Chamaeleon Dark Nebulas : Sometimes The Dark Dust Of Interstellar Space Has An Angular Elegance. Such

Chamaeleon Dark Nebulas : Sometimes the dark dust of interstellar space has an angular elegance. Such is the case toward the far-south constellation of Chamaeleon. Normally too faint to see, dark dust is best known for blocking visible light from stars and galaxies behind it. In this four-hour exposure, however, the dust is seen mostly in light of its own, with its strong red and near-infrared colors giving creating a brown hue. Contrastingly blue, the bright star Beta Chamaeleontis is visible just to the right of center, with the dust that surrounds it preferentially reflecting blue light from its primarily blue-white color. All of the pictured stars and dust occur in our own Milky Way Galaxy with – but one notable exception: the white spot just below Beta Chamaeleontis is the galaxy IC 3104 which lies far in the distance. Interstellar dust is mostly created in the cool atmospheres of giant stars and dispersed into space by stellar light, stellar winds, and stellar explosions such as supernovas. via NASA

IS THE UNIVERSE INFINITE??

Blog# 187

Wednesday, April 27th, 2022

Welcome back,

It’s one of the most compelling questions you could possibly ask, one that humanity has been asking since basically the beginning of time: What’s beyond the known limits? What’s past the edge of our maps? The ultimate version of this question is, What lies outside the boundary of the universe?

The answer is — well, it’s complicated.

To answer the question of what’s outside the universe, we first need to define exactly what we mean by “universe.” If you take it to mean literally all the things that could possibly exist in all of space and time, then there can’t be anything outside the universe. Even if you imagine the universe to have some finite size, and you imagine something outside that volume, then whatever is outside also has to be included in the universe.

Even if the universe is a formless, shapeless, nameless void of absolutely nothing, that’s still a thing and is counted on the list of “all the things” — and, hence, is, by definition, a part of the universe.

If the universe is infinite in size, you don’t really need to worry about this conundrum. The universe, being all there is, is infinitely big and has no edge, so there’s no outside to even talk about.

Oh, sure, there’s an outside to our observable patch of the universe. The cosmos is only so old, and light only travels so fast. So, in the history of the universe, we haven’t received light from every single galaxy. The current width of the observable universe is about 90 billion light-years. And presumably, beyond that boundary, there’s a bunch of other random stars and galaxies.

But past that? It’s hard to tell.

Cosmologists aren’t sure if the universe is infinitely big or just extremely large. To measure the universe, astronomers instead look at its curvature. The geometric curve on large scales of the universe tells us about its overall shape. If the universe is perfectly geometrically flat, then it can be infinite. If it’s curved, like Earth's surface, then it has finite volume.

Current observations and measurements of the curvature of the universe indicate that it is almost perfectly flat. You might think this means the universe is infinite. But it’s not that simple. Even in the case of a flat universe, the cosmos doesn’t have to be infinitely big. Take, for example, the surface of a cylinder.

It is geometrically flat, because parallel lines drawn on the surface remain parallel (that’s one of the definitions of “flatness”), and yet it has a finite size. The same could be true of the universe: It could be completely flat yet closed in on itself.

But even if the universe is finite, it doesn’t necessarily mean there is an edge or an outside. It could be that our three-dimensional universe is embedded in some larger, multidimensional construct. That’s perfectly fine and is indeed a part of some exotic models of physics. But currently, we have no way of testing that, and it doesn’t really affect the day-to-day operations of the cosmos.

And I know this is extremely headache-inducing, but even if the universe has a finite volume, it doesn't have to be embedded.

When you imagine the universe, you might think of a giant ball that’s filled with stars, galaxies and all sorts of interesting astrophysical objects. You may imagine how it looks from the outside, like an astronaut views Earth from a serene orbit above.

But the universe doesn’t need that outside perspective in order to exist. The universe simply is. It is entirely mathematically self-consistent to define a three-dimensional universe without requiring an outside to that universe. When you imagine the universe as a ball floating in the middle of nothing, you’re playing a mental trick on yourself that the mathematics does not require.

Granted, it sounds impossible for there to be a finite universe that has nothing outside it. And not even “nothing” in the sense of an empty void — completely and totally mathematically undefined. In fact, asking “What’s outside the universe?” is like asking “What sound does the color purple make?” It’s a nonsense question, because you’re trying to combine two unrelated concepts.

It could very well be that our universe does indeed have an “outside.” But again, this doesn’t have to be the case. There’s nothing in mathematics that describes the universe that demands an outside.

If all this sounds complicated and confusing, don’t worry. The entire point of developing sophisticated mathematics is to have tools that give us the ability to grapple with concepts beyond what we can imagine. And that’s one of the powers of modern cosmology: It allows us to study the unimaginable.

Originally published on https://www.space.com

COMING UP!!

(Saturday, April 30th, 2022)

“WHAT IS THE ELECTRON CLOUD THEORY??”

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of-finite-jurisdiction

2 years ago

Why is this heat so hot 😩

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of-finite-jurisdiction

2 years ago

Comet Leonard

A Dusty Fingerprint in Space

An image from NASA’s James Webb Space Telescope shows a bright dot at the center of star-filled black space. The bright dot is actually two stars meeting, as their orbits bring them together every 8 years. The stellar pair are surrounded by 17 rings of gas and dust that appear orangish gray. The rings have a slight rectangular shape and are very clear and defined starting at about 1 o’clock on a clockface. The rings start to break up a bit to our view traveling clockwise around the image. As you arrive at the 12:40 position, only parts of about six rings can be seen as they disappear from view.

A new image from NASA's James Webb Space Telescope reveals a remarkable cosmic sight: at least 17 concentric dust rings emanating from a pair of stars. Just 5,300 light-years from Earth, the star duo are collectively known as Wolf-Rayet 140. Each ring was created when the two stars came close together and their stellar winds (streams of gas they blow into space) collided so forcefully that some of the gas was compressed into dust. The stars' orbits bring them together about once every eight years, and forms a half-shell of dust that looks like a ring from our perspective. Like a cosmic fingerprint, the 17 rings reveal more than a century of stellar interactions—and the "fingerprint" belonging to Wolf-Rayet 140 may be equally unique. Other Wolf-Rayet stars produce dust, but no other pair are known to produce rings quite like Wolf-Rayet 140.

Learn more about Wolf-Rayet 140.

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of-finite-jurisdiction

2 years ago

how I sleep at night knowing there are stars and planets and galaxies above my roof