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The Universe is big, as Douglas Adams would say.

The most distant light we can see is the cosmic microwave background (CMB), which has taken more than 13 billion years to reach us. This marks the edge of the observable universe, and while you might think that means the Universe is 26 billion light-years across, thanks to cosmic expansion it is now closer to 46 billion light-years across. By any measure, this is pretty darn big. But most cosmologists think the Universe is much larger than our observable corner of it. That what we can see is a small part of an unimaginably vast, if not infinite creation. However, a new paper argues that the observable universe is mostly all there is.

In other words, on a cosmic scale, the Universe is quite small.

There are several reasons why cosmologists think the Universe is large. One is the distribution of galaxy clusters. If the Universe didn’t extend beyond what we see, the most distant galaxies would feel a gravitational pull toward our region of the cosmos, but not away from us, leading to asymmetrical clustering. Since galaxies cluster at around the same scale throughout the visible universe. In other words, the observable universe is homogenous and isotropic.

A second point is that spacetime is flat. If spacetime weren’t flat, our view of distant galaxies would be distorted, making them appear much larger or smaller than they actually are. Distant galaxies do appear slightly larger due to cosmic expansion, but not in a way that implies an overall curvature to spacetime. Based on the limits of our observations, the flatness of the cosmos implies it is at least 400 times larger than the observable universe.

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Inflation would make the CMB temperature uniform. Credit: Nick Strobel

Then there is the fact that the cosmic microwave background is almost a perfect blackbody. There are small fluctuations in its temperature, but it is much more uniform than it should be. To account for this, astronomers have proposed a period of tremendous expansion just after the Big Bang, known as early cosmic inflation. We have not observed any direct evidence of it, but the model solves so many cosmological problems that it’s widely accepted. If the model is accurate, then the Universe is on the order of 1026 times larger than the observable universe.

So given all of this theoretical and observational evidence, how could anyone argue that the Universe is small? It has to do with string theory and the swamplands.

Although string theory is often presented as a physical theory, it’s actually a collection of mathematical methods. It can be used in the development of complex physical models, but it can also just be mathematics for its own sake. One of the problems with connecting the mathematics of string theory to physical models is that the effects would only be seen in the most extreme situations, and we don’t have enough observational data to rule out various models. However, some string theory models appear much more promising than others. For example, some models are compatible with quantum gravity, and others are not. So often theorists will define a “swampland” of theories that aren’t promising.

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Most of string theory is in the swampland. Credit: APS/Alan Stonebraker

When you separate the promising theoretical lands from the swamp, what you are left with are theories where early cosmic inflation isn’t an option. Most of the inflationary string theory models are in the swampland. This leads one to ask whether you could construct a model cosmology that matches observation without early inflation. Which brings us to this new study.

One way to get around early cosmic inflation is to look at higher-dimensional structures. Classic general relativity relies upon four physical dimensions, three of space and one of time, or 3+1. Mathematically you
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A New Way to Prove if Primordial Black Holes Contribute to Dark Matter

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The early Universe was a strange place. Early in its history—in the first quintillionth of a second—the entire cosmos was nothing more than a stunningly hot plasma. And, according to researchers at the Massachusetts Institute of Technology (MIT), this soup of quarks and gluons was accompanied by the formation of weird little primordial black holes (PHBs). It’s entirely possible that these long-vanished PHBs could have been the root of dark matter.

MIT’s David Kaiser and graduate student Elba Alonso-Monsalve suggest that such early super-charged black holes were very likely a new state of matter that we don’t see in the modern cosmos. “Even though these short-lived, exotic creatures are not around today, they could have affected cosmic history in ways that could show up in subtle signals today,” Kaiser said. “Within the idea that all dark matter could be accounted for by black holes, this gives us new things to look for.” That means a new way to search for the origins of dark matter.

Dark matter is mysterious. No one has directly observed it yet. However, its influence on regular “baryonic” matter is detectable. Scientists have many suggestions for what dark matter could be, but until they can observe it, it’s tough to tell what the stuff is, exactly. Black holes could be likely candidates. But the mass of all the observable ones isn’t enough to account for the amount of dark matter in the cosmos. However, there may be a connection to black holes after all.

Black Holes Through Cosmic Time

Most of us are familiar with the idea of at least two types of black holes: stellar-mass and supermassive. There is also a population of intermediate-mass black holes, which are rare. The stellar-mass objects form when massive stars explode as supernovae and collapse to form black holes. These exist throughout many galaxies. The supermassive ones aggregate many millions of solar masses together. They form “hierarchically” from smaller ones and exist in the hearts of galaxies. The intermediate-mass ones probably form hierarchically as well and could be a hidden link between the other two types.

An image based on a supercomputer simulation of the cosmological environment where primordial gas undergoes the direct collapse to a black hole. Credit: Aaron Smith/TACC/UT-Austin.
An image based on a supercomputer simulation of the cosmological environment where primordial gas undergoes the direct collapse to create black holes. Credit: Aaron Smith/TACC/UT-Austin.

Black holes have formed throughout the history of the Universe. That’s why the idea of primordial black holes isn’t too much of a surprise, although they remain elusive. In their very primitive state, they’d be ultradense objects with the mass of an asteroid punched down into something the size of an atom. They probably didn’t last very long—maybe another quintillionth of a second. After formation, they either blinked out of existence or got scattered across the expanding Universe.

The Link Between Primordial Black Holes and Dark Matter

So, how could these weird PHBs affect the formation of dark matter if they winked in and out of existence so quickly? That’s where Kaiser and his student’s work come in. They suggest that as the first PHBs scattered, they somehow “tugged” on space-time and changed something that could explain dark matter. That same process could have produced even smaller black holes with a curious property called “color charge.” And, there’s a dark matter connection.

“Color charge” is a property of quarks and gluons, and it ends up gluing them together. Think of it as a “super-charge”. Kaiser and Alonso-Monsalve suggest that some of the very early PHBs had this “supercharge” in the same way as the quarks and gluons had it. If that’s true, then the earliest super-color-charged PHBs would have been an entirely new state of matter. We don’t see them around anymore because they likely evaporated a fraction of a second after they spawned. But, their existence was necessary, particularly to the formation of dark matter.

Even

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The Great Red Spot Probably Formed in the Early 1800s

Jupiter GRS and Permanent Spot

Jupiter’s Great Red Spot (GRS) is one of the Solar System’s defining features. It’s a massive storm that astronomers have observed since the 1600s. However, its date of formation and longevity are up for debate. Have we been seeing the same phenomenon all this time?

The GRS is a gigantic anti-cyclonic (rotating counter-clockwise) storm that’s larger than Earth. Its wind speeds exceed 400 km/h (250 mp/h). It’s an icon that humans have been observing since at least the 1800s, possibly earlier. Its history, along with how it formed, is a mystery.

Its earliest observations may have been in 1632 when a German Abbott used his telescope to look at Jupiter. 32 years later, another observer reported seeing the GRS moving from east to west. Then, in 1665, Giovanni Cassini examined Jupiter with a telescope and noted the presence of a storm at the same latitude as the GRS. Cassini and other astronomers observed it continuously until 1713 and he named it the Permanent Spot.

Unfortunately, astronomers lost track of the spot. Nobody saw the GRS for 118 years until astronomer S. Schwabe observed a clear structure, roughly oval and at the same latitude as the GRS. Some think of that observation as the first observation of the current GRS and that the storm formed again at the same latitude. But the details fade the further back in time we look. There are also questions about the earlier storm and its relation to the current GRS.

New research in Geophysical Research Letters combined historical records with computer simulations of the GRS to try to understand this chimerical meteorological phenomenon. Its title is “The Origin of Jupiter’s Great Red Spot,” and the lead author is Agustín Sánchez-Lavega. Sánchez-Lavega is a Professor of Physics at the University of the Basque Country in Bilbao, Spain. He’s also head of the Planetary Sciences Group and the Department of Applied Physics at the University.

“Jupiter’s Great Red Spot (GRS) is the largest and longest-lived known vortex of all solar system planets, but its lifetime is debated, and its formation mechanism remains hidden,” the authors write in their paper.

The researchers started with historical sources dating back to the mid-1600s, just after the telescope was invented. They analyzed the size, structure, and movement of both the PS and the GRS. But that’s not a simple task. “The appearance of the GRS and its Hollow throughout the history of Jupiter observations has been highly variable due to changes in size, albedo and contrast with surrounding clouds,” they write.

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This figure from the research compares the Permanent Spot (PS) and the current GRS. a, b, and c are drawings by Cassini from 1677, 1690, and 1691, respectively. d is a current 2023 image of the GRS. Image Credit: Sánchez-Lavega et al. 2024.

“From the measurements of sizes and movements we deduced that it is highly unlikely that the current GRS was the PS observed by G. D. Cassini. The PS probably disappeared sometime between the mid-18th and 19th centuries, in which case we can say that the longevity of the Red Spot now exceeds 190 years at least,” said lead author Sánchez-Lavega. The GRS was 39,000 km long in 1879 and has shrunk to 14,000 km since then. It’s also become more rounded.

Four views of Jupiter and its GRS. a is a drawing of the Permanent Spot by G. D. Cassini from 19 January 1672. b is a drawing by S. Swabe from 10 May 1851. It shows the GRS area as a clear oval with limits marked by its Hollow (drawn by a red dashed line). c is a Photograph by A. A. Common from 1879. d is a photograph from Observatory Lick with a yellow filter on 14 October 1890. Each image is an astronomical image of Jupiter with south up and east down. Image Credit: Sánchez-Lavega et al. 2024.Did you miss our previous article…
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Fish Could Turn Regolith into Fertile Soil on Mars

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What a wonderful arguably simple solution. Here’s the problem, we travel to Mars but how do we feed ourselves? Sure we can take a load of food with us but for the return trip that’s a lot. If we plan to colonise the red planet we need even more. We have to grow or somehow create food while we are there. The solution is an already wonderfully simple ‘biosphere’ style system; a fish tank! New research suggests fish could be raised in an aquatic system and nutrient rich water can fertilise and grow plants in the regolith! A recent simulation showed vegetables could be grown in regolith fertilised by the fish tank water!

In the next few decades we may well see human beings colonise Mars. The red planet is 54.6 million km away which, even on board a rocket, takes about 7 months to get there! Future colonists could simply have supply ships drop all they need but that becomes ridiculously expensive to sustain and frankly, isn’t sustainable. The lucky people that colonise Mars will just have to find some way to grow what they need.

If you have watched ‘The Martian’ movie with Matt Damon you will know how unforgiving the Martian environment is. Ok the film was a little out on scientific accuracy in places but it certainly showed how inhospitable it really is there. Matt managed to cultivate a decent crop of potatoes in Martian regolith fertilised in human faeces.This may not be quite so practical in real life and there may be alternative, less smelly – and dangerous – alternatives. 

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NASA astronaut, Dr. Mark Watney played by Matt Damon, as he’s stranded on the Red Planet in ‘The Martian’. (Credit: 20th Century Fox)

Taking the assumption that colonists will have to grow fresh produce locally, a team of researchers decided to explore how feasible this might be. On first glance, it may seem not too great an idea after all, the atmosphere is toxic with 95% carbon dioxide (compared to just 0.04% on Earth). There is a similar length of day on Mars but being able to grow crops will require longer periods of lighting. It is possible at least water may be collected from the ice which forms on and in the Martian rocks. The rocks most certainly have water stored away but organic compounds that we know of.

The team wanted to see how fish could help and whether the water from the system could be used to impart nutrients into the Martian regolith. To test the idea, they setup an aquaponic system with fish in tanks to generate the nutrient rich liquid.

The results were very promising. They found that aquaponic systems not only facilitate growing plants within the system itself but the nutrient rich water performed as an excellent fertiliser. This took the organically deficient regolith and turned it into something akin to useable soil. The fish used in the study were tilapia (Oreochromis niloticus) and using them, the team managed to grow potatoes, tomatoes, beans, carrots and much more. To enable all this to happen, the fish received sufficient light and other environmental stimulus. The plants were grown and indeed thrived in a tent that simulated Mars in every way possible.

It’s an interesting aside that the study not only benefits future space travellers but those inhabitants of more environmentally hostile places on Earth.

Source : Fish and chips on Mars: our research shows how colonists could produce their own food

The post Fish Could Turn Regolith into Fertile Soil on Mars appeared first on Universe Today.

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