There is no shortage of debate about the nature of dark matter, a mysterious substance that many believe makes up a large proportion of the total mass of the universe, in spite of never having observed it directly. Now some believe that Landauer’s principle, which dictates the physical nature of information, is raising a startling possibility: that dark matter might be information itself, writes Melvin Vopson.
One of the greatest curiosities of modern physics is the nature of the mysterious substance known as “dark matter”. It is widely accepted that the make up of the Universe is about 5% ordinary (baryonic) matter consists of baryons — an overarching name for subatomic particles such as protons, neutrons and electrons, 27% dark matter and, 68% of the universe is made of something even more puzzling called “dark energy”. Unlike normal matter, dark matter does not interact with the electromagnetic force. This means it does not absorb, reflect or emit light, making it extremely hard to spot.
Dark matter was first suggested in 1920s to explain observed anomalies in stellar velocities, and later in the 1930s, when Fritz Zwicky, a Swiss astronomer noted a discrepancy between the mass of visible matter and the calculated mass of a galaxy cluster as well as a discrepancy between the motion of a cluster of galaxies was much too fast to be held by gravitational attraction of visible matter alone. The existence of this gravitational anomaly, Zwicky termed dunkle Materie - 'dark matter.' However, the strongest scientific argument for dark matter’s existence came in the 1970s with the work of the US astronomer Vera Rubin, who showed a consistent effect of spiral galaxies rotating too fast for the amount of visible matter present. Both Rubin and Zwicky had observed something adding to the force of gravity impacting these galaxies.
The main observational evidence in the 1970s came from researching galaxy rotation curves. Studying galaxy rotation curves allows the study of the kinematics of galaxies, and provides a way to estimate their masses. The orbital velocity of a rotating disk of gas and stars is expected to obey Kepler's second law, so the rotation velocities should decline with distance from the centre. Experimental observations indicate that the rotation curves of galaxies remain flat as distance from the centre increases. Since there is more than expected gravitational pull if only the observed light / baryonic matter of a galaxy would be present, the flat rotation velocity curves are a strong indicator that something else is there, termed dark matter.
Predicted and observed galaxy rotation curve of a spiral galaxy. Dark matter is needed to explain the 'flat' rotation velocity curve even for stars located at very large distances from the galactic centre. Credit: www.resonance.is
Although the existence of dark matter is generally accepted, a significant community of scientists are working on alternative explanations that do not require the existence of dark matter at all. To this end, there are various theoretical approaches, usually involving modifications of the existing established theories such as modified Newtonian dynamics, modified general relativity, entropic gravity and tensor-vector-scalar gravity, to name a few.
Some have proposed that “information” is the 5th state of matter along solid, liquid, gas and plasma and possibly the dominant form of matter in the universe
Most physicists today are trying to identify the nature of dark matter by a variety of means, but the consensus is that dark matter is composed primarily of a not yet discovered subatomic particle. Unfortunately, all efforts to isolate or detect the dark matter have failed so far.
Could the explanation of “dark matter” mystery come from a totally new approach, based on Information Physics?
The research field of information physics has its origins in the principle that information is physical, the information is registered by physical systems, and all physical systems can register information. The interplay between physics and information has been a topic of scientific debate since late 1920s. Leo Szilard analysed the relationship of information to physical processes, demonstrating that information about a system dictates its possible ways of evolution, and offering an elegant solution to Maxwell’s Demon famous paradox. The information content of the universe has been addressed in several studies by the likes of Stephen Hawking, Jacob David Bekenstein and Seth Lloyd going back as far as late 1970s and more recently in a 2021 study.
The strongest scientific argument for dark matter’s existence came in the 1970s with the work of the US astronomer Vera Rubin, who showed a consistent effect of spiral galaxies rotating too fast for the amount of visible matter present
With the emergence of digital computers, digital technologies and digital data storage, the topic of information physics entered a new era, beginning with the pioneering information physics work of Brillouin in 1953 and Landauer in 1961. They both demonstrated that information is not just a mathematical construct, but it is physical. Following its experimental confirmation, Landauer’s principle, which dictates the physical nature of information, is becoming widely accepted as valid by the scientific community today.
In 2019, an extension of the Landauer’s principle, called the mass-energy-information (M-E-I) equivalence principle, was proposed. The M-E-I equivalence principle states that, if information is equivalent to energy, according to Landauer, and if energy is equivalent to mass, according to Einstein’s special relativity, then the triad of mass, energy and information must all be equivalent, too. According to the M-E-I equivalence principle, a bit of information must have a small mass when information is stored at equilibrium. The information bit has therefore the characteristics of a scalar boson particle with no charge, no spin, no any other properties except mass / energy. Such information particle would display its presence only via gravitational interactions, but it would be impossible to detect because it would not interact with the electromagnetic radiation. These are in fact the characteristics of the elusive “dark matter” whose presence is inferred only from gravitational interactions, but has never been observed or detected.
This led some to propose the radical idea that information might be the missing dark matter in the universe, and also to postulate that “information” is the 5th state of matter along solid, liquid, gas and plasma and possibly the dominant form of matter in the universe.
Artistic representation of a digital blueprint of the Universe. Free licence picture from Pixabay.com
Assuming a constant average temperature T = 2.73K of the universe (temperature of the cosmic microwave background) and without making any considerations of where this information mass is localized in space-time, a rough estimation indicates that a total number of ~ 52 ´ 1093 information bits in the visible universe would be sufficient to account for the entire missing dark matter. This raises an astounding possibility: that dark matter might be information itself.
Although the proposed theory has speculative aspects, it has the virtue of being verifiable in a laboratory environment. In fact, a new experiment has already been proposed in March 2022 and the World’s first Information Physics Institute (IPI) has been recently created to support these studies and the experimental efforts at the University of Portsmouth, via fundraising and collaborative research. The hope is that the IPI initiative and the field of Information Physics research will soon yield important results that will advance our understanding of the universe and its governing laws.
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