Tag Archives: physics

A warp in the TimeSpace continuum!

Einstein also theorized that really big objects, like planets, warp the TimeSpace continuum around them. The example often used to illustrate this idea is a bowling ball on a trampoline. The bowling ball is so heavy that it makes a big downward bulge in the surface. Then you roll a marble around the edge of the trampoline. The marble feels a pull toward the bowling ball as it circles around the trampoline. A huge object like the Sun is so enormous that it bends TimeSpace around it. Like the marble, planets are pulled toward the Sun as they circle around. Don’t worry—the planets don’t go crashing into the Sun! Why not? Because they’re set in their orbits around it. There’s a balance between the Sun’s gravity (pulling Earth closer) and the Earth’s centrifugal energy (pulling Earth away) as she orbits. This situation has existed for billions of years.

Here’s an animation of the solar system traveling through space: https://www.youtube.com/watch?v=zBlAGGzup48

Here are some cartoons.


This one’s a guy drawing on a white board in time-lapse video which I kind of like—https://www.youtube.com/watch?v=awMw0Vv0QBA

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It’s time for Einstein’s General Theory of Relativity!

It seems Time and Space aren’t two separate things after all. They’re 2 parts of one thing: TimeSpace. They’re what’s called a continuum.
1 : a coherent whole characterized as a collection, sequence, or progression of values or elements varying by minute degrees

The Sweet-Salty continuum

I suppose a piano keyboard could be considered a continuum: lowest note on one end and highest note on the other, with the keys in between playing both low and high. You could draw up a continuum of food—from, say, the sweetest food you ever ate to the saltiest food you ever ate. Where is barbecue—both sweet and salty—on your continuum?

The continuum of TimeSpace has extreme ends, too—one end nothing but time and the other end nothing but space. This is really hard to think about. Time passes on one end but nothing physical is there. There’s physical stuff on the other end but nothing moves because it’s outside the medium of time. We live in the middle. We’re physical beings in a physical world who walk around and grow older and have kids and live our lives while plants sprout, bloom and die and the planets and stars whirl around in space.

(Does any of this remind you of Sunday-school? I mean how the Bible starts: “In the beginning…” and then God creates the universe, the Earth and the heavens, separates day from night. It’s how the Bible explains time and space. Which means God exists outside the TimeSpace continuum, which is too much for my brain to handle.)

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Physicists disagree


Getting back to our satellites—traveling around Earth at 17,000 miles per hour, a satellite’s time slows down, according to Einstein. Also according to Einstein, since gravity is weaker up where the satellites are, time moves a little faster. If that’s the case, wouldn’t a satellite’s GPS signal be inaccurate?

As I researched this question online, I got 2 answers to it: yes and no.

Yes. The satellites’ times slow down, but those amazing scientists who put the satellites up there in the first place cleverly adjusted their signals to compensate for it. Each satellite carries an atomic clock and sends a time & location signal at the speed of light, slightly adjusted (through programmed computer chips) for Einstein’s Special Theory. The clock takes into consideration both the slowing down because of speed and the speeding up because of weak gravity.


No. The satellites’ times slow down, but since they’re all zooming along at 17,000 miles per hour, all their times will be slowed down by the same ratio. So, it doesn’t matter. If all the satellites’ times agree with each other, the GPS system will be accurate. Or, the slowing down is cancelled out by the speeding up caused by weak gravity, so it’s what they call a ‘wash.’ Or, Einstein’s theories are a bunch of baloney so we shouldn’t pay any attention to them.
View at Medium.com

Um. I don’t know what to say here, gang. As you must be aware, I’m just some shmo who is learning as I write this. If you put me on the spot for which is the right answer, I’m going with the bloggers who have better proofreading/grammar skills and citations. If any of my loyal readers want to chime in, please do!

UPDATE: Regarding a satellite’s time difference because of relativity, our indefatigable physics consultant, Ms Physics, says:

Infinitesimal difference, yet a difference. You need to approach the speed of light 3.0 x 10^8 m/s (670,616,629 mph) to have a significant difference. Any way John you remember the precision of the Cesium clock, these differences would really become significant in GPSA calculation using General Relativity predicts that the clocks in each GPS satellite should get ahead of ground-based clocks by 45 microseconds per day.

A microsecond is one-millionth of a second. https://www.simetric.co.uk/si_time.htm

This is why I stick to drawing pictures and let others do the heavy brain-work.

I borrowed parts of this composition for my sketch. I removed the horses and put everybody in lab coats.

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Einstein’s Special Theory of Relativity

As you move faster, time slows down for you. Even though that’s true when you’re riding in a car, the slowdown is so teeny-tiny that it’s not worth measuring. But, if you were to travel to another galaxy at almost the speed of light, time would slow down—for you—to the point where you would age more slowly than your pals back on Earth.

When you got back from your trip, your friends would be old and wrinkly but you’d be ready to graduate from high school.

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Classical Relativity

Believe it or not, we’re coming to the end of The Western Civ User’s Guide to Time & Space. I would be cheating you customers if I didn’t spend a little time talking about TimeSpace.

The name Einstein has come to be shorthand for genius. It’s still difficult to imagine the abstract way he trained his brain to think about time and space. Back in 1905, Albert Einstein published his theories about Relativity. He had 2 theories, a Special and a General Theory. But first, let’s talk about Classical Relativity.

Classical Relativity: everything moves relative to everything else.

If you’re riding in a train going 45 miles per hour and throw a ball from the back of the car to the front, the ball seems to you to travel at 10 mph. To a cow standing in a field watching you throw the ball, the ball is traveling at 55 mph: 45 mph for the train plus 10 mph for the ball.

A speedometer can say we’re driving an automobile at 45 miles per hour, but that 45 mph is the car’s speed relative to the surface of good ol’ Planet Earth. Earth is also spinning around and circling the Sun. The Sun also circles around in the Milky Way, taking us along with him. The Milky Way circles around in the Universe. Even the Universe is moving—it’s expanding. How fast something is moving can only truly be measured as it relates to something else. That’s Classical Relativity.

I once tried talking my way out of a speeding ticket using this concept but the trooper wasn’t buying it. Just kidding! Actually, I started sobbing uncontrollably and he walked away in disgust.

UPDATE: My pal Ross sent this interesting article about how a fighter jet ran into its own bullets (the jet landed safely). It seems air-friction slowed the bullets but the jet’s engines allowed it to speed up. At any rate, probably I should redraw the above cartoon with the kid inside a box car, instead of standing on a flat car. https://arstechnica.com/tech-policy/2019/04/dutch-f-16-takes-cannon-fire-from-itself/?fbclid=IwAR1aIR4z2buoa-58GgXSQGUIlqAji6qFpE0MsXSAqC2gYGi6kUBg4UBYYLg

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Heliocentric blasphemy!

“We can’t torquemada heliocentrism; we can’t torquemada Copernicism; we can’t torquemada anything!”

We learned about how Aristotle and Ptolemy promoted the idea that the Earth is the center of the universe; she doesn’t move; all the planets and stars revolve around her. This is called geocentrism.

Copernicus had questions: if the planets and stars revolve around the Earth, howcome their orbits aren’t all perfect circles? He proposed that the Sun is the center of the universe and the planets and stars revolve around him. This is called heliocentrism.

When Galileo, with his newly-built telescope, observed moons revolving around Jupiter he could plainly see that not every heavenly body revolved around the Earth. Copernicus was right—at least Jupiter’s moons revolve around Jupiter. If Jupiter’s moons weren’t geocentric, how much else of the universe wasn’t geocentric?

This is the scientific method that is Galileo’s gift to us. He observed and asked questions and looked for proof.

Galileo was a brilliant self-promoter and made friends in high places. Nevertheless, his assertion that Aristotle was wrong got him in trouble with the Catholic Church. It’s not really clear to me what it was exactly that got him in hot water. Yes, there’s a passage in the Bible about the moon and Sun standing still (Joshua 10:13), but so what? The moon and Sun could still appear to stand still in a heliocentric universe.

It may be as simple as: Protestantism was still fresh; Christians were reading and interpreting the Bible for themselves (before moveable type only the priests had copies of the Bible); the Catholic Church’s establishment saw its power being challenged. Then Galileo came along and said everything you believe about God’s creation isn’t so. That may have been enough to cheese off the Church and put Galileo in front of the Inquisition.

Galileo did himself no favors when he published a fictional argument between 3 guys—to explain and prove his thesis—and made the guy with the pope’s point of view the moron. The upshot was heliocentrism was found to be heretical (against biblical belief) and Galileo was told never again to publish his heliocentric blasphemy. He was put under house arrest for the rest of his life.

It’s easy nowadays to paint the Church as the anti-science bad guy. This was indeed an embarrassing day for Christianity. If you look at the entire history of the Church, though, she’s done way more to encourage science and learning than to suppress it. Going back to Charlemagne, monasteries were the place you went to find books by classical thinkers, painstakingly translated into Latin by the monks. Most universities were originally Christian institutions. Anyhoo, a more recent pope finally admitted—after all these centuries—Galileo was right (thanks for linking this, Chuck Dillon!).


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Let me see what moons are like on Jupiter

The moons of Jupiter travel around her at a regular rate, like the hands of a clock. Galileo thought that you could use the moons as a universal clock. With that clock as a reference point, you could use local time to figure out where you are on Earth.

This sounds like a great idea, but how does it work? I’m guessing that you look at Jupiter, see where her moons are, and calculate where you are on Earth based on which moons you can see. For instance, on Wednesday, May 25, if you’re in North America and you have a telescope you can watch Io and Europa pass in front of Jupiter. If you live on the east coast you’ll see them only starting out; on the west coast you’ll see them only at the end. If you live in the middle of North America you’ll see most of the passage.

Since they know exactly when those moons will be zipping across the face of Jupiter and how long it will take, astronomers are able to make charts of the moons’ progress showing local times everywhere on Earth.

This strikes me as a huge amount of work to figure out where you are on Earth. Then again, I’m holding a cell phone with a GPS (Global Positioning System) so it’s pretty easy for me to know exactly where I am. If I were floating around in the ocean in the 1600s, with no GPS, I imagine I’d be pretty desperate to know exactly where I were and would consider breaking out the old telescope to have a squint at Jupiter and her moons.


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Moons of Jupiter

Galileo learned of a new invention called the telescope—it allows you to see things that are far away, things you can’t see with only your eyes. He’d never seen a telescope, but Galileo, that smarty-pants, figured out that it must be two magnifying lenses at either end of a tube. He built his own telescope and used it to look at the planets and stars. He discovered 4 moons orbiting the planet Jupiter: Io, Europa, Ganymede and Callisto.

When you or I discover moons orbiting around Jupiter, we say, “Neato!” or something and call it a day. If you’re Galileo, you think 2 thoughts: One, “Copernicus was right, everything in the universe doesn’t revolve around Earth!” and Two, “I can use those moons as a clock!”


What is Galileo’s Telescope?

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Guest Blogger: Ms Physics

Diana invited me to present to her students a few years ago—a fun bunch of kids!

I’ve been pals with Diana Eline since high school. She always had more brains than I do. Diana teaches high school physics. After chatting about Galileo, I asked her to contribute some thoughts to this blog. Diana was kind enough to call together an emergency meeting of the Physics Nerds Society. Here’s what she has to say:

Galileo Galilei was born in Pisa in 1564, the first of six children of Vincenzo Galilei, a musician and scholar. In 1581 he entered the University of Pisa at age 16 to study medicine, but was soon sidetracked by mathematics. He left without finishing his degree (yes, Galileo was a college dropout!). In 1583 he made his first important discovery, describing the rules that govern the motion of pendulums.

First of all, as I tell my students, that dude Aristotle screwed up science for a long time by saying all matter is composed of Earth, Water, Air or Fire. As Aristotle was such an acclaimed philosopher no one dared to disagree with him except Galileo. Aristotle also said that heavier objects fall faster to the earth than lighter objects. Which, we of course know that it is not true. In a vacuum all objects fall to the earth at an acceleration of 9.81 meters/second squared. Only due to air resistance (air is actually composed of matter—namely gas molecules—78% nitrogen and 21% oxygen) which slows down objects with a large surface-area-to-mass ratio. Galileo also discovered many stars in the Milky way. He invented the pendulum clock. He discovered Jupiter’s moons. Although he did not invent the telescope he was the first to use it systematically to observe celestial objects and record his discoveries. His book, Sidereus Nuncius or The Starry Messenger was first published in 1610 and made him famous.

Galileo thought that a ball, rolling or sliding down a hill without friction, would run up to the same height on an opposite hill. Galileo’s conclusion from this thought experiment was that no force is needed to keep an object moving with constant velocity, which led to Newton’s 3 Laws of Physics!

Galileo Galilei is considered the father of modern science and made major contributions to the fields of physics, astronomy, cosmology, mathematics and philosophy. His flair for self-promotion earned him powerful friends among Italy’s ruling elite and enemies among the Catholic Church’s leaders. Galileo’s advocacy of a heliocentric universe brought him before religious authorities in 1616 and again in 1633, when he was forced to recant and placed under house arrest for the rest of his life.

Long story short, my enthusiasm for Physics has led my oldest son to pursue a PhD in Astrophysics and continue as an underpaid scientist!

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