The Nature and Beginnings of Science

Posted on February 19, 2022 by parallaxHubble
The Bible and a Microscope, Religion and Science – Adversaries or Allies?

Ever since the development of the rational brain, human beings have tried to understand the world around them. For the first few millennium, we went about understand the world around us through story and narration. Whether or not you consider yourself religious, it is evident that prominent religious works, such as the Bible of Christianity, the Quran of Islam, and even further back, the ancient Egyptian characters of Set, Osiris, and Horus, served to not only represent religious ideals but also guide our pre-modern humans on how to best live life and approach the necessary uncertainty, suffering, and pain involved. (source)

Set and Horus, Egyptian Gods of Evil and Protection, In Battle

As Karen Armstrong argues in her NY Times article, these texts were not necessarily meant to be taken at face value. Instead, she asserts, they require a more fluid, mystical understanding, one that places value on the concept and theme rather than the exact detail being used to express that theme. An example would be that one can deduce from the battle between Set, the ancient Egyptian god of evil, and Horus, the ancient Egyptian god of war and Protection, that dealing with evil in our own lives will be harmful, even to a god, as Horus lost an eye while fighting Set.

However, as society developed, and the framework of Christian religion spread across Europe, the need for such texts as a means to guide one’s life decreased. Due to a combination of technological advancements, improved order and societal structure, some of which provided by the framework of religion, prominent thinkers began looking beyond the Bible for answers about our world, specifically the natural world. Great 17th and 18th century scientists such as Isaac Netwon, Galileo, Watt, and Herschel come to mind. Consequently, the nature of science was defined by existing purely in the realm of facts. In science, something is either a true statement or a false statement. This is the rational basis that continues to modern times, where experiments are conducted to test whether or not a hypothesis is false or true. Compared to the nature of religion, which exists rather in the abstract, in the mystical, science offered a much more concrete, undeniably verifiable way of looking at the world, one that continues to this day.

The Scientific Method

Although many believe the nature of science to be completely independent from that of religion, I disagree. I view both as simply two tools used to help us interpret, understand, and ultimately endure the world around us. Each one has its strengths, it weaknesses, and its purpose in human society and ultimately ourselves.

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The History of Gravity

Posted on February 19, 2022 by jschorr21
Curvature of Space-time, from iStock

Gravity has been a mystery for most of human history, and it was only recently(about 350 years ago) that the first gravitational theory was published. Gravity was always thought of as a force that brought things to their “natural place.” But when Copernicus came up with his idea for a heliocentric solar system, a theory of gravity was needed to explain things. Galileo hypothesized that gravity depended on mass and not much else. Then in 1687, Issac Newton was hit on the head by a falling apple, and his gravitational theory was born. He saw an apple falling, and thought, how could these objects start falling from rest without a force pulling them? He also realized that the moon wouldn’t stay orbiting earth if there wasn’t some force keeping it in orbit. He found that the force between two objects would be the produced of their masses, and would be inversely proportional to the square of the distance between the two objects. This gravitational theory became the basis for science, physics, math, and astronomy for the next few hundreds of years. For example, Newton’s idea of gravity led to the discovery of Neptune, as scientists found that the orbit of Uranus was influenced slightly by an outside source.

In 1916, Albert Einstein presented another level to Newton’s gravitational theory, The General Theory of Relativity. While Newton believed space and time to be fixed in place, Einstein believed them to be malleable. Einstein hypothesized that gravity is actually the warping of space and time together. The more massive an object, the more space-time would be warped. This theory explained many things that Newton couldn’t, like why light bends around massive objects, and why clocks run at different speeds based on their positions relative to Earth’s surface. His theory also predicted black holes, which are regions of mass that are so dense that even light cannot escape them, hence the name “black holes.”

Einstein’s theory had two main points: The first was that the laws of physics are the same as long as an object is not accelerating. For example, when inside of a moving train, the laws of physics are the same. And second, that the speed of light is always the same speed of 300,000km/sec, no matter how fast the observer is moving. He also described what is now known as “time dilation.” So if you are traveling in a fast rocket, and pass a slower rocket with a clock inside, that other clock would be tickling slower than yours. Likewise, if you brought a clock to the top of a mountain, it would tick slower since the strength of gravity is slightly less. Back to the rocket scenario– the slower rocket would seem shorter in comparison to yours, and the faster you go, you and your rockets mass will continually increase. Essentially, as your speed increases, so does mass, needing you to provide increasing energy. This is why we cannot ever reach the speed of light. To reach the speed of light, you’d need an infinite amount of energy. Einstein also created his famous matter-energy equation, e=mc^2. Because the speed of light is huge, a small amount of mass can be converted into a large amount of energy. This theory has been proven over the years through experiments involving synchronized clocks in planes, and the fact that ripples in the fabric of spacetime(gravitational waves) were found in 2016.

Einstein’s theory has been incredibly essential to our modern world. Some things that would be impossible without the idea that matter can be converted into energy include Nuclear Power Plants and nuclear weapons. Additionally, GPS systems could never work without knowledge of general relativity.

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Galileo and the Telescope

Posted on February 18, 2022 by evang914
Illustration of Galileo looking through his telescope, via Biography.com

Galileo and the telescope have become synonymous over the ages. It’s difficult to think of one without also considering the other. But it was not Galileo who invented the telescope– although he was one of a few who revolutionized its use for astronomy. The telescope’s origins can be traced back to English philosopher Roger Bacon in the 13th century, and even before that to Islamic scientists during the 10th century. However, up until Galileo’s time, telescopes had mainly been used for terrestrial observations.

When Galileo learned of a “Danish perspective glass in 1609,” he went about designing his own telescope. His initial design could only magnify objects 3x, but he continued refining his work to eventually reach a magnification of 30x. It was with these designs that he was able to make the celestial observations that the moon was not a perfect sphere, moons orbited Jupiter, and blemishes existed on the sun– all vitally important discoveries cementing his place in the history books of astronomy.

But in some cases, Galileo wasn’t the only, or even first, to make these observations. Galileo achieved fame partially because he quickly published and shared his observations. English astronomer Thomas Harriot made the first recorded observations of the moon a month before Galileo made his own. Harriot’s maps were also more detailed than Galileo’s and included more information, but because he did not publish and distribute his findings, few remember his work.

Source: Library of Congress

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Retrograde motion

Posted on February 18, 2022 by joubertklopper

Like the ancients Greeks, I also had some trouble understanding retrograde motion and how it’s possible that it might seem that some objects in the sky move in reverse motion. Instead of rising in the east and setting in the west, it appears that some objects move in reverse from west to east for a period of time. After studying this object in the textbook, I understand that retrograde motion is caused not by the physical movement of the object which appears to move in reverse, but rather a change in our position as the observer. This principle is called the stellar parallax. It turns out that retrograde motion is caused when earth passes by another planet in its orbit which creates the apparent retrograde motion. This was a problem for ancient people (greeks) to comprehend, because they assumed earth was the center of the universe.

Retrograde motion

As seen in the figure above, earth passing by Mars in its orbit causes the apparent retrograde motion for the observer located on earth.

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What makes the Tides happen?

Posted on February 17, 2022 by Johann West

This blog will be referencing information sourced from the Tides: Crash Course Astronomy #8 video. We know that mass has gravity, and more mass had more gravity. This raises the question, why does the moon have a greater impact on the Earth’s tides than the Sun, even though the Sun has such a greater gravitational force? This is because of the close distance to the Earth the Moon has. Think of the gravitational effect that causes the tides as the Earth stretching. As shown in the picture above, the side of the Earth the is closer to the moon gets stretched towards the moon because of the Moon’s gravity. This causes a bulge, making the Earth slightly football shaped. You may be wondering why in the picture both sides of the Earth appear to be bulging then, since the Moon is pulling on the near side of the Earth. This is because the center of the Earth is also getting pulled slightly, while the far side of the Earth stays in place. This creates the effect that makes it look like both sides are getting pulled on. This stretching is what causes the tides. The gravity stretches the oceans. When you are on the side of the Earth getting stretched, you experience high tide, you can visualize the oceans stretching farther onto shore. Then the Earth rotates, and you experience low tide, and the oceans recede because you are on the side of the Earth that is not getting stretched. Then high tide again, then low tide. This is why there are two high tides and two low tides everyday. This affect of the tide seems to only be meaningful on large objects, like the ocean. Humans and other small things are not affected. However, the Earth itself is as well. Each day the surface of the Earth rises and falls about 30 centimeters, with the tides, yet you are moving with it so you would never notice it.

Pictures both taken from the Tides: Crash Course Astronomy #8 video.

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How Stonehenge is Astronomical

Posted on February 17, 2022 by Emily Bertram

Stonehenge is a prehistoric monument that is basically a ring of stones. Located in Salisbury, England, tourists come everyday to see the beautiful mystery. There are many legends and myths about how Stonehenge was created. According to different theories it could have been built by wizards, Danes or it was ruins from Roman Temples. Although these theories are entertaining to read about, the real reason why Stonehenge exists is because of astronomy. 

STONEHENGE

Stonehenge is astronomical because of where the rocks are placed. If someone were to sit in the center of the rocks, there is a perfect view of the summer solstice rising above the heel stone. According to The Guardian, it is believed that summer solstices have been celebrated at Stonehenge for thousands of years. I think that is very interesting and it raised some questions in my mind. For example, why the summer solstice? Are there any other reasons for Stonehenge? Who was the real creator of the structure? 

SUMMER SOLSTICE

I also find it interesting that there are many other structures similar to Stonehenge that are astronomical. For example, Nabta or Karnak in Egypt, Teotihuacan in Mexico, Moose Mountain in Saskatchewan, and many more. The Great Sphinx of Giza is also an astronomical clock. The dials point to the four constellations: Taurus, Leo, Scorpio and Aquarius. It tracks the stars as they orbit every 26,000 years. 

Have you ever been to an ancient astronomical structure? Leave a comment saying where you went!  

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Gravity in Solar System

Posted on February 17, 2022 by sissichen17
from Word Economic Forum

Acceleration due to gravity (g) is different for different planets due to their diverse masses and radii. Physicists usually figure out the by the formula g = GM/r**2, where G is the Universal Constant of Gravitation (6.67 * 10**(-11)), M is the mass of the planet, and r is the radius of the planet. By this calculation, the acceleration due to gravity, which is equivalent to gravitational strength, of all planets in our solar system is successfully figured out. Among all, Jupiter has the largest gravity as Jupiter is the largest planet within the Solar System, thus the largest mass. As mass is directly proportional to the acceleration due to gravity, Jupiter obviously has the largest g. Noticeably, as a gas giant, Jupiter does not have a true surface. Therefore, if people stepped on Jupiter, he/she will sink until reaching Jupiter’s solid core. The gravity of Jupiter is approximately 24.79m/s**2, which is 2.5 times the gravity of the Earth. In contrast, Mercury has the smallest g due to its small size, only 3.7m/s**2. Gravity runs the gamut in the Solar system, ranging from 3.7m/s**2 to 24.79m/s**2, which can be useful in space travel. For example, gravity assist maneuver can be especially useful in aerospace engineering to reduce expense and energy.

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Tides on Titan

Posted on February 17, 2022 by isaiandrade01
An artist’s depiction of a sea on Titan’s surface

As we learned in class, different celestial bodies can have varying tidal forces depending on their masses in relation to the object of interest. This phenomenon was mainly explored by the tidal forces on the Earth by the Moon and the Sun. In order to calculate the gravitational forces between two objects, we utilized the following equation for gravitational force:

F=G{\frac{m_1m_2}{r^2}}

As was concluded, the gravitational force exerted on Earth by the Sun was roughly 200 times stronger than that of the Moon on Earth. This was due solely to the massive size of the Sun in comparison to Earth even though it is much farther away from Earth than the Moon. Consequently, as a result of these two gravitational forces on Earth, we experience changes in the tides of our oceans along coasts around Earth.

The physics of tidal forces can also be applied to celestial bodies that are not Earth, specifically one of Saturn’s moons, Titan. Titan is the largest of Saturn’s 82 moons, and it’s been an object of interest for NASA’s Cassini probe. One of the most interesting facts about Titan is that, currently, it is the only other celestial body that has an Earth-like water cycle where liquid from its surface goes through similar steps such as evaporation from lakes and condensation from clouds. Not only does Saturn contain lakes of liquid ethane and methane on its surface, but because of the detected tidal forces due to Saturn, it is hypothesized that the top layer of water ice actually sits afloat a large subsurface ocean. This hypothesis was developed after the Cassini probe detected that the surface of Titan actually rises and falls 10 meters, given its location relative to Saturn. This rising and falling is quite clearly due to the gravitational force of Saturn which in comparison would be much more massive than Titan, also causing it to be tidally locked much like our Moon to Earth. This rising and falling of the surface is actually quite significant, for comparison Earth’s surface only moves about 0 to 4 inches depending on its location relative to the Moon and Sun. As a result, it’s very likely that underneath the top layer of water ice, there is a massive subsurface ocean that experiences massive gravitational forces, causing tides to significantly change the altitude of the entire top ice layer. It’s quite interesting to observe how there are common phenomena within the solar system, yet they can have much greater effects in some cases.

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Black holes and spacetime | blog post II

Posted on February 16, 2022 by clviggiano

Black holes are areas in spacetime where the gravitational force is so strong that nothing can escape. This includes forms of electromagnetic radiation like light. Current general relativistic models depict black holes as a taking on spheroid shapes, with an interminably long “tail” leading to its point of singularity. Singularity is a geometric point where any amount of mass is compressed into an infinitesimal density. This point has no volume; envision dropping a pen a piece of paper so that barely a dot shows up. Singularity is incalculably smaller than this dot. Surrounding every black hole is its event horizon, which is the area in which the escape velocity is equal to the speed of light. The breath of black holes’ event horizons do change based on the size and mass of their parent stars. Larger parent stars create larger (more distally expansive across spacetime) event horizons. Regardless of the event horizon, the escape velocity is the same. What changes is the distance at which the effects of the black hole cease to be felt; think about this also as the radius of the boundary at which nothing can ever escape. In 1971, Stephen Hawking proposed that the event horizon of a black hole should never shrink, a rule recognized as Hawking’s Area Theorem. This has become one of the most important laws in understanding black hole mechanics. A report published by MIT in July 2021 confirms this principle observationally—for the first time ever, some fifty years after it was introduced.  

Magnetic fields surrounding a black hole located at the center of galaxy Messier 87; first ever image of its kind. NPR/Event Horizon Telescope.
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Archeoastronomy: the Ancient Greeks

Posted on February 16, 2022 by Lindsey
Ancient Greek Calculations on Relative Sizes of the Moon, Sun, and Earth

The quest for knowledge about the universe we live in is not a modern phenomenon. Many cultures throughout history have devoted a significant amount of time and resources in pursuit of this knowledge. One ancient civilization that dramatically improved our knowledge of astronomy was the ancient Greeks.

One of the main goals of Greek astronomers was to determine an accurate geometrical model for celestial occurrences. One model was the Eudoxan model (created by Eudoxus of Cnidus, 410 – 347 BC), which presented the universe as a two-sphere model in which Earth was the stationary center with a larger sphere (termed the “heavenly realm”) centered around it that included all other celestial bodies (such as stars and planets). Using this model, Eudoxan was able to relatively accurately predict where and when planets would appear in the night sky. While his model was quite inaccurate, his attempts to geometrically model the world around us provided one of the earliest accounts of predicting planetary motion.

Another ancient Greek astronomer was Hipparchus (190-120 BC). He is most famous for his lunar theories. He used eclipses that occurred during his time to make conclusions about the period of the moon’s orbit. He also was one of the first people who recorded information about an apparent parallax of the moon and determined a somewhat accurate estimation for the summer solstice. Because of all of this and more, many consider him one of the best observational astronomers of all time.

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