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Finance & Accounting
Pages 3 (753 words)
1. Define dark matter and dark energy, and clearly distinguish between them. What types of observations have led scientists to propose the existence of each of these unseen influences? Dark energy is a hypothetical form of energy that permeates space and exerts a negative pressure, which would have gravitational effects to account for the differences between the theoretical and observational results of gravitational effects on visible matter.
Dark energy, which also goes by the names of the cosmological constant or quintessence, must exist due to the rate of expansion we observe for our universe. Not only is the universe expanding, but this expansion is also accelerating so the unknown 'anti-gravity' force at work is termed 'dark energy'. Some researchers are searching for an explanation that encompasses both dark matter and dark energy. One example of such a theory uses a form of energy called a scalar field (it is a field because it has magnitude, energy and pressure, but it is scalar so it has no direction). Things would certainly be easier if we didn't need to have separate theories to explain dark matter and dark energy. However, other researchers look at dark matter and dark energy as two separate problems. For example, many string theories use super symmetric particles to explain dark matter and make no connection to dark energy at all. ...
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