorly for the properties of the satellite galaxies and their distribution about the Milky Way. Warm dark matter models fared no better.
** Pavel Kroupa: Dark Matter, Cosmology and Progress website (July 4, 2010).
* For me MOND is just as nonstandard as ΛCDM.
** Pavel Kroupa (in debate with Simon White) Dark Matter - The Debate - YouTube, uploaded on Dec 31, 2010
* MOND works far too well! In fact, just as planetary systems are Keplerian objects, galaxies are Milgromian objects. Milgrom’s discovery of a$_0$ is likely as epochal as Planck’s discovery of h.
** Pavel Kroupa: The Dark Matter Crisis website (21 March 2011).
* The current standard model of cosmology (SMoC) requires The Dual Dwarf Galaxy Theorem to be true according to which two types of dwarf galaxies must exist … The Dual Dwarf Galaxy Theorem is falsified by observation and dynamically relevant cold or warm DM cannot exist. It is shown that the SMoC is incompatible with a large set of other extragalactic observations.
** Pavel Kroupa (2012). "The dark matter crisis: falsification of the current standard model of cosmology". arxiv.org: abstract.
* The existence of dark matter particles can never be disproven by direct experiment because ever lighter particles and/or ever smaller cross sections just below the current detection threshold may be postulated for every non-detection. There exists no falsifiable prediction concerning the DM particles.
** Pavel Kroupa (2012). "The dark matter crisis: falsification of the current standard model of cosmology". arXiv.org: page 28.
* Galaxies are observed to be simple systems following laws that result from scale-invariant dynamics which do not emanate from the haphazard merging history of halos of exotic dark matter.
** Pavel Kroupa (16 Oct. 2014). Do astronomical data contradict the existence of dynamically relevant cold or dark matter? (seminar talk at Columbia U. Astronomy Department).
* The existence of exotic dark matter particles outside the standard model of particle physics constitutes a central hypothesis of the current standard model of cosmology (SMoC). Using a wide range of observational data I outline why this hypothesis cannot be correct for the real Universe.
** Pavel Kroupa (2014). "Lessons from the Local Group (and beyond) on dark matter". arXiv.org.
* The first step is that we need to revisit the validity of Newton’s universal law of gravitation. Starting in the 1980s, Mordehai Milgrom at the Weizmann Institute in Israel showed that a small generalisation of Newton’s laws can yield the observed dynamics of matter in galaxies and in galaxy clusters without dark matter. This approach is broadly known as MOND (MOdified Newtonian Dynamics). Milgrom’s correction allows gravitational attraction to fall off with distance more slowly than expected (rather than falling off with the square of distance as per Newton) when the local gravitational acceleration falls below an extremely low threshold. This threshold could be linked to other cosmological properties such as the ‘dark energy’ that accounts for the accelerating expansion of the Universe.These links suggest a deeper fundamental theory of space, time and matter, which has not yet been formulated.
** Pavel Kroupa (November 2016). "Has dogma derailed the scientific search for dark matter?". aeon.co.
* Community Reactions: "You are un-hireable" My (counter)Reaction: 1) "There is something not quite right with the community" 2) "Once one leaves the dark matter framework, real and correct predictions become possible"
** Pavel Kroupa: On the Non-Existence of Dark Matter. YouTube, Astrofisica UC (October 10, 2021). (quote from slide at 11:46 of 1:57:00)
* ... MOND is the one theoretical description of gravitation which offers the greatest number of predictions which have been verified ...
* (22 January 2024)"CMC2024: Pavel Kroupa - Dark Matter doesn't EXIST || Talk 01". Physics Research with Leo Kapp, YouTube. (quote at 17:35 of 29:45 in video)

## See also

* Modified Newtonian dynamics