FOUND: the Universe’s Missing Matter

There are two kinds of matter in the universe. There is dark matter, which is invisible to us. It is known only because of its gravitational effects on a grand scale. And there is ordinary matter, which we are all familiar with; it makes up gases, dust, stars, planets, and earthly things like cake batter and camping gear.

Scientists have estimated that ordinary matter makes up only 15% of all matter. But they have struggled to document where all of the matter is located, since only about half of it is accounted for. Now, with the help of powerful bursts of radio waves emanating from 69 locations in the cosmos, researchers have found the “missing” matter.

It was primarily hiding as thinly distributed gas spread out in the vast expanses between galaxies and was detected because of the effect the matter has on the radio waves traveling through space. This tenuous gas is the intergalactic medium, a sort of fog between galaxies.

Scientists had previously determined the total amount of ordinary matter using a calculation involving light observed that was left over from the Big Bang. But they could not actually find half of this matter.

Researchers found that a smaller slice of the missing matter resides in the halos of diffuse material surrounding galaxies, including our Milky Way.

Ordinary matter is composed of baryons, which are the subatomic particles needed by protons and neutrons to build atoms. Dark matter, on the other hand, is a mysterious substance. Scientists do not know what new particle or substance makes up dark matter.

How did so much ordinary matter end up in the middle of nowhere? Vast amounts of gas are ejected from galaxies when massive stars explode as supernovas of when supermassive black holes inside galaxies “burp,” expelling material after consuming stars or gas.

If the universe were a more boring place, or the laws of physics were different, ordinary matter would all fall into galaxies, cool down and form stars until every proton and neutron were a part of a star.

Thus, these violent processes throw ordinary matter across immense distances and consign it to the cosmic wilderness. This gas is not in its usual state; it is in the form of plasma, with its electrons and protons separated.

The missing ordinary matter was detected and measured by using phenomena called fast radio bursts, or FRBs. These are powerful pulses of radio waves emanating from faraway points in the universe. Their exact cause remains mysterious, but a leading hypothesis is that they are produced by highly magnetized neutron stars, which are compact stellar embers left over after a massive star dies in a supernova explosion.

As light in the radio wave frequencies travels from the source to Earth, it becomes dispersed into different wavelengths, just like a prism turns sunlight into a rainbow. The degree of dispersion depends on how much matter is in the light’s path. This provides the mechanism for pinpointing and measuring matter where it otherwise would remain unfound.

Scientists used radio waves traveling from 69 FRBs. Of these, 39 were discovered using a network of 110 telescopes located at Caltech’s Owens Valley Radio Observatory near Bishop, California, which is called the Deep Synoptic Array. The remaining 30 FRBs were discovered using other telescopes.

The FRBs were located at distances up to 9.1 billion light-years from Earth, which is the farthest of these on record. A light-year is the distance light travels in a year (5.9 trillion miles/9.5 trillion km).

With all the ordinary matter accounted for, researchers were able to determine its distribution. About 76% resides in intergalactic space, approximately 15% in galaxy halos, with the remaining 9% concentrated within galaxies as stars or gas.

Now they can move on to other mysteries regarding ordinary matter. And beyond that, they still don’t know the nature of dark matter.

 

https://www.msn.com/en-us/news/technology/astronomers-locate-universe-s-missing-matter/ar-AA1GPaMp?ocid=hpmsn&cvid=c615a1d5e8e948159c93cc31030732f0&ei=41

Mercury

 I’m sure we all remember Mercury from our school days. It’s the closest planet to the sun, traveling around our local star once every 88 days. Now, I learned—way back when—that Mercury was tidally locked to the sun, meaning that one side was always facing the sun, while the opposite side was forever dark. But such is not the case. It turns out that Mercury spins completely around roughly every 59 Earth days. But because it is also moving around the sun, a day/night cycle is about 176 days long. So it has long days, and short years.

It is the smallest planet of our system... except for the dwarf planets. It is slightly larger than Earth’s moon at 9,525.1 miles around its equator. By the way, Mercury has no tilt to it, so it has no seasons except whatever small differences might occur because its orbit is elliptical and not round. The gravity at its surface is roughly 3/8 that of Earth. So a person weighing 100 pounds on Earth would weigh about 37.5 pounds on Mercury.

Like all the ‘inner’ planets, Mercury is a rocky planet. It’s surface is quite cratered, much like our moon.

It is only 39 million miles from the sun. If you were standing on Mercury, the sun would look 3 times larger than it does on Earth. It would also feel 7 times hotter. The daylight temperature can climb to 800 degrees Fahrenheit. At night, that temperature would plummet to -290 degrees Fahrenheit. Therefore, it is not likely that life as we know it would be able to exist there.

That is particularly true because of the atmosphere, what there is of it. It consists of oxygen, sodium, hydrogen, helium and potassium. These are atoms that are thrown up by blasts of the solar winds as well as micrometeor strikes.

The article stated quite bluntly that Mercury has no moons. How lonely it must be. I also wonder, what if it does? In that case, it would need to be very small, or it would have been found by now. But what if there were a pea-sized moon zipping around Mercury? And let’s suppose we eventually sent a manned mission there, to land on the dark side (since the light side is so hot) to bring back Mercury samples. How many spacemen would be killed by that moon zipping through their space suit (and maybe them) before they figured out what was happening? Or would punching through their space suit slow it down enough that it would fall to Mercury’s surface, and they might never figure it out?

Well, I’d have to stop and figure out the physics. And I’m not sure where my physics book is anymore.

 

https://solarsystem.nasa.gov/planets/mercury