8.2 Red-Shift Flashcards

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1
Q

what is red-shift?

A

an observed increase in the wavelength of light from distant galaxies.

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2
Q

what two things can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?

A
  • the further away a galaxy is, the faster it is moving
  • the further away a galaxy is, the greater the observed increase in wavelength
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3
Q

what does the big bang theory suggest?

A

the entire universe started from a very small, hot and dense region in space.

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3
Q

what did scientists observe to provide evidence that the universe is expanding at an even faster rate?

A

they observed supernovae, which suggested that galaxies are moving away at an even faster rate.

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3
Q

why does red-shift provide evidence for?

A
  • provides evidence that the universe is expanding
  • supports the big band theory
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4
Q

compare the observed red-shift of two galaxies, one further away than the other.

A
  • the galaxy that is further away is travelling faster
  • the observed red-shift is greater the further away it is
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5
Q

prior to observations of supernovae, what was belived about the rate of expansion of the universe and why?

A
  • the rate of expansion was expected to occur at an even slower rate
  • it was thought that gravitational forces would cause this slowing down
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6
Q

what two ideas could explain the universe’s ever increasing rate of expansion?

A
  • the existence of energy and mass that we can’t detect, known as dark matter and dark energy
  • these ideas are still being developed by scientists and are not yet fully understood
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