The question asks for the approximate age of the universe according to modern cosmology. This is a fundamental constant in astrophysics and cosmology, determined through various observational methods.
Correct Option: B) About 13.8 billion years
The question asks to identify the scientist who first proposed the Big Bang Theory in a scientific form. This requires knowledge of the history of cosmology and the key figures associated with the development of this theory.
B) Georges Lemaître is widely credited with first proposing the Big Bang Theory in a scientific form. In 1927, he published a paper deriving what is now known as Hubble's Law and proposed that the universe began from an initial, extremely dense and hot state, which he termed the "primeval atom."
The question asks for the strongest evidence supporting the Big Bang Theory. We need to evaluate each option based on its relevance and significance to the theory.
B) Cosmic Microwave Background Radiation (CMBR) — The CMBR is residual electromagnetic radiation from the early universe. It is a uniform glow that fills the entire sky and has a blackbody spectrum corresponding to a temperature of about 2.7 Kelvin. This radiation is interpreted as the "afterglow" of the Big Bang, representing the moment when the universe cooled enough for protons and electrons to combine and form neutral atoms, allowing photons to travel freely. The existence, uniformity, and spectrum of the CMBR were accurately predicted by the Big Bang Theory before its discovery, making it the strongest and most direct observational evidence for the theory.
The question asks about the accidental discovery of Cosmic Microwave Background (CMB) radiation and the scientists involved. This is a factual recall question related to the history of cosmology.
Correct Option: B) Penzias and Wilson
The question asks about Edwin Hubble's observational confirmation of the universe's expansion. This requires recalling the key astronomical phenomenon he studied and its implication.
Correct Option: A) Redshift of distant galaxies — Edwin Hubble's groundbreaking work involved observing the redshift of light from distant galaxies. This redshift indicated that these galaxies were moving away from Earth, and the further away they were, the faster they were receding. This observation was the primary evidence for the expansion of the universe.
The question asks about Hubble's Law, a fundamental principle in cosmology. This law describes the relationship between the velocity at which galaxies are moving away from us (recession velocity) and their distance from us. Understanding this relationship is key to determining the correct option.
B) Directly proportional to its distance. This statement accurately reflects Hubble's Law, \(v = H_0 d\), where \(v\) (velocity of recession) is directly proportional to \(d\) (distance).