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Transcript of Universe
of ongoing controversy. In the 1920s, US astronomer Edwin Hubble observed a critical phenomenon that
increased our understanding of the universe. Using a powerful new telescope, he
identified a group of celestial objects outside our own galaxy. Hubble’s observation led to the assumption that at some point, all matter in the
universe was close together. The event that started its expansion is referred to as
the Big Bang. The Big Bang theory has led to many predictions in science. Physicist George Gamow
realized in the 1940s that the early universe must have been extremely hot and
dense. As the universe expanded, it would cool down, and the initial hot radiation
should eventually be observable as uniform radio waves throughout space.
In the 1960s, Robert Wilson and Arno Penzias discovered cosmic uniform radio
waves that implied a temperature of about 3 degrees above absolute zero (Kelvin). On the other hand, some people, like the Greek philosopher Aristotle, did not
like the idea of the universe having a beginning. He preferred to believe that
the universe had existed and would exist forever and that it was eternal and
perfect. (작가,화가) 파 What is the belief held by the religious circles regarding the origin of the universe? One thing that these two schools of thought originally had in common was
that no matter what the origin or the ending of the universe, the universe
itself was static and unchanging. In fact, this was a natural belief to have since
recorded history is so short that the universe has not changed significantly in
all that time. How was Aristotle's idea of the universe different? What did the two sides have in common? And why was this an accepted belief? 정지 상태의, 고정된 regardless of The Two Different Beliefs
About the Universe Q. Q. Q. In particular, debate has centered around
how—or if— it began. One school of thought, especially held by Jewish,
Christian, and Islamic religions, is that the universe was created. Thus,
there was a time when there was no universe, and equally, there will be
a time when there will be an end to the universe. the Apocalypse In the 19th century, evidence began to challenge the idea of a motionless,
unchanging universe. At this time, Boltzmann, the German physicist, formulated
the Second Law of Thermodynamics. This states that the total amount of entropy, or
disorder, in the universe always increases with time. Therefore, the universe must be
changing in some way for its entropy to increase. Also, according to Newton’s Law of
Gravity, each star in the universe ought to be attracted to each other and thus start
falling together and collapsing at a central point. If the universe were motionless, the
result would be an unavoidable collapse. static (thermo): heat 열역학 What is entropy? order disorder chaos What prevents the universe from collapsing? 피할 수 없는 붕괴 Was there a beginning or
did it exist from the start? By observing the Doppler Shift of these stars—the way the wavelengths and colors
of their light changed due to their motion—he realized that they were receding from
our own position in the universe. In fact, all the observable galaxies were moving
away from each other! Furthermore, the more distant the galaxy, the faster it was
moving away. This observation implied that the universe was expanding. (very important event) pl. phenomena 하늘의, 천체의 celestial bodies: 천체의 은하계 a large system of stars Doppler Effect The Doppler effect can be observed for any type of wave - water wave, sound wave, light wave, etc. We are most familiar with the Doppler effect because of our experiences with sound waves. Perhaps you recall an instance in which a police car or emergency vehicle was traveling towards you on the highway. As the car approached with its siren blasting, the pitch of the siren sound (a measure of the siren's frequency) was high; and then suddenly after the car passed by, the pitch of the siren sound was low. That was the Doppler effect - an apparent shift in frequency for a sound wave produced by a moving source.
The Doppler effect is of intense interest to astronomers who use the information about the shift in frequency of electromagnetic waves produced by moving stars in our galaxy and beyond in order to derive information about those stars and galaxies. The belief that the universe is expanding is based in part upon observations of electromagnetic waves emitted by stars in distant galaxies. Furthermore, specific information about stars within galaxies can be determined by application of the Doppler effect. Galaxies are clusters of stars that typically rotate about some center of mass point. Electromagnetic radiation emitted by such stars in a distant galaxy would appear to be shifted downward in frequency (a red shift) if the star is rotating in its cluster in a direction that is away from the Earth. On the other hand, there is an upward shift in frequency (a blue shift) of such observed radiation if the star is rotating in a direction that is towards the Earth. to move away 별들의 빛의 파장 및 색깔 sound wave
water wave expanding What is significant about Hubble's observation? Q. According to the Big Bang theory, time and space did not exist prior
to the beginning of the expansion. This is science's way of explaining
how the universe began to exist. uncountable rapid expansion of
space and time Interestingly, there really wasn’t any sort of explosion (or bang) as the name suggests, but rather the rapid expansion of space and time. It is like blowing up a balloon, as you blow air in, the exterior of the balloon expands outward. The theory asserts that our entire universe was created when a tiny (billions of times smaller than a proton), super-dense, super-hot mass exploded and began expanding very rapidly, eventually cooling and forming into the stars and galaxies with which we are familiar. This event is said to have happened approximately 15 billion years ago. Rather than expanding outward into some preexisting vacuum, the event of the Big Bang was space itself expanding - perhaps at speeds greater than light. Thus, the age of the universe can be calculated
from the distance and the velocities of the stars traveling away from us. mass super-hot
super-dense Rather than expanding outward into some preexisting vacuum, the event of the Big Bang was space itself expanding. 100억 에서 200억 년 사이 Due to experimental uncertainties, a definite age still cannot be given for the
universe; however, the age of the universe is calculated to be between ten to twenty
billion years old. What is the basis of the underlined sentence? 균일한 even and regular
throughout 밀도가 높은 compact Growth has not been ___________ across the country. 성장이 전국적으로 균일하지 않다 uniform Another interesting result of the Big Bang theory relate to the movement of the
galaxies. Though the universe is expanding, the galaxies themselves are not moving.
Instead, it is the space between the galaxies that is expanding, while the galaxies
themselves remain still. It's much like points drawn on the
surface of a balloon. When the balloon
inflates, only the material stretches out
and eparates the points. The points
themselves do not actually move. What makes the galaxies look like they are actually moving? 부풀다 근거,이유 Later, technology enabled scientists to take very detailed measurements of this
radiation. They confirmed that it is extremely uniform, is of the shape predicted by
theory, and has a temperature of 2.7 degrees Kelvin. This observation provides
strong support for the Big Bang theory. 우주의 What does this discovery mean? It means that there was a super-hot and super-dense mass in the beginning. 절대영도 보다 3도 높은 This supports the Big Bang Theory!!! uniform radio waves throughout space very hot & dense
universe expand cooled
down uniform radio waves
spread in space evidence of the Big Bang Theory 1 Theory 2 Galaxies appear as though they are moving but
they are actually NOT. It's the space that is expanding.