The Greatest Mistake In The History Of Physics

The Greatest Mistake In The History Of Physics

“Poisson attempted to disprove Fresnel’s theory by showing that it led to a logical fallacy: reductio ad absurdum. Poisson’s idea was to derive a prediction made by the light-as-a-wave theory that would have such an absurd consequence that it must be false. If the prediction was absurd, the wave theory of light must be false. Newton was right; Fresnel was wrong. Case closed.

Except, that itself is the greatest mistake in the history of physics! You cannot draw a conclusion, no matter how obvious it seems, without performing the crucial experiment. Physics is not decided by elegance, by beauty, by the straightforwardness of arguments, or by debate. It is settled by appealing to nature itself, and that means performing the relevant experiment.”

It’s now been 200 years since one of the most embarrassing moments in the history of physics. The famed scientist Simeon Poisson, at a conference on the nature of light, discounted one of the entrant’s theories because its predictions were completely absurd. He attempted to have the contestant, a young civil engineer named Fresnel, laughed out of the competition because his theory predicted that, at the center of a shadow, a bright spot of light should appear. Yet Poisson made these moves without ever performing the experiment that would decide whether Fresnel was right or wrong!

You can’t do that in science, no matter how sure you are that you know what is or isn’t absurd. Nature must decide. And that, in science, is always the lesson.

What Was It Like When We Lost The Last Of Our …

What Was It Like When We Lost The Last Of Our Antimatter?

“The Cosmic Microwave Background’s temperature was first measured to this precision back in 1992, with the first data release of NASA’s COBE satellite. But the neutrino background imprints itself in a very subtle way, and wasn’t detected until 2015. When it was finally discovered, the scientists who did the work found a phase shift in the Cosmic Microwave Background’s fluctuations that enabled them to determine, if neutrinos were massless today, how much energy they’d have at this early time. 

Their results? The Cosmic Neutrino Background had an equivalent temperature of 1.96 ± 0.02 K, in perfect agreement with the Big Bang’s predictions.”

Throughout the very early Universe, space was filled with matter and antimatter, which spontaneously self-create from pure Energy via Einstein’s famous E = mc^2. However, as the Universe cools and expands, less energy becomes available to make new particles and antiparticles. Quarks, muons, taus, baryons, mesons, and gauge bosons all are gone by time the Universe is just 25 microseconds old. But positrons, the counterpart of antielectrons, remain until the Universe is a full 3 seconds old! Their existence leads to a crazy prediction: that there should be a cosmic neutrino background at a different temperature from the cosmic microwave background: 1.95 K instead of 2.73 K.

We have verified this, and hence, one of the Big Bang’s craziest predictions, with data collected 13.8 billion years onward! Come learn what it was like when the Universe lost the last of its antimatter.

One Simple Reason Why Touching The Sun Is So H…

One Simple Reason Why Touching The Sun Is So Hard

“It doesn’t simply take a suite of clever instruments to measure the Sun up close, although the Parker Solar Probe has those. It isn’t enough to have a thick, carbon-composite shield to withstand the incredible radiation and temperatures present in close proximity to the Sun, although the Parker Solar Probe has those, too. It also requires an incredibly complex, intricate plan to insert yourself into a stable orbit that’s capable of bringing you closer to the Sun than anything else ever has before.”

If there’s one law of physics that most people know, it’s Newton’s first law. Objects at rest remain at rest, and objects in motion remain in uniform motion, unless they’re acted on by an outside force. This applies not just to straight-line motions, but to orbiting motions as well. It isn’t just momentum that’s conserved in physics, but angular (or rotational) momentum, too. In order to touch the Sun, the Parker Solar Probe has to somehow get rid of a tremendous amount of angular momentum, and rockets alone aren’t powerful enough to do it. The trick? You have to use the other planets in the Solar System, and give up your angular momentum to them. The Parker Solar Probe will pass close by Venus a record seven times in order to do this, coming within less than 4 million miles of the Sun when they’re all over.

We’ve never touched the Sun before, but thanks to new technology, an ambitious mission, and an incredible flight plan, we’re about to accomplish what was once unthinkable.

First Stars Formed No Later Than 250 Million Y…

First Stars Formed No Later Than 250 Million Years After The Big Bang, With Direct Proof

“We see MACS1149-JD1 as it was 530 million years after the Big Bang, while inside, it has a special signature: oxygen. Oxygen is only produced by previous generations of stars, indicating that this galaxy is already old.

MACS1149-JD1 was imaged with microwave (ALMA), infrared (Spitzer), and optical (Hubble) data combined.

The results indicate that stars existed nearly 300 million years before our observations.”

One of the great quests of astronomers today is to measure and locate the very first stars in the Universe. As far back as Hubble can see, to when the Universe was just 3-5% its current age, the Universe is still full of galaxies, even though they’re smaller and bluer than the ones we have today. But within these galaxies, we can also find evidence that the stars in there aren’t the very first ones; they contain evidence for prior generations of stars in their spectral signatures. From the second-most distant galaxy ever discovered, itself just 530 million years after the Big Bang, we see evolved stars. They indicate that the very first ones formed no later than 250 million years after the Big Bang.

The James Webb Space Telescope will be able to see that far! In less than 3 years, we’ll peer beyond where we’ve ever seen before. And there will no doubt be something breathtaking to look at.

Ask Ethan: Is Spacetime Really A Fabric? “I&r…

Ask Ethan: Is Spacetime Really A Fabric?

“I’d like somebody to finally acknowledge and admit that showing balls on a bed sheet doesn’t cut it as a picture of reality.”

Okay, I admit it: visualizing General Relativity as balls on a bedsheet doesn’t make a whole lot of sense. For one, if this is what gravity is supposed to be, what pulls the balls “down” onto the bedsheet? For another, if space is three dimensional, why are we talking about a 2D “fabric” of space? And for another, why do these lines curve away from the mass, rather than towards it?

It’s true: this visualization of General Relativity is highly flawed. But, believe it or not, all visualizations of General Relativity inherently have similar flaws. The reason is that space itself is not an observable thing! In Einstein’s theory, General Relativity provides the link between the matter and energy in the Universe, which determines the geometric curvature of spacetime, and how the rest of the matter and energy in the Universe moves in response to that. In this Universe, we can only measure matter and energy, not space itself. We can visualize it how we like, but all visualizations are inherently flawed.

Come get the story of how to make as much sense as possible out of the Universe we actually have.

What Happens When Planets, Stars, And Black Ho…

What Happens When Planets, Stars, And Black Holes Collide?

Brown dwarf collisions. Want to make a star, but you didn’t accumulate enough mass to get there when the gas cloud that created you first collapsed? There’s a second chance available to you! Brown dwarfs are like very massive gas giants, more than a dozen times as massive as Jupiter, that experience strong enough temperatures (about 1,000,000 K) and pressures at their centers to ignite deuterium fusion, but not hydrogen fusion. They produce their own light, they remain relatively cool, and they aren’t quite true stars. Ranging in mass from about 1% to 7.5% of the Sun’s mass, they are the failed stars of the Universe.

But if you have two in a binary system, or two in disparate systems that collide by chance, all of that can change in a flash.”

Nothing in the Universe exists in total isolation. Planets and stars all have a common origin inside of star clusters; galaxies clump and cluster together and are the homes for the smaller masses in the Universe. In an environment such as this, collisions between objects are all but inevitable. We think of space as being extremely sparse, but gravity is always attractive and the Universe sticks around for a long time. Eventually, collisions will occur between planets, stars, stellar remnants, and black holes.

What happens when they run into one another? Unbelievably, we not only know, we have the evidence to back it up!

This Is Why Comets Glow An Eerie Green Color …

This Is Why Comets Glow An Eerie Green Color

“But even though things aren’t looking particularly good for this comet, there’s always a chance it will surprise us. Furthermore, the features that you can expect for this comet — the ion tail, the dust tail, the coma, and the nucleus — are common to practically all comets that enter our inner Solar System. When a comet gets warm enough, it creates an extended, gas-rich cloud known as a coma around its nucleus. If the coma contains carbon-nitrogen and carbon-carbon bonds, the Sun’s ultraviolet light will excite the electrons inside it, causing them to emit a green glow when they drop down in energy. And whenever you see that green glow, know that there’s a chance of the comet’s nucleus splitting apart. It may not happen this time, or even most times, but there’s a chance for a visually spectacular show. When it comes to skywatching, it’s hard to ask for more.”

We typically think of comets as frozen mixes of ice and rock, but they’re so much more. There’s dust and volatile compounds present, and when the light and heat from the Sun interacts with the surface, it kicks up molecules into a gaseous, diffuse coma. This coma then gets struck by the ultraviolet light from the Sun. The dust particles get accelerated, creating the main comet tail you’re used to, but there are gas particles in the coma that simply get kicked to higher energies. If there’s enough cyanogen (CN) and diatomic carbon (C2) molecules present, they’ll create a green color due to their atomic transitions. And whenever you see that color, know that there’s the potential for the cometary nucleus to split, creating a spectacular outburst.

This may not happen for the “Incredible Hulk” comet lighting our skies today, but there’s always a chance. Don’t miss yours!

What Was It Like When We First Made Protons An…

What Was It Like When We First Made Protons And Neutrons?

“But at this stage, the biggest new thing that occurs is that particles are no longer individual-and-free on all scales. Instead, for the first time, the Universe has created a stable, bound state of multiple particles. A proton is two up and one down quark, bound by gluons, while a neutron is one up and two down quarks, bound by gluons. Only because we created more matter than antimatter do we have a Universe that has protons and neutrons left over; only because the Higgs gave rest mass to the fundamental particles do we get these bound, atomic nuclei.

Owing to the nature of the strong force, and the tremendous binding energy that occurs in these stretched-spring-like interactions between the quarks, the masses of the proton and neutron are some 100 times heavier than the quarks that make them up. The Higgs gave mass to the Universe, but confinement is what gives us 99% of our mass. Without protons and neutrons, our Universe would never be the same.”

The very early Universe looks nothing like our Universe today. Not only are there no stars or galaxies, but there weren’t any atoms or atomic nuclei. If we go back early enough, there weren’t even protons or neutrons, but free quarks (and antiquarks) instead. This era lasted for just 10-to-20 microseconds in the early Universe, but the story of how we went from a quark-gluon plasma to a Universe filled with protons and neutrons is a fascinating true part of our shared cosmic history.

Here’s what the Universe was like when we first made protons and neutrons, along with a list of all the things we needed to line up to lead to the Universe we recognize today!

Please dear community, use these four minutes …

Please dear community, use these four minutes to realize the industrialized exploitation and murder which is supported and made even possible by our consumption. Sentient beings – just like you and me – are killed every second. They are striving for happiness and joy but they are forced to experience pure suffering every day.

“To live is to suffer, to survive is to find some meaning in the suffering.” – Friedrich Nietzsche

For them there is no meaning in the suffering at all. You can stop it, be compassionate – go vegan.

amore-more-ore-re: physicsforbunnies:Carl Jun…

amore-more-ore-re:

physicsforbunnies:

Carl Jung

So the loneliness created by his own pride is satanic.
The pride of believing that our thoughts are more important than those of others.
Pride is to cut oneself off from others.
The proud man creates his own Hell on Earth.

Fuck off