Paul Davis, PHYSICIST: It’s the end of the world

2022-07-04 0 By

Tiger year reading, like a tiger with wings added.From the second day of the Chinese New Year to the tenth day of the Chinese New Year, Mr. Zhan Lu will solemnly introduce to you the “Master of Science” series of Mr. Zhan Lu.Today let’s open a book called The Last Three Minutes of the Universe by Paul Davies.Paul Davies, professor of physics at the University of Adelaide, Australia, is a world-renowned physicist and a master of explaining abstruse scientific concepts in concise and vivid language.His research includes black holes, quantum field theory, the origin of the universe, the nature of consciousness and the origin of life.In the Last Three Minutes of the Universe, Davis takes us on a quest to find out how the universe will end: Will it?How will the human race survive and exist forever?We hope that superhumans or supercomputers in the universe will at least learn enough about their own existence in the time available to them to accept their inevitable demise.For a long time after 100 billion years, astronomers will not notice that the universe is collapsing.The first thing they would notice is that, on average, relatively nearby galaxies are getting closer rather than receding, but the spectra from distant galaxies still seem to be redshifted.Only after tens of billions of years will a systematic influx become apparent.What’s easier to identify at this point are subtle changes in the temperature of the COSMIC microwave background.It should be remembered that the COSMIC microwave background is a relic of the Big Bang and is currently about 3 kelvin above absolute zero.As the universe expands, that temperature drops.After 100 billion years, it will fall to about 1 Kelvin.The temperature will drop to its lowest point at the peak of the expansion, then rise again once the collapse begins, and by the time the universe has collapsed to today’s density, the temperature will have returned to 3 Kelvin, which will take another 100 billion years — the universe rises and falls roughly symmetrically in time.The universe did not collapse overnight.For tens of billions of years, even in a contracting phase, our offspring were able to get along just fine.If the tipping point takes place in a much longer time, say, a trillion years, the picture is not so rosy.In this case, all the stars would burn up before the expansion reached its peak, and any surviving inhabitants of Earth would face the same problems they would face in an eternally expanding universe.If measured in years from now, the universe will return to its current size in the same number of years, no matter when that transition occurs.But it will look very different.Even if the transition does occur 100 billion years from now, there will be more black holes, fewer stars and habitable planets at a premium than there are now.When the universe collapses to its current size, it will collapse at an even faster rate, and in about 3.5 billion years, the size of the universe will be halved and the acceleration will be smaller.The real crunch will come after 10 billion years, when the rising temperature of the COSMIC microwave background becomes a serious threat.When temperatures rise to about 300 kelvin, planets like Earth have a hard time losing heat.It will get hotter and hotter, and there is no turning back.Any ice caps or glaciers will melt and the oceans will start to evaporate.2 In the final moments, gravity becomes the dominant force, ruthlessly smashing matter and space.The curvature of space-time is increasing.Larger and larger areas of space are compressed into smaller and smaller volumes.In 40 million years, the CMB will reach the average temperature of the Earth today.Planets like Earth would have been completely inhospitable.When the sun swells into a red giant, earth will face the same fate.Our children will have nowhere else to go.The cosmic microwave background radiation fills the entire universe, and the temperature of space is 300 kelvin and rising.Scientists who have adapted to such hot conditions, or who have created a cooling ecosystem to stave off the threat of being “cooked”, will note that the universe is collapsing rapidly, shrinking by half every few million years.Any galaxies that still exist will be unrecognizable because they are one.However, the universe is still very big, and collisions between individual stars are still very unlikely.As the universe nears its final phase, it will be in a state increasingly similar to that seen shortly after the Big Bang.Astronomer Martin Rees studied collapsing universes.By applying general physics principles, he built up a picture of the final collapse of the universe.Eventually, the CMB will become so intense that the night sky will appear as a dark red glow.The universe will slowly become an all-encompassing melting pot, roasting all fragile life forms wherever they hide, long after the planets’ atmospheres have been stripped clean.Gradually, the red light turns yellow, then white, until the intense thermal radiation that fills the universe threatens the existence of the star itself.Unable to radiate energy, stars gather heat inside and explode.The universe is now filled with hot gas plasma, which is burning fiercely all the time, getting hotter and hotter.As the pace of change quickens, the situation becomes more extreme.It would only take 100,000 years for the universe to begin to change significantly, then 1,000 years, then 100 years, accelerating towards disaster, with temperatures rising to millions of Kelvin, billions of Kelvin, and the matter occupying the vast expanse of space being compressed infinitely,The mass of a galaxy occupies a space only a few light years across — the last three minutes of the universe have arrived.The universe eventually became extremely hot, and atomic nuclei disintegrated, stripping matter into a uniform soup of elementary particles.The Big Bang and the heavy elements created by destroying generations of stars have taken less time than it takes you or me to read this page.Nuclear structures that have been stable for trillions of years will be completely destroyed.All structures except black holes are long gone.The universe now exhibits an elegant but sinister resemblance, but only for a few seconds.As it collapses faster and faster, the temperature rises, and it rises faster and faster.Matter is so compressed that individual protons and neutrons no longer exist, leaving only a quark soup.The collapse will continue to accelerate, and it will be microseconds before the ultimate cosmic catastrophe.The black holes began to merge with each other, and their interiors were almost indistinguishable from the general collapsed state of the universe itself.They are now just a few regions of space-time that have reached the end ahead of schedule and are connecting with the rest of the universe.In the final moments, gravity becomes the dominant force, ruthlessly shattering matter and space.The curvature of space-time is increasing.Larger and larger areas of space are compressed into smaller and smaller volumes.According to conventional theory, implosion would become so powerful at the singularity that it would shatter everything, including space and time itself.This is the end of the world.This is from The Last Three Minutes of the Universe.