mysticstronomy

[mysticstronomy]

IS THERE A GALAXY WITHOUT DARK MATTER??

Blog#516

Wednesday, June 25th, 2025,

Welcome back,

Our picture of cosmic evolution could be thrown into doubt by the discovery of a massive galaxy that seems to lack dark matter.

Dark matter, which accounts for around 85% of the matter in the universe, seems to be absent from the galaxy NGC 1277, part of the Perseus Cluster of galaxies. The galaxy, located 240 million light-years from Earth, is the first Milky Way-sized conglomeration of stars, planets, dust and gas found to be missing dark matter.

"This result does not fit in with the currently accepted cosmological models, which include dark matter," the leader behind the discovery and University of La Laguna researcher Sebastién Comerón said in a statement.

Dark matter is effectively invisible because it does not interact with light like the everyday matter that composes stars, planets, and us. Its presence can be inferred by its gravitational interactions, however. The existence of this shadowy substance was first posited when astronomers observed massive galaxies rotating so fast they would fly apart if it weren't for the gravitational influence of some unseen mass holding them together.

This fact resulted in scientists theorizing that all large galaxies are wrapped in an envelope of dark matter, and this has become an important assumption in the development of theories of galactic evolution. But the discovery of a galaxy that appears to haven no dark matter challenges that assumption.

The scientists behind this revelation have a few ideas about why NGC 1277 is so deficient in dark matter.

"One is that the gravitational interaction with the surrounding medium within the galaxy cluster in which this galaxy is situated has stripped out the dark matter," team member and University of La Laguna researcher Anna Ferré-Mateu. "The other is that the dark matter was driven out of the system when the galaxy formed by the merging of protogalactic fragments, which gave rise to the relic galaxy."

The team isn't totally satisfied with either explanation and will, therefore, continue investigating NGC 1277 with the William Herschel Telescope (WHT) at the Roque de los Muchachos Observatory on the Canary Island of La Palma.

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

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A UNIVERSE WITHOUT DARK MATTER??

Blog#515

Saturday, June 21st, 2025,

Welcome back,

Our current picture of the cosmos is one of an expanding universe governed by gravity, born from a hot beginning and stretched uniformly across vast scales. But this vision only holds together when we invoke mysterious unseen forces—inflation, dark energy, and more. This prevailing cosmological model—also known as the Big Bang or Lambda-CDM (ΛCDM)—has countless problems, but it is mainstream, and almost all the scientific and economic efforts of the community of astrophysicists and theoretical physicists dealing with the question are focused on the search for evidence that can confirm it.

Other models explaining the cosmos—for example those without a Big Bang beginning, without an inflationary period, without energy and dark matter—do not receive the same attention. But if any of them are correct, the cosmos could be very different from the mainstream version we have been taught as dogma.

The existence of dark or invisible matter detectable only through its gravitational influence has been known by astronomers for a long time now.

In 1844, Friedrich Wilhelm Bessel argued that the observed proper motions of the stars Sirius and Procyon could be explained only in terms of the presence of faint companion stars. In 1846, Urbain Jean Joseph Le Verrier and John Couch Adams independently predicted the existence of Neptune based on calculations of the anomalous motions of Uranus. Le Verrier later proposed the existence of the planet Vulcan to explain anomalies in the orbit of Mercury, but he failed on that occasion because the solution was not invisible matter but a change of gravitational laws, as was solved years later by Einstein with General Relativity.

In 1933, Swiss astronomer Fritz Zwicky was studying rich clusters of galaxies—large clusters containing hundreds or thousands of individual galaxies. He applied the virial theorem to calculate how much matter should be present based on the gravitational forces needed to hold these clusters together. There appeared to be about 60 times more matter than could be accounted for by all the visible stars and gas. In 1939, Horace W. Babcock first showed the need for dark matter for an individual galaxy by measuring how fast stars were rotating in the outer regions of the M31 galaxy, also known as Andromeda. The rotational velocity was faster than it should have been based on visible matter. At that time, however, the majority of astronomers were not yet convinced of the need for dark matter haloes in galaxies.

Originally published on https://iai.tv

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"IS THERE A GALAXY WITHOUT DARK MATTER??"

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IS SPACE TIME AFFECTED BY GRAVITY??

Blog#514

Wednesday, June 18th, 2025,

Welcome back,

You may have heard the seemingly far-out notion that gravity bends light, space and time, and wondered whether this was mere science fiction.

To determine whether this statement is actually true, we need to determine whether gravity, as most of us understand it, truly exists.

At school we are told that gravity is an attractive force. That the Moon orbits around the Earth because our planet pulls on it.

This, after all, is how Isaac Newton described gravity.

However, we've had a more complete picture of gravity for over a century: Einstein's General Theory of Relativity.

General Relativity describes how mass distorts the fabric of the universe, a fabric known as spacetime.

Picture this by imagining a bedsheet held tightly at the four corners, with a bowling ball placed in the centre to represent the Earth.

The sheet will sag in the middle. You could then take a tennis ball and roll it around the rim of the dip in the sheet.

In other words, you could make the tennis ball orbit the bowling ball. Crucially, though, there's no force of attraction here.

The bowling ball isn't pulling on the tennis ball. Instead the bowling ball is distorting the shape of the fabric and the tennis ball is simply following that distortion.

So the attractive 'force' of gravity is actually an illusion. Gravity is mere geometry.

As gravity wells are distortions in spacetime, they also distort time as well as space.

Picture a rather peculiar kind of clock. It is made of two mirrors with light bouncing between them.

Every time the light hits a mirror the clock ticks.

If you take this clock into a gravity well then the spacetime between the mirrors will be distorted and it will take longer for the light to travel between the mirrors.

In other words, the clock will tick less frequently. Time runs more slowly the deeper inside a gravity well you are.

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

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"A UNIVERSE WITHOUT DARK MATTER??"

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COULD WE BUILD SPACE TIME COMPUTERS THAT RUN ON GRAVITY??

Blog#513

Saturday, June 14th, 2025,

Welcome back,

Imagine a computer that doesn't run on silicon or electricity — but on space-time itself.

A new mathematical breakthrough proposes a jaw-dropping idea: using gravity — the bending of space and time — as a computation force. That's right. We might one day build computers that run on the fabric of the universe itself.

The Big Idea: Gravity as a Logic Gate?

In general relativity, gravity isn't a force — it's a curvature of space and time caused by mass and energy. Black holes, neutron stars, even gravitational waves — all distort the structure of space-time.

Now, theoretical physicists have devised a new framework that enables us to detect whether information has been altered by the warping of space-time. That is to say: they've figured out how to tell if a message was distorted by gravity itself.

This isn't simply an issue of detecting changes — it's an issue of developing a foundation in which gravity becomes a part of the computing process. This implies that gravitational fields can not only affect the movement of mass and light, but how we calculate data too.

A Future Beyond Silicon?

Purely theoretical still, this study implies a radically new paradigm of computation:

Space-time logic gates: Instead of electrical signals flipping transistors, one could modulate signals with engineered gravitational curvatures.

Gravity-driven information flow: One could encode information in the way gravitational fields bend light or slow down signals.

Geometry-based computation: Doing math with the *shape* of the universe. Literally.

It's a move towards what you might call a space-time computer— a computer that "thinks" in terms of bends, curves, and warps in the universe.

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WHAT IS THE BIGGEST MYSTERY IN SPACE??

Blog#512

Saturday, June 7th, 2025,

Welcome back,

While the James Webb Space Telescope (JWST) has answered many questions about the cosmos, there is one problem it has made significantly worse. The $10 billion space telescope has excelled in discovering supermassive black holes at the dawn of the universe, and while that sounds like a good thing, it has been a little worrying for scientists.

Supermassive black holes have masses millions or billions of times that of the sun and are thought to reside at the hearts of all large galaxies.

No single star has the mass needed to collapse and create a supermassive black hole, so scientists know these behemoths aren't born like more diminutive stellar-mass black holes, which have masses around 10 to 100 times that of the sun.

Scientists think supermassive black holes grow to monstrous sizes via merger chains of progressively massive black holes. Their growth is also thought to be aided by the rapid consumption, or accretion, of gas and dust from their host galaxies.

Here's the problem: As our understanding of that process currently stands, it should take at least 1 billion years. That means that, when JWST turns up supermassive black holes with millions of solar masses as early as 600 million years after the Big Bang, it's a real problem for our models of cosmic evolution. And these discoveries just keep coming.

"It's like seeing a family walking down the street, and they have two 6-foot teenagers, but they also have with them a 6-foot-tall toddler," John Reagan, Royal Society research fellow at Maynooth University, previously told Space.com. "That's a bit of a problem. How did the toddler get so tall? And it's the same for supermassive black holes in the universe. How did they get so massive, so quickly?"

Originally published on www.Space. Com

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DID THE UNIVERSE EXIST FOREVER??

Blog#511

Wednesday, June 4th, 2025,

Welcome back,

The Universe has not existed forever. It was born. Around 13.82 billion years ago, matter, energy, space – and time – erupted into being in a fireball called the Big Bang. It expanded and, from the cooling debris, there congealed galaxies – islands of stars of which our Milky Way is one among about two trillion. This is the Big Bang theory.

A universe popping into existence out of nothing is so bonkers that scientists had to be dragged kicking and screaming to the idea. But the evidence is compelling. The galaxies are flying apart like pieces of cosmic shrapnel. And the heat of the Big Bang is still around us.

Greatly cooled by cosmic expansion, this ‘afterglow’ appears not as visible light but principally as microwave radiation – the ‘cosmic background radiation’, which was discovered by radio astronomers in 1965.

When a stick of dynamite explodes, the detonation occurs in one place and shrapnel flies into the void. In the Big Bang, there was no centre and no pre-existing void, so it didn’t happen at any ‘location’. Space itself popped into existence and began expanding everywhere at once.

Astronomy books often liken the Universe to a rising cake, with raisins representing galaxies. As the cake grows, raisins recede from each other, with no centre of expansion – just like the Big Bang. But of course, a cake has an edge, unlike the Universe, which may go on forever. No analogy is perfect!

In the beginning of the Big Bang there was the inflationary vacuum. When it doubled its volume, it doubled its energy; when it tripled its volume, it tripled its energy. If banknotes were like this and you pulled apart a stack, ever more would appear. Physicists call inflation the ‘ultimate free lunch’!

The inflationary vacuum expanded ever faster. But it was a ‘quantum’ thing. And quantum things are fundamentally unpredictable. Randomly, all over the inflationary vacuum, parts of it ‘decayed’ into ordinary, everyday vacuum.

Think of tiny bubbles forming in a vast ocean. In each bubble, the inflationary vacuum disappeared, but its enormous energy had to go somewhere.

It went into creating matter and heating it. It went into creating a Big Bang. Our Big Bang Universe is merely one such bubble among a possible infinity of other Big Bang universes in the ever-expanding inflationary vacuum!

To start all this, a chunk of inflationary vacuum of only a kilogram was needed. Incredibly, the laws of quantum theory permit this to pop into existence out of nothing.

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

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WAS THE UNIVERSE 'TIMELESS' BEFORE THE BIG BANG??

Blog#510

Saturday, May 31st, 2025,

Welcome back,

As far back as we can observe in our Universe, time always behaved in exactly the same fashion we’re familiar with: ticking away, relentlessly, at the same rate for all observers. Bring your clock to the surface of the Earth? The bottom of the ocean? Into orbit in space? Near the event horizon of a black hole? Or speeding through intergalactic space at close to the speed of light? It doesn’t matter. The amount of time it takes for regular events to occur — for a second to tick by, for an atomic transition to occur, for a photon of a specific wavelength to have one “wave” pass by you, etc. — is going to be identical for any observer under any of those conditions. In fact, the rate at which time passes for themselves, at one second-per-second, is something all observers can agree on.

Sure, relativity is weird in a lot of ways, both when you move close to the speed of light or when the curvature of spacetime is very strong. Lengths contract, time durations dilate, and different observers draw different conclusions for one another versus for themselves. But time still passes, and relativity allows us to reconcile those differences. But what about if we go to an unfamiliar place; what if we consider what happens before the Big Bang? That’s what Justin Skit wants to know, asking:

“Can you help me understand what’s going on with time during cosmic inflation? I know inflation starts and then the big bang. But if the era before the big bang was timeless how does that work?”

It’s an excellent question, and one that compels us to go very deep into theoretical physics territory. Let’s dive in and see what we learn!

The first thing you have to understand is that time, in physics, is different from how we normally conceive of it.

When you think about time, you probably think of it as a continuum: as a “line” of sorts that always marches forward at the same rate for anyone experiencing it. In your day-to-day life, you’ve experienced time in a similar fashion for its entire duration: it seems to pass by, in a uniform, measurable fashion, allowing you to mark “when” any event occurred. All of the events that have occurred in the past are forever immutable; they have occurred and cannot be changed. All of the events that will occur in the future are as of yet still undetermined; the actions and events that unfold from now until the time when they occur can still affect them.

Originally published on https://bigthink.com

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THE END OF THE UNIVERSE COULD BEGIN WITH A QUANTUM BUBBLE!!

Blog#509

Welcome back,

Wednesday, May 28th, 2025,

Most people have never heard of vacuum decay, but if it happened it would be the biggest natural disaster in the universe. Sure, an asteroid could destroy a city or wipe out life on Earth. A supernova could fry the ozone layer. If a blast of energy from a spinning black hole hit our planet, it could rip apart the entire solar system. As dramatic as these disasters are, they’d still leave behind rocks, gas and dust. With time that matter could come together again, making new stars and planets and maybe life.

Vacuum decay is different. This cataclysm would result from a change in the Higgs field, a quantum field that pervades all of space. It would be triggered by pure chance, creating a bubble that would expand at almost the speed of light, transforming all in its path. Inside that bubble the laws of physics we take for granted would change, making matter as we know it (and, consequently, life) impossible.

According to physicists’ current best estimates, vacuum decay is extremely unlikely, with an almost unthinkably small chance of its taking place close enough to our part of the universe to affect us. Still, the chance isn’t zero, and some recent estimates suggest the likelihood might be slightly less minuscule than we used to think. Ultimately, though, the possibility of an apocalyptic quantum bubble shouldn’t cause anyone to lose any sleep.

Even so, scientists have been studying how and why this scenario might play out. The answers to these questions don’t just reveal some fascinating aspects of the quantum world—they may also turn the questions on their heads: rather than making us worry about the threat a vacuum bubble poses, the fact that the universe has survived this long without one may teach us something about the deepest unsolved problems in physics.

The word “vacuum” evokes the idea of empty space, and that’s not too far from its meaning in the phrase “vacuum decay.” For physicists, however, “empty” itself is relative.

All the objects we’re used to—every animal, vegetable and mineral—are made up of atoms, and those atoms are made up of ripples in quantum fields. Each field is like a setting on a kind of universal control panel. If you could jiggle the electron switch on the control panel, you’d see an electron pop into existence. Most of these switches have a default value of zero: electrons aren’t likely to be in most places, for example. These defaults are sticky—it takes effort, in the form of energy, to push a switch out of its default position. How much energy it requires is determined by Albert Einstein’s famous equation E = mc2, which defines the relation between energy and mass: the more massive a particle, the stickier the default for the switch of its field.

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

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WHY IS THERE NO SOUND IN SPACE??

Blog#508

Welcome back,

Saturday, May 24th, 2025,

In space, no one can hear you scream.

You may have heard this saying. It’s the tagline from the famous 1979 science fiction movie “Alien.” It’s a scary thought, but is it true? The simple answer is yes, no one can hear you scream in space because there is no sound or echo in space.

To understand why there’s no sound in space, first consider how sound works. Sound is a wave of energy that moves through a solid, a liquid or a gas.

Sound is a compression wave. The energy created when your vocal cords vibrate slightly compresses the air in your throat, and the compressed energy travels outward.

A good analogy for sound is a Slinky toy. If you stretch out a Slinky and push hard on one end, a compression wave travels down the Slinky.

When you talk, your vocal cords vibrate. They jostle air molecules in your throat above your vocal cords, which in turn jostle or bump into their neighbors, causing a sound to come out of your mouth.

Sound moves through air the same way it moves through your throat. Air molecules near your mouth bump into their neighbors, which in turn bump into their neighbors, and the sound moves through the air. The sound wave travels quickly, about 760 miles per hour (1,223 kilometers per hour), which is faster than a commercial jet.

So what about in space?

Space is a vacuum, which means it contains almost no matter. The word vacuum comes from the Latin word for empty.

Sound is carried by atoms and molecules. In space, with no atoms or molecules to carry a sound wave, there’s no sound. There’s nothing to get in sound’s way out in space, but there’s nothing to carry it, so it doesn’t travel at all. No sound also means no echo. An echo happens when a sound wave hits a hard, flat surface and bounces back in the direction it came from.

By the way, if you were caught in space outside your spacecraft with no spacesuit, the fact that no one could hear your cry for help is the least of your problems. Any air you still had in your lungs would expand because it was at higher pressure than the vacuum outside. Your lungs would rupture. In a mere 10 to 15 seconds, you’d be unconscious due to a lack of oxygen.

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

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WHAT IS THE COLDEST PLACE IN THE UNIVERSE??

Blog#507

Welcome back,

Wednesday, May 21st, 2025,

The coldest place in the universe is the Boomerang Nebula, the chilliest object ever found so far. It's located some 5,000 light-years away from Earth in the constellation Centaurus.

The Boomerang Nebula is a reflecting cloud of dust and ionized gases — a young planetary nebula with a dying red giant star at its center. Once a star much like our sun, it has been shedding its outer layers as expected during the last stages of its life. But it has been found to be losing its mass about 100 times faster than other similar dying stars.

What's more, it's doing so at a jaw-dropping 100 billion times faster than Earth's sun. According to NASA, this has actually resulted in nearly one-and-a-half times the mass of our sun being lost by the central star over the past 1,500 years. And, because the gases are being thrown off so fast — and at a rate of 101 miles per second (164 km/s)) — it's blasting away a lot of heat energy.

The upshot of this is a very cold region of space and it's best expressed by recapping the lowest limit of the thermodynamic temperature scale: absolute zero. On the Celsius scale this is –273.15 degrees and on the Fahrenheit scale it is –459.67 degrees. So how does the Boomerang Nebula compare?

The Boomerang Nebula's deep interior temperature is a teeth-chattering –458 degrees Fahrenheit or –272 degrees Celsius, meaning that the Boomerang Nebula is just a degree Celsius above absolute zero. That places it at over three times chillier than the temperature recorded across Dome Fuji, Antarctica in 2010, which was recorded at a freezing -199.8 degrees Fahrenheit (-93.2 degrees Celsius), according to The Independent.

The Boomerang Nebula is so cold that it's even lower than the temperature of the cosmic microwave background (CMB) left over from the Big Bang (-454.7 degrees Fahrenheit, -270.4 degrees Celsius). Indeed the CMB's light is actually absorbed by the Boomerang Nebula and this was quickly spotted when the nebula was first discovered in 1980.

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

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WHY IS SPACE BLACK??

Blog#506

Welcome back,

Saturday, May 17th, 2025,

This question, which seems simple, is actually very difficult to answer! It is a question that many scientists pondered for many centuries - including Johannes Kepler, Edmond Halley , and German physician-astronomer Wilhelm Olbers.

There are two things to think about here. Let's take the easy one first and ask "why is the daytime sky blue here on Earth?" That is a question we can answer. The daytime sky is blue because light from the nearby Sun hits molecules in the Earth's atmosphere and scatters off in all directions.

The blue color of the sky is a result of this scattering process. At night, when that part of Earth is facing away from the Sun, space looks black because there is no nearby bright source of light, like the Sun, to be scattered. If you were on the Moon, which has no atmosphere, the sky would be black both night and day. You can see this in photographs taken during the Apollo Moon landings.

So, now on to the harder part - if the universe is full of stars, why doesn't the light from all of them add up to make the whole sky bright all the time? It turns out that if the universe was infinitely large and infinitely old, then we would expect the night sky to be bright from the light of all those stars. Every direction you looked in space you would be looking at a star. Yet we know from experience that space is black! This paradox is known as Olbers' Paradox. It is a paradox because of the apparent contradiction between our expectation that the night sky be bright and our experience that it is black.

Many different explanations have been put forward to resolve Olbers' Paradox. The best solution at present is that the universe is not infinitely old; it is somewhere around 15 billion years old. That means we can only see objects as far away as the distance light can travel in 15 billion years. The light from stars farther away than that has not yet had time to reach us and so can't contribute to making the sky bright.

Another reason that the sky may not be bright with the visible light of all the stars is because when a source of light is moving away from you, the wavelength of that light is made longer (which for light means more red.) This means that the light from stars that are moving away from us will become shifted towards red, and may shift so far that it is no longer visible at all. (Note: You hear the same effect when an ambulance passes you, and the pitch of the siren gets lower as the ambulance travels away from you; this effect is called the Doppler Effect).

Originally published on https://starchild.gsfc.nasa.gov

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WHAT IS A GALAXY??

Blog#505

Welcome back,

Wednesday, May 14th, 2025,

The word itself comes from galaktikós kyklos, or “milky circle,” the ancient Greek term for the Milky Way, our home galaxy.

In modern times, though, we use “galaxy” more generically to refer to any large system of stars, gas, dust and dark matter, all held together by their mutual gravity. That’s actually not a bad definition, except for the small fact that not every galaxy has all these features.

There are galaxies without any detectable gas and dust, and some that seem to have little or no dark matter. I suppose the common thread is that they do all have stars, but even then we run into trouble because not all gravitationally bound systems of stars rate as galaxies.

Very generally speaking, galaxies are tens of thousands to hundreds of thousands of light-years across and have millions to several trillions of stars. Our Milky Way, for example, is about 120,000 light-years wide and contains somewhere between approximately 100 billion to 400 billion stars.

It’s hard to get even a rough number because faint red dwarfs are the most common kind of stars, but they’re so dim they fade to invisibility even relatively close to our solar system.

Still, we do know the overall shape of our galaxy, which is a gigantic flattened disk with a central bulge of older, redder stars that is about 20,000 light-years wide. The structure of the disk is dominated by four major spiral arms and several smaller ones. These arms are dotted by huge clouds of gas and dust from which stars are born. Many of these stars are massive, luminous and blue, giving the spiral arms their characteristic azure hue. Because we’re inside the galaxy, mapping it is difficult, so many details of its structure remain to be determined.

Spirals are only one of four major classifications for galaxies; the others are elliptical, irregular and peculiar.

Elliptical galaxies would be better called spheroidal; they can be spherical but are more commonly elongated, a bit like a cotton ball. Some of the largest galaxies we know are elliptical, like the mighty M87 galaxy, which has several trillion stars. M87 sits in the center of the Virgo Cluster—a large group of galaxies bound together by gravity that boasts about 2,000 members. In fact, such giant ellipticals are common in the centers of galaxy clusters. These galaxies grow by eating other ones, both large and small, that venture too close to the cluster core, so the elliptical shape itself may be caused in part by this cannibalism process.

Not all ellipticals are huge, though: many are quite small. These are called “dwarf elliptical galaxies” and are satellites of larger galaxies. The Andromeda galaxy, for example, has many dwarf ellipticals orbiting it.

Ellipticals don’t have much gas in them, if any. They appear to have exhausted essentially all their gas by making stars long ago. Massive blue stars don’t live long; they explode as supernovae within millions of years of their birth, so a few billion years after its gas is depleted, an elliptical galaxy will look very red, dominated by ruddier lower-mass stars.

Peculiar galaxies are rare. They have all sorts of shapes but tend to be, well, odd. They are usually the result of galactic collisions, train wrecks on a cosmic scale. The mutual gravity of two interacting galaxies stretches and distorts their otherwise regular shapes, creating long, curving tails of flung-away stars. Sometimes, if a smaller galaxy plows right through the center of a larger one, the collision creates a ring galaxy, in which the stars and gas are splashed away from the larger galaxy’s center like ripples on a pond after a rock is dropped in.

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

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IS THE UNIVERSE INFINITE??

Blog#504

Welcome back,

Saturday, May 10th, 2025,

First, it’s still possible the universe is finite. All we know for sure (mostly for sure) is that it’s bigger than we can observe, essentially because the farthest edges of the universe we can see don’t look like edges. The observable universe is still huge, but it has limits. That’s because we know the universe isn’t infinitely old — we know the Big Bang occurred some 13.8 billion years ago.

That means that light has had “only” 13.8 billion years to travel. That’s a lot of time, but the universe is big enough that scientists are pretty sure that there’s space outside our observable bubble, and that the universe just isn’t old enough yet for that light to have reached us.

(In a fun twist, the universe has expanded since the Big Bang, so the objects that we see emitting light 13.8 billion years ago are now some 46 billion light-years away.)

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

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DO WE LIVE IN A GIANT VOID??

Blog#503

Welcome back,

Wednesday, May 7th, 2025,

One of the biggest mysteries in cosmology is the rate at which the universe is expanding. This can be predicted using the standard model of cosmology, also known as Lambda-cold dark matter (ΛCDM). This model is based on detailed observations of the light left over from the Big Bang – the so-called cosmic microwave background (CMB).

The universe’s expansion makes galaxies move away from each other. The further away they are from us, the more quickly they move. The relationship between a galaxy’s speed and distance is governed by “Hubble’s constant”, which is about 43 miles (70 km) per second per Megaparsec (a unit of length in astronomy). This means that a galaxy gains about 50,000 miles per hour for every million light years it is away from us.

But unfortunately for the standard model, this value has recently been disputed, leading to what scientists call the “Hubble tension”. When we measure the expansion rate using nearby galaxies and supernovas (exploding stars), it is 10% larger than when we predict it based on the CMB.

In our new paper, we present one possible explanation: that we live in a giant void in space (an area with below average density). We show that this could inflate local measurements through outflows of matter from the void. Outflows would arise when denser regions surrounding a void pull it apart – they’d exert a bigger gravitational pull than the lower density matter inside the void.

In this scenario, we would need to be near the centre of a void about a billion light years in radius and with density about 20% below the average for the universe as a whole – so not completely empty.

Such a large and deep void is unexpected in the standard model – and therefore controversial. The CMB gives a snapshot of structure in the infant universe, suggesting that matter today should be rather uniformly spread out. However, directly counting the number of galaxies in different regions does indeed suggest we are in a local void.

Originally published on https://theconversation.com

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"IS THE UNIVERSE INFINITE??"

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IS THE UNIVERSE IN EMPTY SPACE??

Blog#502

Welcome back,

Saturday, May 3rd, 2025,

When it comes to the physical Universe, the notion of “nothing” may truly be possible only in theory, not in practice. As we see the Universe today, it appears full of stuff: matter, radiation, antimatter, neutrinos, and even dark matter and dark energy, despite the fact that we don’t truly know the ultimate, fundamental nature of the latter two. Yet even if you took away every single quantum of energy, somehow removing it from the Universe entirely, you wouldn’t be left with an empty Universe. No matter how much you take out of it, the Universe will always generate new forms of energy.

How is this possible? It’s like the Universe itself doesn’t understand our idea of “nothing” at all; if we were to remove all the quanta of energy from our Universe, leaving behind only empty space, we would immediately expect that the Universe would be at absolute zero: with no energetic particles anywhere to be found. Yet that’s not the case at all. No matter how “empty” we artificially make the expanding Universe, the fact that it’s expanding would still spontaneously and unavoidably generate radiation. Even arbitrarily far into the future, or all the way back before the hot Big Bang, the Universe would never truly be empty. Here’s the science of why.

Here in our Universe today, it’s very clear that space is anything but empty. In every direction we look, we see:

stars, gas, dust, other galaxies, galaxy clusters, quasars,

high-energy cosmic particles (known as cosmic rays),

and radiation, both from starlight and left over from the Big Bang itself.

If we had better “eyes,” which is to say, superior tools at our disposal, we could also detect the signals that we know ought to be out there, but which cannot be detected with current technology.

We’d see gravitational waves from every mass that’s accelerating through a changing gravitational field. We’d “see” whatever is responsible for dark matter, rather than simply its gravitational effects. And we’d see black holes, both active and quiescent, rather than simply the ones that are emitting the greatest amounts of radiation.

All of what we see isn’t simply occurring in a static Universe, but rather in a Universe that’s evolving over time. What’s particularly interesting from a physical point of view is how our Universe is evolving. On a global scale, the fabric of our Universe — spacetime — is in the process of expanding, which is to say that if you put any two well-separated “points” down in your spacetime, you’ll find that the:

proper distance (as measured by an observer at one of the points) between those points,

the light-travel time between those points,

and the wavelength of the light that travels from one point to the other,

will all increase over time. The Universe is not just expanding, but also cooling concurrently as a result of the expansion. As light shifts to longer wavelengths, it also shifts towards lower energies and cooler temperatures; the Universe was hotter in the past and will be even colder in the future. And, through it all, the objects with mass and/or energy in the Universe gravitate, clumping and clustering together to form a great cosmic web.

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

COMING UP!!

(Wednesday, May 7th, 2025)

"DO WE LIVE IN A GIANT VOID??"

[mysticstronomy]

IS THE UNIVERSE THE INTERIOR OF A BLACK HOLE??

Blog#501

Welcome back,

Wednesday, April 30th, 2025

Without a doubt, since its launch, the James Webb Space Telescope (JWST) has revolutionized our view of the early universe, but its new findings could put astronomers in a spin. In fact, it could tell us something profound about the birth of the universe by possibly hinting that everything we see around us is sealed within a black hole.

The $10 billion telescope, which began observing the cosmos in the Summer of 2022, has found that the vast majority of deep space and, thus the early galaxies it has so far observed, are rotating in the same direction. While around two-thirds of galaxies spin clockwise, the other third rotates counter-clockwise.

In a random universe, scientists would expect to find 50% of galaxies rotating one way, while the other 50% rotate the other way. This new research suggests there is a preferred direction for galactic rotation.

The observations of 263 galaxies that revealed this strangely coordinated cosmic dance was collected as part of the James Webb Space Telescope Advanced Deep Extragalactic Survey, or "JADES."

"It is still not clear what causes this to happen, but there are two primary possible explanations," team leader Lior Shamir, associate professor of computer science at the Carl R. Ice College of Engineering, said in a statement. "One explanation is that the universe was born rotating. That explanation agrees with theories such as black hole cosmology, which postulates that the entire universe is the interior of a black hole.

"But if the universe was indeed born rotating, it means that the existing theories about the cosmos are incomplete."

Black hole cosmology, also known as "Schwarzschild cosmology," suggests that our observable universe might be the interior of a black hole itself within a larger parent universe.

The idea was first introduced by theoretical physicist Raj Kumar Pathria and by mathematician I. J. Good. It presents the idea that the "Schwarzchild radius," better known as the "event horizon," (the boundary from within which nothing can escape a black hole, not even light) is also the horizon of the visible universe.

Black holes are born when the core of a massive star collapses. At its heart is matter with a density that far exceeds anything in the known universe.

In Poplawski's theory, eventually, the coupling between torsion, the twisting and turning of matter, and spin becomes very strong and prevents the matter from compressing indefinitely to a singularity.

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

COMING UP!!

(Saturday, May 3rd, 2025)

"IS THE UNIVERSE IN EMPTY SPACE??"

[mysticstronomy]

GRAVITY MAY NOT BE A FUNDAMENTAL FORCE??

Blog#500

Welcome back,

Saturday, April 26th, 2025

A fresh look at gravity challenges long-held assumptions about one of nature’s most familiar yet puzzling forces. In a new study, two researchers argue that gravitational attraction is not a basic force at all, but an effect that emerges from deeper quantum processes tied to electromagnetism. If confirmed, the theory could help explain mysteries that have long resisted standard models — including the origins of dark matter and the energy accelerating the universe’s expansion.

The work, published in Journal of Physics Communications, reimagines gravity not as a force stitched into the fabric of spacetime, but as something that arises from the quantum-level behavior of ordinary matter. Ruth Kastner of the University of Maryland and Andreas Schlatter at the Quantum Institute in New York developed a framework in which space and time themselves are not fundamental but result from electromagnetic interactions between charged systems like atoms and molecules.

Spacetime from photon exchanges

“The creation of a real photon creates ‘the fabric of spacetime’ by giving rise to spacetime events and their structural connection; namely the emission event, the absorption event, and the real photon which links these,” said Kastner. “In short, spacetime events, along with their structural connections, emerge from these transactions.”

They occur when atoms or molecules emit and absorb photons — the particles of light that carry the electromagnetic force.

According to the theory, each transaction gives rise to a pair of events in spacetime, effectively stitching together a network of relationships that form what we perceive as space and time.

The idea builds on earlier efforts to rethink gravity as an emergent phenomenon — an effect that arises from more basic physical processes, rather than a force on its own. In this picture, the apparent curvature of spacetime described by Einstein’s general relativity is not a fundamental feature of the universe but a large-scale result of underlying interactions between matter and the electromagnetic field.

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

COMING UP!!

(Wednesday, April 30th, 2025)

"IS THE UNIVERSE THE INTERIOR OF A BLACK HOLE??"