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Only 8% of the Universe's Habitable Worlds Have Formed So Far (sciencemag.org)
sciencehabit writes: According to a new study, 92% of Earth-like planets haven't been born yet. Science reports: "Using data from the Hubble Space Telescope, researchers estimated the rates of past star and planet formation in the universe, which is now about 13.8 billion years old. They then combined that information with data from previous surveys that estimated the amounts of hydrogen and helium left over from the big bang that still haven't collapsed to form stars. At the time our solar system formed about 4.6 billion years ago, only about 39% of the hydrogen and helium in our galaxy had collapsed into clouds that then evolved into stars, they say. That means that the remaining 61% is available to form future solar systems that may include Earth-like planets in their habitable zones, the researchers report online today in Monthly Notices of the Royal Astronomical Society. In the universe as a whole, the researchers suggest, only 8% of its original starmaking gases was locked up in stars by Earth's first birthday. The rest will, over the remaining trillions of years of the universe's lifetime, coalesce into stars whose solar systems will contain a myriad of Earth-like planets."
There is only so much gas that will become stars, most of it will forever float in the space between galaxies. The timeline is 100Gyr-1Tyr.
NB: The message above might reflect my opinion right now, but not necessarily tomorrow or next year.
At that time the Universe was mostly Hydrogen and a little Helium. It took the death of 1-2 generations of stars to make Oxygen available to planets -- so no water.
NB: The message above might reflect my opinion right now, but not necessarily tomorrow or next year.
You may want to reread up on the Heat Death of the Universe. Our Sun won't even be cold in 5 billion years, never mind the rest of universe. Existing red dwarf stars may last a 100 billion years. Most models put the Stelliferous Era (era of stars) as extending 10s of trillions to 100s of trillions of years into the future. True Heat Death is 10E100 or 10E1000 years out depending on the model, but there won't be any stars or planets (protons will have decayed). Although the Big Rip may occur in as little as 20 Billion years
Both. Actually it's been happening since day 1 of the Universe. Even now everything is getting further and further away from, well... everything else (on average) (https://en.wikipedia.org/wiki/Hubble%27s_law). Space between galaxies, systems, planets and atoms expands and the Universe is getting cooler (on average, there might be spots when locally it gets hotter but as a whole it gets cooler). So first everything will run out of energy and then it will diffuse into atoms and eventually even atoms will break apart.
Black holes radiate energy too and those will evaporate at some point in time too (it may take trillions of years or more but eventually it will happen). (https://en.wikipedia.org/wiki/Hawking_radiation)
At least that's one of current theories. We really don't know what will happen in billion or trillion years. Universe is strange and it might turn out that our models of physics (I always cringe when someone speaks of "laws of physics") don' capture vast majority of what's happening in it.