The KBC Void and the Fermi Paradox: Cosmic Connections

How the KBC Void and the Fermi Paradox are connected

The KBC Void (or Local Hall) is a massive empty region of space named after astronomers Ryan Keenan, Amy Barger, and Lennox Cowie. It is centered around our Milky Way galaxy and a group of local galaxies, and has the following characteristics:

Characteristics of the KBC Void

• Size: It’s a huge area with a diameter of about 2 billion light-years
• Density: About half the average density of the Universe, with an observed relative density contrast of δ≡1-ρ/ρ0=0.46 ±0.06
• Location: centered in the Local Group of galaxies, ranging from about 40 to 300 Mpc (about 130 million to 1 billion light-years away)
• Core density: The low density at the center is measured to be about 0.25

Conflict between the KBC Void and the Standard Model of Cosmology (ΛCDM)

The existence of the KBC Void is in conflict with the current standard model of cosmology, the Lambda Cold Dark Matter (ΛCDM). The void affects the measurement of the Hubble constant, the rate of expansion of the universe, and is linked to a cosmological problem called the “Hubble tension”.

The location of local galaxy clusters in these voids can cause discrepancies between local and distant measurements of the rate of expansion of the universe. This can be due to the fact that we are in a special location that is different from the average density of the universe.

The connection between the KBC void and the Fermi paradox

The Fermi paradox is a theory that explains the paradox of our inability to make contact with alien life despite the high probability of their existence. Here’s how the KBC void and the Fermi paradox might be related:

• Spatial isolation: Our galaxy is located in a huge, low-density region called the KBC Void, which can make the physical distance to other intelligent life very large. This void is about 2 billion light-years across, making it very difficult for alien civilizations to reach us.
• Lower galaxy density: Within the KBC Void, the density of galaxies is lower than the cosmic average, which could reduce the number of planetary systems that could harbor intelligent life.
• Cosmological barriers: Civilizations located within the massive void must overcome extremely large spatial and temporal distances to communicate or travel between each other, which greatly reduces the likelihood of contact with extraterrestrial civilizations.

Modern interpretations of the Fermi paradox

Various solutions and theories have been proposed for the Fermi paradox:

• The Great Filter Theory, which states that all life must overcome certain challenges, and that at least one obstacle is nearly impossible to overcome. This obstacle prevents intelligent life from developing into a highly technological civilization.
• The Zoo Hypothesis: The theory that highly advanced alien civilizations are observing us but avoiding direct contact.
• The Dark Forest Theory: The theory that space is a dangerous and hostile environment, so intelligent life has a survival advantage by not revealing its presence.
• Rare Earth hypothesis: The theory that very few planets have the conditions to develop complex life like Earth.

The latest research on outer space (voids)

Recent research is providing new insights into the macrostructure and voids of the universe:

• Significant signals for cosmic voids have been detected through lensing of the cosmic microwave background (CMB), which are broadly consistent with the Standard Model.
• Recent findings from the Dark Energy Spectroscopic Observatory (DESI) suggest that dark energy may evolve over time, which could have major implications for our understanding of cosmology.
• It has been suggested that the study of giant cosmic voids could hold the key to solving some of the universe’s biggest mysteries.

The importance of KBC voids and the latest research

The KBC void is about seven times larger than the typical void in the universe, and it is a phenomenon that challenges a fundamental principle of cosmology: the “cosmological principle” (the assumption that matter is uniformly distributed throughout the universe). Astronomers discovered the giant void through galaxy redshift surveys, a method that creates three-dimensional maps of galaxy distribution to reveal regions with fewer galaxies.

Details of the conflict with cosmological models

The existence of the KBC void creates two major problems with the ΛCDM model:

1. Violation of cosmological principles: The remarkable lack of local holes challenges the core assumption of current cosmology that matter is uniformly distributed throughout the universe.
2. Inconsistency with simulations: Cosmological simulations, such as the MXXL simulation, show that the formation of massive low-density regions such as the KBC Void in the ΛCDM model is highly unlikely. The gravitational forces currently predicted by the model are not strong enough to form such massive and deep low-density regions.

How the Hubble Tension and the KBC Void correlate

The KBC Void provides an important clue to solving the cosmological enigma known as the Hubble Tension:

• The effects of density and gravity: Inside the KBC Void, there are fewer galaxies and matter, so gravity is weaker, while the denser regions outside the Void exert a stronger gravitational pull, pulling objects in. This creates the illusion that the local universe appears to be expanding faster than it actually is.
• Explaining the discrepancy in measurements: Scientists analyzed the density of matter in the KBC Void down to 300 megaparsecs and found it to be about 20% lower than the average density of the universe on a large scale. This lower density is associated with the phenomenon that causes the local expansion rate to be measured to be about 11% higher than the actual expansion rate.

Alternative theories and MOND

Modified Newtonian Dynamics (MOND) has been proposed as an alternative theory to explain phenomena such as the KBC void. Instead of assuming a dark matter, MOND is an approach that modifies the law of gravity itself. The main differences between the ΛCDM model and MOND are:

• MOND replaces the need for a dark matter by changing the way gravity behaves at low accelerations.
• MOND predicts that the growth of galaxies and galaxy clusters occurs more rapidly than the ΛCDM model, which increases the likelihood of voids in the MOND universe.

Gravitational alien theory

In 2021, the concept of “quiet”, “loud”, and “grabby” aliens was introduced by Hanson et al. “Grabby aliens” prevent the emergence of other civilizations within their sphere of influence, which expands at near-light speeds. It is argued that if noisy civilizations are rare, then quiet civilizations will also be rare. This theory suggests that humanity’s current stage of technological development is relatively early in the potential timeline of intelligent life in the universe.