Hubble's law of cosmic expansion
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Hubble's Law of Cosmic Expansion
Introduction to Hubble's Law and Cosmic Expansion
Hubble's Law, first introduced by Edwin Hubble in 1929, is a cornerstone of modern cosmology. It describes the observation that galaxies are moving away from us at speeds proportional to their distances, implying that the universe is expanding. This discovery fundamentally changed our understanding of the cosmos, leading to the development of the field of observational cosmology and the concept of an evolving universe1 2.
The Hubble Diagram and the Hubble Constant
The relationship between a galaxy's distance and its redshift is graphically represented in the Hubble diagram. The slope of this diagram is known as the Hubble constant, which quantifies the rate of cosmic expansion. Despite initial systematic errors in Hubble's distance measurements, the core observation that galaxies recede at speeds proportional to their distances remains a pivotal discovery2.
Generalized Hubble Law and Inhomogeneous Universes
Recent research has extended Hubble's Law to more complex models of the universe. For instance, a generalized linear Hubble law has been proposed for a barotropic spherically symmetric inhomogeneous spacetime. This model includes additional terms accounting for angular expansion and kinematic acceleration, which could explain large-scale matter flows without relying on Newtonian peculiar velocity models3.
Experimental Verification and Challenges
Experimental approaches, such as those involving the Mössbauer effect, have been suggested to verify the proportionality of redshift to distance, a key aspect of Hubble's Law. However, uncertainties in astronomical data and potential alternative explanations for redshift, such as the Compton effect, pose challenges to the straightforward interpretation of cosmic expansion4 10.
Hubble's Law and the Big Bang Theory
Hubble's Law is often cited as evidence for the Big Bang Theory, which posits that the universe began from a singular explosive event. However, some researchers argue that Hubble's Law does not necessarily support the Big Bang model and propose alternative explanations for the observed redshifts and cosmic expansion5.
The Hubble-Lemaitre Law Debate
There has been a proposal to rename Hubble's Law as the Hubble-Lemaitre Law to acknowledge Georges Lemaitre's contributions. Lemaitre independently derived a similar relationship between redshift and distance from general relativity. Critics argue that this renaming conflates empirical observations with theoretical derivations and overlooks the historical context of Hubble's empirical findings6 7.
Discrepancies in the Hubble Constant
Recent measurements of the Hubble constant have revealed discrepancies between values derived from the early universe (using the cosmic microwave background) and those from the late universe (using supernovae and other methods). This inconsistency, which has become more pronounced with improved measurement techniques, suggests that our understanding of cosmic expansion may need refinement8.
Conclusion
Hubble's Law remains a fundamental principle in cosmology, providing critical insights into the expanding universe. While it has been instrumental in supporting the Big Bang Theory, ongoing research and debates highlight the complexities and challenges in fully understanding cosmic expansion. As measurements and models continue to evolve, so too will our comprehension of the universe's dynamic nature.
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Hubble’s Law and the expanding universe
The Hubble Law, a key discovery in cosmology, reveals that the universe has been expanding for 14 billion years, with dark matter, dark energy, and billions of galaxies.
Hubble's diagram and cosmic expansion
Edwin Hubble's classic article on the expanding universe in 1929 introduced the concept of a galaxy's distance being proportional to its redshift, leading to modern investigations of the expanding, evolving, and accelerating universe.
Highly CitedA Generalized linear Hubble law for an inhomogeneous barotropic universe
This generalized linear Hubble law could explain the observed large scale flow of matter in a barotropic spherically symmetric inhomogeneous universe without recourse to peculiar velocity-type Newtonian models.
Expansion of the Universe
The Mössbauer effect could test the expansion of the universe, but uncertainties in astronomical data make it difficult to determine the red shift and recession velocity.
We Proof: 1. Hubble’s Law Opposes to Big Bang Theory; 2. Hubble’s Law Can Be Deduced With No Space Expansion
Hubble's law does not support the Big Bang Theory, as it does not accurately describe the expanding universe suggested by the BBT.
Redshifts and paradigm shifts; in defence of Hubble's Law
The proposal to rename Hubble's law as the Hubble-Lemaitre law is problematic from a historical and philosophical perspective, as it conflates Hubble's observation of redshift and distance with Lemaitre's universal law of cosmic expansion.
Redshifts versus Paradigm Shifts: Against Renaming Hubble’s Law
Renaming Hubble's law as the Hubble-Lemaitre law is questionable on historic, scientific, and philosophical grounds, as it conflates redshift/distance relations with cosmic expansion laws, potentially impacting current cosmic expansion puzzles.
The expansion of the Universe is faster than expected
The Hubble constant is faster than expected, with multiple independent measurements in 2019 proving a discrepancy with early Universe predictions.
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