“We do not believe any group of men adequate enough or wise enough to operate without scrutiny or without criticism. We know that the only way to avoid error is to detect it, that the only way to detect it is to be free to inquire. We know that in secrecy error undetected will flourish and subvert.” –J. Robert Oppenheimer
THE SWAMP RUNS DEEP. Sometimes you cannot tell people the truth. You must show them. Only then, at the PRECIPICE, will people find the will to change [to participate]. We, the People, have been betrayed for a very long time. WILL YOU STAND? FOR GOD AND COUNTRY. FOR FREEDOM. FOR HUMANITY. WHERE WE GO ONE WE GO ALL !!! Q
Given the events of the week, both real and invented narratives, it’s a good time for a rally.
For those feeling the weight of the world given what we are seeing and hearing, here’s a reminder that we are America.
America really needs to save herself. We need a leader to remind us how.
Hopefully, the boss will lower some sort of boom tonight.
51 hours until President Trump's Save America Rally in Cullman Alabama. Already about 20 people camped out and waiting. #SaveAmericapic.twitter.com/5CAuzInS6C
Before European settlement, the area that today includes Cullman was originally in the territory of the Cherokee Nation. The region was traversed by a trail known as the Black Warrior’s Path, which led from the Tennessee River near the present location of Florence, Alabama, to a point on the Black Warrior River south of Cullman. This trail figured significantly in Cherokee history, and it featured prominently in the American Indian Wars prior to the establishment of the state of Alabama and the relocation of several American Indian tribes, including the Creek people westward along the Trail of Tears. During the Creek War in 1813, General Andrew Jackson of the U.S. Army dispatched a contingent of troops down the trail, one of which included the frontiersman Davy Crockett.[5]
In the 1820s and the 1830s, two toll roads were built linking the Tennessee Valley to present-day Birmingham. In 1822, Abraham Stout was given a charter by the Alabama Legislature to open and turnpike a road beginning from Gandy’s Cove in Morgan County to the ghost town of Baltimore on the Mulberry Fork near Colony. The road passed near present-day Vinemont through Cullman, Good Hope, and down the current Interstate 65 corridor to the Mulberry Fork. The road was later extended to Elyton (Birmingham) in 1827. It then became known as Stout’s Road. Mace Thomas Payne Brindley was given a charter in 1833 to turnpike two roads, one running between Blount Springs to Somerville by way of his homestead in present-day Simcoe, and the second road passing west of Hanceville and east of Downtown Cullman to join Stout’s Road north of the city. What later became the Brindley Turnpike became an extension of Stout’s Road to Decatur. Cullman later became located between the juncture of the two roads, and they predated the corridor of U.S. Route 31.
During the Civil War, the future location of Cullman was the site of the minor Battle of Day’s Gap. On April 30, 1863, Union forces under the command of Colonel Abel Streight won a victory over forces under Confederate General Nathan Bedford Forrest. This battle was part of a campaign and chase known collectively as Streight’s Raid. Although Streight got the upper hand in this battle, Forrest would have the last laugh. In one of the more humorous moments of the war, Streight sought a truce and negotiations with Forrest in present-day Cherokee County near present-day Gaylesville. Although Streight’s force was larger than Forrest’s, while the two were negotiating, Forrest had his troops march repeatedly in a circuitous route past the site of the talks. Thinking himself to be badly outnumbered, Streight surrendered to Forrest.[6]Colonel John G. Cullmann, founder of Cullman (1823–1895)
Cullman itself was founded in 1873 by Colonel John G. Cullmann, a German immigrant.[7] Cullmann had been an advocate of democratic reforms in his native Bavaria, having fought and acquired his honorific title “Colonel” during the Revolutions of 1848–49. After the failure of the revolution, Cullmann found himself in financial ruin. In the years to follow, he would try to re-establish himself in business, but after several setbacks, including a great financial loss in the First Schleswig War, he would remain unsuccessful. As time went on and Prussia, under King Wilhelm I and his Minister President Otto von Bismarck, began to exert more influence in the German region (eventually unifying Germany under Prussian rule in 1871), Cullmann began to believe that his political ideals were fundamentally incompatible with those of the German Government. As a result, he decided to emigrate from his homeland. Settling first in London due to fears that he would be forced to join in the ongoing American Civil War, Cullman eventually came to America in 1865. He moved to Alabama in 1871 and, in 1873, negotiated an agreement to act as agent for a tract of land 349,000 acres (1,410 km2) in size, owned by the Louisville and Nashville Railroad Company, on which he established a colony for German immigrants.[8][9]
Five German families moved to the area in March 1873; in 1874, the town was incorporated and named after Colonel Cullmann (with the town name being Americanized to ‘Cullman’ with one ‘n’). Over the next 20 years, Cullmann encouraged around 100,000 Germans to immigrate to the United States, with many settling in the Cullman area. Cullmann drew on his military engineering training in laying out and planning the town. During this period, Cullman underwent considerable growth. German continued to be widely spoken, and Cullmann himself was the publisher of a German-language newspaper. When Cullmann died in 1895, at the age of 72, his funeral was marked by the attendance of Governor William C. Oates.[8] The site Cullmann selected for his headquarters is now his gravesite.
German immigrants also founded St. Bernard’s Monastery, on the grounds of which is the Ave Maria Grotto, containing 125 miniature reproductions of some of the most famous religious structures of the world. It is Cullman’s principal tourist attraction.[10]
During the 1890s, and still to this day, Cullman was reported to be a sundown town, where African Americans were not allowed to live.[11][12][13] The Ku Klux Klan would maintain a presence in the county throughout the civil rights movement, erecting signs that deterred African Americans from being within the county at night. This subsequently led to a rise in population of Colony, Alabama which was a safe haven for the discriminated.
For many years Cullman was a college town, with Saint Bernard College serving as the home of several hundred students. In the mid-1970s, St. Bernard briefly merged with Sacred Heart College (a two-year Benedictine women’s college), to become Southern Benedictine College. That college closed in 1979, and it now operates as St. Bernard Preparatory School. The former site of Sacred Heart College is now the Sacred Heart Monastery, which serves as a retreat center operated by the Benedictine Sisters of Sacred Heart Monastery.[14]
During the 20th century, Cullman developed a more diverse economy, including several manufacturing and distribution facilities. The City of Cullman regularly ranks as a top ‘micropolitan’ city in the nation.[15]
Cullman gained national attention in early 2008, when a special election was held to fill a vacancy in the Alabama House of Representatives. The district that included Cullman elected James C. Fields, an African-American, in that special election.[16]
Cullman’s German heritage was repressed during World War I and World War II, while the United States was fighting Germany. This was reversed in the 1970s, with renewed interest in the city’s history and heritage. Today, Cullman holds an annual Oktoberfest.[17] An honorary “Bürgermeister” is elected for each Oktoberfest. For many years the Oktoberfest did not include alcohol because Cullman was dry, but starting in 2011 the Oktoberfest was able to offer beer.[18]2011 tornado damage
Downtown was significantly damaged by an EF4 tornado during the 2011 Super Outbreak. Hitting on April 27, it destroyed many buildings in downtown and in an east-side residential area, but causing no fatalities. The twister moved northeast towards Arab and Guntersville, killing two Cullman County residents and at least four others.[19] Cullman has since rebuilt and revitalized the downtown area. New zoning laws and alcohol ordinances have allowed for greater expansion and growth in the downtown Cullman area.[15]
Over the past four years, President Donald Trump’s administration delivered for Americans of all backgrounds like never before. Save America is about building on those accomplishments, supporting the brave conservatives who will define the future of the America First Movement, the future of our party, and the future of our beloved country. Save America is also about ensuring that we always keep America First, in our foreign and domestic policy. We take pride in our country, we teach the truth about our history, we celebrate our rich heritage and national traditions, and of course, we respect our great American Flag.
We are committed to defending innocent life and to upholding the Judeo-Christian values of our founding.
We believe in the promise of the Declaration of Independence, that we are all made EQUAL by our Creator, and that must all be TREATED equal under the law.
We know that our rights do not come from government, they come from God, and no earthly force can ever take those rights away. That includes the right to religious liberty and the right to Keep and Bear Arms.
We believe in rebuilding our previously depleted military and ending the endless wars our failed politicians of the past got us into for decades.
We embrace free thought, we welcome robust debate, and we are not afraid to stand up to the oppressive dictates of political correctness.
We know that the rule of law is the ultimate safeguard of our freedoms, and we affirm that the Constitution means exactly what it says AS WRITTEN.
We support fair trade, low taxes, and fewer job-killing regulations, and we know that America must always have the most powerful military on the face of the Earth.
We believe in Law and Order, and we believe that the men and women of law enforcement are HEROES who deserve our absolute support.
We believe in FREE SPEECH and Fair Elections. We must ensure fair, honest, transparent, and secure elections going forward – where every LEGAL VOTE counts.
Plans at this time are that I will be away from the keyboard when the rally happens, so please keep the thread lively. I’ll put some links here for better viewing as the day goes on and they become available.
Joe Biteme, properly styled His Fraudulency, continues to infest the White House, we haven’t heard much from the person who should have been declared the victor, and hopium is still being dispensed even as our military appears to have joined the political establishment in knuckling under to the fraud.
One can hope that all is not as it seems.
I’d love to feast on that crow.
Justice Must Be Done.
The prior election must be acknowledged as fraudulent, and steps must be taken to prosecute the fraudsters and restore integrity to the system.
Nothing else matters at this point. Talking about trying again in 2022 or 2024 is hopeless otherwise. Which is not to say one must never talk about this, but rather that one must account for this in ones planning; if fixing the fraud is not part of the plan, you have no plan.
Lawyer Appeasement Section
OK now for the fine print.
This is the WQTH Daily Thread. You know the drill. There’s no Poltical correctness, but civility is a requirement. There are Important Guidelines, here, with an addendum on 20191110.
We have a new board – called The U Tree – where people can take each other to the woodshed without fear of censorship or moderation.
And remember Wheatie’s Rules:
1. No food fights 2. No running with scissors. 3. If you bring snacks, bring enough for everyone. 4. Zeroth rule of gun safety: Don’t let the government get your guns. 5. Rule one of gun safety: The gun is always loaded. 5a. If you actually want the gun to be loaded, like because you’re checking out a bump in the night, then it’s empty. 6. Rule two of gun safety: Never point the gun at anything you’re not willing to destroy. 7. Rule three: Keep your finger off the trigger until ready to fire. 8. Rule the fourth: Be sure of your target and what is behind it.
Gold has actually moved around a bit, but the end result was a tiny gain over the week. Silver has dropped significantly (about 3 percent by eyeball). Platinum was well under a thousand yesterday, and has recovered…some. Palladium is down over ten percent. And Rhodium is getting its ass kicked; it dropped 1900 dollars on Friday alone.
From Special to General
Introduction
Let us start off by recapping our list of “as of 1894” mysteries and conservation laws, and bring things up to date including the Bohr atom and the work done on justifying the periodic table (much of which happened well beyond 1913). Otherwise, we’re at about 1913 now.
Let’s recap/update those lists.
Conservation of mass
Conservation of momentum
Conservation of energy
Conservation of electric charge
Conservation of angular momentum
(ADD:) Conservation of mass-energy
The following mysteries were unanswered at the end of 1894.
Why was the long axis of Mercury’s orbit precessing more than expected, by 43 arcseconds every century? Was it, indeed, a planet even closer to the sun? If so, it’d have been nice to actually see it.
Why was Michelson unable to measure any difference in speed of light despite the fact we, being on planet Earth that is orbiting the sun, had to be moving through the medium in which it propagates?
What makes the sun (and other stars) shine (beyond the obvious “they shine because they’re hot” answer). What keeps the sun hot, what energy is it harnessing?
How did the solar system form? Any answer to this must account for how the planets, only a tiny fraction of the mass of the solar system, ended up with the vast majority of the angular momentum in the system.
What is the electrical “fluid” that moves around when there is an electric current, and that somehow seems imbalanced when we perceive that an object has a charge? Were there both negative and positive fluids, or just one fluid that had a natural neutral level; below it was negative (deficit), above it was positive (excess)?
Why are there so many different kinds of atoms? How did electrical charges relate to chemistry? How is it that 94 thousand coulombs of charge are needed to bust apart certain molecules (though it often had to be delivered at different voltages depending on the molecule)?
Why were the atomic weights almost always a multiple of hydrogen’s? Why was it never quite a perfect multiple? Why was it sometimes nowhere near to being a multiple?
Why does the photoelectric effect work the way it does, where it depends on the frequency of the light hitting the object, not the intensity?
Why does black body radiation have a “hump” in its frequency graph?
In just 20 years we had come a long way. Out of nine mysteries, only three were completely left open, and another was mostly solved. And even mystery number 3 had tantalizing hints.
More Developments in Special Relativity
A few weeks ago–actually the last time I used this particular eagle–I described the four Big Papers Einstein published in 1905. Two of them had to do with what today we call “Special Relativity.”
What made it “special”? Did it ride the short bus to school?
What made it special was that it only applied to a very specific case, the case where the frames of reference are not accelerating. Constant speed, even high speed, isn’t an issue, but if there’s any sort of acceleration, it’s a different ball game.
General relativity doesn’t have this restriction. Special relativity turns out to be a special case of general relativity.
1915 was the year Einstein first put forward general relativity, which means that historically speaking, with the last article taking us up to that about then dealing with subatomic physics, this is the right time to take up general relativity.
But there had been some developments in special relativity in the meantime. Einstein hadn’t really thought about relativity from a geometric point of view, but many others, including his former math professor Hermann Minkowski, did. They pointed out that if you simply consider time as being a fourth dimension, a lot of things fell into place.
This does make some sense. After all, if you and I agree to meet at the corner of Pikes Peak and Cascade on the 14th floor of the Holly Sugar Building (which isn’t called that any more), we’ve specified a meeting place in three dimensions…latitude, longitude (the streets run north/south east/west in that part of town), and elevation (14th floor). Or coordinates…a triplet of them…can be used to define any location in space once you’ve defined the coordinate system (and it doesn’t even have to be a cubical grid either; cylindrical or spherical coordinates can work). You need three coordinates, though, because space is three dimensional. You can get by with two if you implicitly specify the third (in this case, surface level could be assumed; that’s probably a good idea when dealing with ships).
But if you and I arrange a meeting place in this manner, we’re committing a Bidenesque screwup: Because we also need to specify a time. So really, you need four coordinates, three space coordinates x, y, and z, and a time coordinate, t.
When you specify all four, you’ve defined what physicists call an event. And you’re doing it in terms of spacetime.
And so, it turns out that special relativity fits well with the concept of spacetime and works in four dimensions. This was pointed out by Minkowski.
But there was a difference! And it becomes most manifest when considering interval. The interval is the distance between two events.
If you are using a “Cartesian” (cubic grid) coordinate system, the difference between two points in space is an extension of Pythagoras. In two dimensions, on a Cartesian grid, the distance between two points is simply the difference between their x-coordinates, squared, plus the difference between their y coordinates, squared, then take the square root of all that.
It’s precisely equivalent to a2+b2=c2. (And note, it doesn’t make any difference whether you subtract point 1 from point 2, or vice versa. Sure, you will get opposite signs depending on the order, but those get wiped out when you square the differences.)
To move up to three dimensions, you can square the two dimensional distance again, then square the difference in the third coordinate. But when you do that, it’s algebraically equivalent to just squaring all three differences, adding them together, then taking the square root:
First there’s one issue to clear out of the way: time is measured in seconds and distance is measured in meters; by simply taking a difference in time and jumbling it in with three differences in meters, you are mixing apples and roadcones.
It turns out that with spacetime, a distance of d = ct is equivalent to a duration of t. In other words a one second time difference is equivalent to a distance of 299,792,458 meters. So when doing this computation, if you divide your space distances by the speed of light, you get units of seconds, and now the four “pieces” of the equation all match units. You’ll have to multiply the result by c again to get back to meters.
So let’s imagine two events at the same x and y, but with z differing by 299,792.458 meters, and t differing by one second. Dividing all of the space coordinates by c, you get the x and y differences = 0, the z difference being 1 second, and of course the t difference is 1 second.
Incidentally a difference is often denoted by Δ, the Greek letter delta, so we can say Δx=0, Δy=0, Δz=1, and Δt=1. It’s a lot more convenient, and amongst techie types “delta” is often slang for “change” or “difference.” (“What’s the delta in the cost of gas switching from the orange guy with the mean tweets to His Fraudulency?” for instance.)
So square everything and get 0, 0, 1, 1, add them together to get 2, take the square root, and the interval is 1.414 seconds, or about 424 million meters, right?
Well, no. The BIG difference is that with space time you subtract the space components from the time component!
Note that the time difference is first and all the space differences are subtracted from it.
So in this case the interval is zero seconds; the two ones cancel.
(Equivalently, you could multiply the time by c and work entirely in meters, rather than seconds…but that would have made the arithmetic ugly.)
Now there’s only one thing that can get from that first event, to that second event. The one thing that can move 299,792,458 meters in one second, and that, of course, is light in a vacuum.
But the light, in doing so, covers no interval. Which means that the light beam perceives no distance traveled and no time elapsed! But if you remember the time and distance dilation formulas from the last time we talked about special relativity, that’s what we would expect. At light speed, both effects cause the elapsed time and traveled distance (from the point of view of the light beam) to reach zero.
So what we have here is a geometric model of special relativity.
OK, let’s play another game here. Let’s make the space distance twice as much as it was before, while leaving the time distance 1. You end up with Δx=0, Δy=0, Δz=2, Δt=1.
Plugging that in, we get sqrt( 12 – 02 – 02 – 22 ) = sqrt( 1 – 4 ) = sqrt( -3 ).
Now you can’t take the square root of -3 and get a meaningful distance (or time) out of it. What the spacetime model is telling you is you cannot get from one event to the other. If you could, it would be by traveling faster than the speed of light. So the spacetime model has built into it a rationale for not being able to exceed the speed of light in a vacuum.
Einstein didn’t use this in 1905, but he adopted it shortly thereafter. (I wonder if Minkowski ever told his former student how proud he was of him.)
Minkowski invented the spacetime diagram, where the vertical axis is time, and the horizontal axis is space. Objects traveling on this diagram cannot do so at a slant of less than 45 degrees (that implies traveling faster than c), light itself moves at a 45 degree slant on the diagrams.
An interesting consequence of spacetime is that everything moves at exactly the same speed through it. You, sitting in your chair reading this are traveling through time purely, at one second every second. Move fast enough, and your motion becomes predominantly through space and you are moving slower through time. The second motion is called spacelike because most of the motion is through space, and time slows down signficantly, the first motion is called timelike not because it’d be snarky to refer to it as “sitting on your ass” but because most of the motion is along the time axis.
More Einsteinian Thought Experiments
Spacetime, it turns out, is the easiest way of dealing with general relativity. Not that it’s easy.
I actually wasn’t that far off when I talked about special relativity riding the short bus. The math involved with it is an absolute breeze compared with the math in general relativity. It’s a major event when someone is able to solve the general relativity equation for a certain specific scenario. In fact, I will be honest with you: I don’t understand the math. I never got exposed to tensors; I just have a vague idea that they’re sort of like matrices (which are a power tool in mathematics I do know something about), but not quite.
So with that, I can’t comprehend the real situation then try to explain it to you. I have to rely on the same science-for-senators handwaving that you’ve probably already seen. As such, I’ve been half-dreading writing this post.
But, it does start with Einstein’s doing thought experiments, so at least that part should be comprehensible if I am doing my job right. [Only later will you see the wild leap I can’t justify.]
The supposition this time is that if you were in a locked chamber, no way to see in or out, and were feeling earth-normal gravity, you’d be unable to distinguish it from being in a room that is being accelerated ‘upward’ at g, the acceleration due to gravity. The rules of physics would be the same; any experiment you could carry out would have the same result.
That doesn’t seem too unreasonable. If you drop your four hundred ounce gold brick on your foot in either scenario, it will hurt just as much, just as quickly.
But this does lead to differences with the conventional understanding when you deal with light.
The conventional understanding is that light has no mass, so gravity should not act on it. A beam off your laser pointer should travel in a straight line no matter how strong the gravity is.
On the other hand, if you’re in a room that’s under acceleration, it feels like gravity, there’s an obvious up and a down. But you should be able to tell the difference between an accelerating room and one experiencing gravity, because if you fire your laser pointer horizontally, and the room is accelerating, you should see the beam bend. That is because the beam of light is moving vertically at the same speed you are, but once it has left the laser pointer, it doesn’t speed up in the vertical direction, but you and the room do, so you see the beam drop.
So if the room is feeling gravity, the beam shouldn’t bend because the force of gravity on a massless object should be zero, but if the room is being accelerated, the beam should bend, because the room is moving faster than it was before, by the time the beam hits the wall.
On the left, the light source (and you) are moving at the same speed as the rocket. Middle diagram, but the rocket is speeding up, it’s pulling ahead, so you see it higher. The beam of light, though, can’t speed up in the vertical direction so it seems to trace a curve inside the rocket. Finally it hits the far wall of the rocket. From inside the rocket, the beam appears to have dropped due to gravity.
But if Einstein is right and there really is no way to tell the difference, then either both beams need to move in a straight line, or both beams need to bend. In the second case, light is affected by gravity even though it has no mass.
You need really strong gravity to see this, though. Or a long distance. Because light crosses any normal everyday distance in microseconds or even nanoseconds, and if it’s going to “drop” due to gravity, well, gravity only gets to act on it for a few billionths of a second. Plug that in to d=1/2at2 and it’s almost nothing.
OK, but there is a concrete prediction. A light beam going by a massive object, should bend a bit. This is testable with great difficulty.
Here’s another: If light is affected by gravity, light traveling upward has to lose energy, just like a thrown baseball loses kinetic energy (trading it for potential energy) and slowing down. But light cannot lose energy by slowing down, its speed in any particular medium is a constant.
It can lose energy another way, however. Remember E = hv? (Where ν is the frequency?)
So the light, climbing in a gravity field, should decrease in frequency. That’s the only way it can lose energy. Similarly, light going “downhill” should increase in frequency to gain energy.
There’s an alternative way of looking at this though. Imagine that light beam in the accelerating room, firing upward from the floor. By the time the beam reaches the ceiling, the ceiling has sped up, so there’s a doppler shift in the wavelength, towards the red. Since you can’t tell this case from a room feeling “real” gravity, in that room the light has to redshift too.
This is gravitational red shift. Visible light becomes redder as it moves uphill. Again, this effect is tiny on Earth, but it’s measurable today (I don’t think it was measurable using 1915 equipment).
Hiding inside that effect is another.
Imagine someone on the surface of earth, shining a light straight up. He blinks, and then a second later he blinks again. In the meantime, about 600 trillion wavelengths of the light are emitted.
Someone, up in space, will see the same sequence of events. Blink, 600 trillion wavelengths, then a blink. But the light is red shifted when he sees it. 600 trillion wavelengths takes more than a second to pass by him, because the frequency has dropped.
Therefore he sees it take more than a second between the two blinks. From his point of view, time is running slower down on earth than it is for him in space.
This is gravitational time dilation.
So these are concrete, comprehensible predictions to see whether an accelerating reference frame, where effects happen due to inertia, is truly the same as one with gravity (effects due to mass).
But when Einstein followed the math…it got interesting. And I’m going to have to state it without trying to justify it. Sorry. Complicated business!
Gravity, it turns out, isn’t a “force” like electromagnetism is. It turns out that any object not being accelerated by a real force (like a rocket motor), travels a straight line in space time, the shortest distance between two events. If you think it’s curving because, for instance it’s a space probe doing a “flyby” of Jupiter, it’s because spacetime is curved.
OK, now this takes time to wrap one’s brain around, and if you fail at it you’re in very good company. How does space itself actually bend? Objects bend in space, space itself, can’t bend, there’s nothing to bend.
Nevertheless it does. Not just in Einstein’s thought experiments, but in reality.
Einstein used his new concepts to compute the orbit of Mercury.
Remember there had been a long-standing mystery about Mercury. It orbits the sun in a markedly elliptical orbit, and under Newtonian two-body gravity, the long (or “major”) axis of the ellipse should never change direction. But in fact it does change direction. Some of this can be shown to be due to the other planets’ pulling on Mercury constantly. But not all. After subtracting all of that out, the major axis still shifts by 43 arc seconds every century. That’s an angle about three quarters the width of a quarter set out at a hundred yards, and it takes a century (about 400 revolutions of Mercury about the sun) for it to make that shift.
Precession of Mercury’s orbit. This is empahtically not to scale. Even 4000 orbits wouldn’t show a shift visible at this size.
People had theorized that an undiscovered planet closer to the Sun than Mercury could be perturbing Mercury’s orbit, but it would be frustratingly difficult to see such a planet so close to the Sun.
But when Einstein did the computation with his modified law of gravity, he found that an object orbiting that close to a very massive object like the sun…would see a shift of exactly this amount!
The net effect of Einstein’s new law of gravity is that near very massive objects, gravity’s effect is slightly greater than an inverse square law. Which means that at perihelion (closest approach) gravity is a bit stronger than Newton would expect. However, Kepler’s second law still applies (a line from the sun to the planet sweeping out equal areas in equal times) because it depends on the conservation of angular momentum. So this manifests itself as the elliptical orbit behaving like something out of a Spirograph set.
OK, so Einstein had made one prediction he could test himself. But to be really solid science, predicting new phenomena (rather than just being a possible explanation of a known phenomenon) would be good.
Testing General Relativity
The light bending, doppler effect, and time dilation effects were something that had not been seen before, had not been predicted by any other theory, and if seen would be otherwise unexpected; i.e., a successful prediction by this theory…three successful predictions, actually.
As it turned out, the light bending was the easiest. For this you can use a large massive body that’s between you and stuff of known position, if the position of those background objects appears shifted near the body, you have gravity (from the massive body) bending the light coming to you from the background objects.
This is a job for the Sun. As seen from earth, it moves against the background (it’s really the Earth moving), which is a known pattern of stars. We’ve got plenty of star maps taken when the sun is nowhere along the line of sight (in fact when the sun is behind the mapper, because he’s doing this at night and the sun is below his feet somewhere). So we just need to see if the stars seem shifted (away from the sun as it turns out) when the sun is on the line of sight to the stars.
Did I mention earlier the sun is bright? This makes it impossible to see stars that are almost behind it.
Except during a solar eclipse, when the moon neatly covers the sun!
There was a solar eclipse in 1919. Astronomer Arthur Eddington took photographs, not of the corona (as people usually do during eclipses) but of the stars near the Sun. The elegant mathematical reasoning of Albert Einstein was put to the test. (If you don’t find it elegant, it’s because you haven’t seen and understood the math; I haven’t understood it myself, so I’m taking other peoples’ word for it that its elegant.)
It was hard to measure accurately enough to truly nail it down, but the stars’ apparent position had indeed shifted and the measured effect was consistent with General Relativity.
This was big news. I mean, really big news. It made the newspapers read by regular people. This was when Einstein became famous outside of scientific circles.
Today, we can see entire galaxies bending the light of galaxies behind them. In fact, there’s a spectacular instance of two almost-perfectly-lined up galaxies causing the background galaxy to look like a ring, known as an Einstein Ring:
The blue arc, almost a complete ring, is a background galaxy distorted by the gravity of the yellowish orange elliptical galaxy in front of it.
The gravitational redshift took longer. For this, the ideal situation is a bright, massive, small object (small is better because the gravity is more intense, and a white dwarf, which is a sun-sized star that has run out of nuclear fuel and collapsed down to the size of the earth, is ideal. It still shines brightly because it will take millions or even billions of years to cool off, but it has a very strong gravitational field. As early as 1925, someone attempted to measure the gravitational redshift off of the star Sirius B (see my article on Sirius A and B: https://www.theqtree.com/2020/01/01/another-sirius-tale-of-two-stars/), but other scientists pointed out there was too much glare from Sirius A (which is, after all the brightest star in the nighttime sky). Finally in 1954 Popper got a good measurement off of 40 Eridani B and confirmed this prediction. It’s also possible now to measure the shift in frequency of gamma rays going up several stories here on Earth.
The gravitational time dilation can be measured by two different atomic clocks at different elevations. Eventually, the lower one will fall behind the upper one.
Most famously, the GPS constellation of satellites demonstrates both special relativity time dilation, and general relativity time dilation.
The GPS system works by having each satellite sending out time signals. Their position at any time can be computed by your GPS receiver, so it’s just a matter of comparing the signals from at least four (but even more is better), noticing the differences of the times in the signals, turning that into different distances from the satellites, then doing a lot of geometry to triangulate, and figure out where the receiver must be.
Extremely accurate time sources on the satellites are an absolute necessity. If one is off by ten nanoseconds, your position will be off by ten feet (light travels roughly a foot per nanosecond).
The satellites are moving quickly, which means a clock on that satellite will seem, from down here on earth, to be ticking more slowly due to special relativity time dilation. (Not much more slowly, but enough to be measurable with modern atomic clocks.) They are also higher so due to gravitational time dilation, our clocks should run more slowly than the GPS satellite ones. The two effects are in opposite directions, so they will tend to cancel each other out. The gravitational effect is the larger of the two, so from our standpoint the GPS clocks look like they’re running faster than they would to someone actually on one of the satellites. In fact, it will run 38 microseconds per day faster than you’d expect without either time dilation effect. That would be enough to throw position calculations off by several miles…after one day.
This effect is real, it does happen. What the GPS engineers do is slow the satellites’ clocks down to compensate. That way in orbit when they speed up (as seen by us), we see the clocks ticking off normal seconds, and so if you drive your car into the Mississippi river when trying to get to Pikes Peak, it’s not the fault of GPS.
GPS wasn’t designed for the purpose of testing general relativity, but there are a couple of rather more detailed predictions involving a phenomenon called “frame dragging” (which I am not even going to try to explain, because I want to publish this this week, not sometime in October) that have been confirmed by satellites deliberately launched to test general relativity.
General relativity has met every test thrown at it. It’s real. Spacetime bends. And objects move along the shortest possible path through spacetime.
As famously put by John Archibald Wheeler (1911-2008, a veteran of the Manhattan Project) in 2000, “Spacetime tells matter how to move; matter tells spacetime how to curve.”
I debated whether to put a “rubber sheet” diagram in this post. They’re very problematic. Yes, you can see how an object might follow a curved path on the rubber sheet, which is supposed to be how gravity works, but the rubber sheet is itself bent by gravity pulling on an object. If you can’t ignore that, you’re going to be hung up on the fact that (demoed) “gravity” is caused by (real) gravity. I decided, ultimately, not to do it even though I could write disclaimer after disclaimer that it’s a visualization tool only, not an explanatory one. (And I believe I hear Wolf breathing a sigh of relief.)
But one doesn’t need a rubber sheet diagram to know that Joe Biden didn’t win.
And, in case you didn’t notice…we can cross mystery number one off the list. Thanks, Herr Doktor Einstein!
Obligatory PSAs and Reminders
China is Lower than Whale Shit
Remember Hong Kong!!!
Whoever ends up in the cell next to his, tell him I said “Hi.”
中国是个混蛋 !!! Zhōngguò shì gè hùndàn !!! China is asshoe !!!
China is in the White House
Since Wednesday, January 20 at Noon EST, the bought-and-paid for His Fraudulency Joseph Biden has been in the White House. It’s as good as having China in the Oval Office.
Joe Biden is Asshoe
China is in the White House, because Joe Biden is in the White House, and Joe Biden is identically equal to China. China is Asshoe. Therefore, Joe Biden is Asshoe.
But of course the much more important thing to realize:
Joe Biden Didn’t Win
乔*拜登没赢 !!! Qiáo Bài dēng méi yíng !!! Joe Biden didn’t win !!!