闪卡自测
What is the Big Bang theory?
所有闪卡
闪卡 1
问题
What is the Big Bang theory?
查看答案
答案
The Big Bang theory states the Universe originated from a very small region that was extremely hot and dense, which has been expanding and cooling for approximately 13.8 billion years.
闪卡 2
问题
True or False? The Big Bang theory states that the Universe began from a single point.
查看答案
答案
True. According to the Big Bang theory, the Universe began from a very small region that was extremely hot and dense.
闪卡 3
问题
True or False? The Universe is currently contracting.
查看答案
答案
False. The Universe is currently expanding, as evidenced by the redshift of distant galaxies.
闪卡 4
问题
What are the two main pieces of evidence for the Big Bang theory?
查看答案
答案
The main evidence for the Big Bang theory comes from:
闪卡 5
问题
How does galactic redshift provide evidence for the Big Bang theory?
查看答案
答案
Galactic redshift refers to the observation that light from distant galaxies is shifted toward longer, redder wavelengths. This indicates that distant galaxies are moving away from Earth. This provides evidence that the Universe must be expanding, which means that galaxies must have been closer together in the past.
闪卡 6
问题
What is cosmic microwave background radiation (CMBR)?
查看答案
答案
CMBR is a type of electromagnetic radiation with a wavelength in the microwave region. It is observed to be very uniform at all points in space.
闪卡 7
问题
What is the origin of CMBR?
查看答案
答案
The CMBR was originally emitted at the time of the Big Bang when the Universe was formed.
闪卡 8
问题
How does CMBR provide evidence for the Big Bang theory?
查看答案
答案
CMBR provides evidence for the Big Bang Theory because it represents the radiation emitted at the time of the Big Bang. This radiation has been redshifted to the microwave region of the electromagnetic spectrum.
闪卡 9
问题
True or False? CMBR is completely uniform in temperature.
查看答案
答案
True. CMBR has minuscule temperature fluctuations on the order of 0.00001 K, implying that objects in the Universe are uniformly spread out.
闪卡 10
问题
What is the Doppler effect?
查看答案
答案
The Doppler effect is the change in wavelength or frequency of a wave due to the relative motion between the source and the observer.
闪卡 11
问题
True or False? The Doppler effect applies to sound waves only.
查看答案
答案
False. The Doppler effect applies to both sound waves and light waves.
闪卡 12
问题
True or False? Waves emitted by a stationary object have a constant wavelength.
查看答案
答案
True. When an object emits waves, the wavefronts spread out symmetrically. This means the wavelength of the waves is constant.
闪卡 13
问题
True or False? The frequency of the sound of a moving object increases as it moves away from an observer.
查看答案
答案
False. As the object moves away from an observer, the waves spread out, so the wavelength of the sound increases and the frequency decreases.
闪卡 14
问题
What is redshift?
查看答案
答案
Redshift is the increase in the observed wavelength of a light source when it moves away from an observer.
闪卡 15
问题
What is blueshift?
查看答案
答案
Blueshift is the decrease in the observed wavelength of a light source when it moves towards an observer.
闪卡 16
问题
Which end of the light spectrum has a higher frequency, the red or the blue?
查看答案
答案
The light at the end of the spectrum with a higher frequency is blue.
闪卡 17
问题
How can astronomers determine if the light from a distant galaxy is redshifted?
查看答案
答案
Astronomers can determine if the light from a distant galaxy is redshifted by:
闪卡 18
问题
What does the observation of redshift from distant galaxies imply about the Universe?
查看答案
答案
The observation of redshift from distant galaxies implies that the Universe is expanding.
闪卡 19
问题
True or False? The greater the distance to a galaxy, the greater the redshift observed.
查看答案
答案
True. The greater the distance to a galaxy, the greater the redshift observed, indicating that the galaxy is moving away faster.