Thursday, January 5, 2023

What happened to the universe in 2022

Planet Earth is not the only one that undergoes significant changes during the year. During this period, the universe itself undergoes subtle variations that, when accumulated over the years, impose more drastic alterations.

On our planet, some things happen during 12 months — the passage of four seasonal weather seasons means a series of cycles, such as the increase / decrease in the population of some species, different stages of water cycles, among many others.

In the universe, during this same time, the changes are much less noticeable, but that does not mean that they are small. In fact, we don't notice them due to cosmic distances and astronomical ratios of sizes, masses and densities.

 Our star, for example, which by astronomical standards is right next to us, is 149,600,000 km away from Earth — something unimaginable for us humans, because we have never experienced it here on Earth. Still, it's next to nothing on a cosmic scale.

 Due to the proportions of the universe, changes that are very large for our perception may actually be insignificant in relation to the whole. For example, our Sun, due to internal nuclear reactions, loses about 1017 kilograms of mass per year. That's a lot for our conception, but equivalent to just a sneeze for our star.

Even so, these “sneezes” have long-term consequences: as our star loses mass, its gravitational power decreases. So Earth spirals outward , increasing our orbital radius by 1.5 cm every year.

Other curious subtle changes with important implications for the future: gravitational interactions slow down our planet's rotation, making days 14 microseconds longer each year. In this same period, the Moon-Earth distance increases by 3.8 cm.

The consequences are interesting and sometimes require small tweaks to our technologies. For example, days gaining a few microseconds may require occasional additions of seconds to our clocks.

As 12 months pass on our planet, the Sun gets hotter, becoming 0.0000005% brighter; about 5 new low-mass stars form in the Milky Way; 50 million supernovae explode across the universe and the cosmic microwave background radiation (the “fossil” light from the Big Bang) becomes 200 picokelvins cooler.

 In the entire observable universe, stars formed in the span of a year add up to a total of 45 billion solar masses. Due to the expansion of the universe, the observational boundary has increased by 60 trillion km (or 6.5 light-years) in 2022. It also increases the perceptible boundary by about 35,000 every year.

That's not to mention more mysterious events like fast radio bursts, the formation of new black holes, collisions between massive objects like neutron stars — all of which are important to our universe's cycles of energy and matter transformations.

Just as our planet is constantly changing year after year, the universe itself is always evolving, becoming ever more chaotic and complex due to entropy. Each terrestrial year is one more grain of sand flowing through the hourglass of the universe, which is heading towards an inevitable end - or a new beginning.

Source: Stars With a Bang

1_ As the Sun produces energy via nuclear fusion, its mass decreases; the phenomenon is explained by the formula E=mc², by Albert Einstein (Image: Reproduction/Wikimedia Commons/KelvinSong

2_ The cosmic background radiation is the light emitted shortly after the Big Bang, at high temperature. From our perspective, after 13 billion years, the temperature is only 2.725 K above absolute zero. Each year, light cools down further by about 0.2 nanokelvin (Image: Playback/NASA/BlueEarth/ESO/S. Brunier/NASA/WMAP) 

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