Which of the following best sums up current scientific thinking about the nature of dark matter?
A) Most dark matter probably consists of weakly interacting particles of a type that we have not yet identified.
B) Dark matter consists primarily of a mysterious form of energy that is causing the expansion of the universe to accelerate.
C) There is no longer any doubt that dark matter is made mostly of WIMPs.
D) Dark matter probably does not really exist, and rather indicates a fundamental problem in our understanding of gravity.
A) Most dark matter probably consists of weakly interacting particles of a type that we have not yet identified.
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Why is it difficult to observe an exoplanet directly through a telescope?
A. It is hard to see exoplanets against the blackness of space. B. Exoplanets are small compared to their parent star, so they reflect only a small portion of the star's light. C. Exoplanets tend to be far away from their parent stars, making it hard to get both the star and the exoplanet in the telescope's field of view. D. Exoplanet atmospheres absorb too much light
The pascal is a pressure unit equal to
A) 1 newton per square meter. B) 1 kilogram per square meter. C) 1 newton per square centimeter. D) 1 kilogram per square centimeter.
Interference effects are less visible for thick films because the reflected waves
A) from the bottom surface are too dim. B) become too dispersed. C) are out of phase with one another. D) are too displaced to interfere.
Wien's Law: The surface temperature of the star is 6000 K. At what wavelength is its light output a maximum? The constant in Wien's law is 0.00290 m ? K.
A. 850 nm B. 907 nm C. 311 nm D. 483 nm E. 502 nm