10. Februar 2020

The Big Bang is still on

To a quantum tunneling lifeform that lives 10^50 years from now, our stars are just like the sparkling after the fireworks of the big bang. From their point of view stars lit up for a instant right after nucleons formed and just to give birth to black holes. These black holes are the "stars" for the future quantum tunneling life, which lives on a single Hawking radiation photon every few billion years.
...because Time plays out on a logarithmic scale.

Let me explain:

The universe is about 14 billion years old. And it will be 10.000 times older when the last stars burn out. The universe may look static and dark to us. But it is still in a violent final phase of the big bang. Compared to what follows, the big bang is still going on.
Before stars even formed the universe went through multiple development stages on vastly different timescales. It all started at the earliest observable time, the Planck time, a ridiculously tiny 10 to the minus 43 seconds. At 10 to the minus 36 seconds a process called inflation began to grow the universe very quickly. When inflation ended, the universe had spent 99.9 % of its age inflating. From this point of view, everything before inflation appeared just as an initial flash.
Then for a long time many things happened while the fundamental forces of nature unfolded and the laws of physics as we know them came into being. If someone had observed inflation come and go, then this next phase would have been unimaginably long. A 1000 billion billion billion times longer than inflation had lasted. But finally, quarks condensed into hadrons. Protons and neutrons formed. When that happened, the universe was just a microsecond old.
The universe continued to expand and cool down until electrons and protons could combine to hydrogen atoms. Imagine, you just observed hadron condensation. Then you had to wait another 10 billion billion times longer until hydrogen atoms formed. That's 400.000 years after the birth of the universe. And it is still 3000 K hot. As hot as on the surface of most stars.
Now things happen in quick succession. Only 1000 times longer than everything before, hydrogen atoms clump together and the first stars light up. Stars form galaxies, life appears and hairless apes gaze to the stars. From our point of view, the first stars appeared after only 1% of the age of the universe. 100 times later, now at 13,8 billion years, mighty galaxy clusters are in full swing. The dark matter halo of galaxies sucks in intergalactic hydrogen, galaxies merge, stars explode, supermassive black holes shoot jets over millions of lightyears stirring up the intergalactic medium like the water tap in a bathtub. A wild time.
The universe started out at ridiculously high temperatures. It cooled down a lot. But it is not yet cold. Stars are hot, flooding the universe with radiation, and even without them the universe has a decent background temperature of several degrees. Cold for us, but a lot more than zero.
Radiation is everywhere. We are living in the afterglow of the big bang. With an emphasis on "glow". The universe is still very bright in the microwave range of the electromagnetic spectrum. Our eyes cannot see microwaves, but they are there. The universe is glowing brightly from every direction and countless stars do their part to keep it up.
New stars will be born and die for a long time to come. The smallest live 1000 times longer than our sun. But eventually, the last stars fade. The universe gets dark. That's when the radiation frenzy of the big bang finally ends. The universe will then be 10.000 times older than now. From that point of view, we had been living in the first percent of a percent of the universe. Quarks had condensed into nucleons. Nucleons combined to atoms. Atoms formed stars. Stars kept radiation going. The violent phase of forming and radiating is over when the last stars fade. This is the end of a universe flooded by radiation. A 100 trillion years from now. The end of the radiation epoch. The real end of the fireworks after the big bang.
Times are starting to drag. Nothing happens quickly anymore. No more stars popping in and out of existence. No more flashlights in the dark. No more radiation sources. Only cold planets orbiting black dwarf stars, iron balls, slowly tumbling neutron stars, and black holes in dark galaxies. It's the quiet grown-up phase of the universe. Except for the occasional collision, which sends a blindingly bright spark into the universe.
What does not collide finally spreads evenly. Planets wander off and dark solar systems dissolve. It took a long time until the last star burnt out. And over 100.000 times that duration, galaxies also dissolve thermodynamically. They lose their stars to the void. Iron balls and black holes are still there. But they are now evenly distributed and rarely meet each other. The radiation that was produced in earlier times is also still there. But it is spread out over a vastly larger universe. Photons are so red shifted to ultra-long wavelengths that they are barely noticeable. For all practical purposes, radiation is gone.
The universe is now so dark, that the faint glow of hawking radiation becomes the new standard. Black holes slowly start to evaporate. Hawking radiation of stellar black holes is so weak, that it is not measurable in our bright universe. On the contrary, our times are still so warm that black holes inhale the cosmic microwave background growing a little bit. But then, at the beginning of the end of times, hawking radiation is the only light source. It is weak. If there is any life, then it lives slowly. It will perceive the entire age of stars, a 100 trillion years, like the blink of an eye. On these timescales, a photon every billion years is considered a bright light source. Again, there are flashlights in the dark. But on a totally different scale than the long-forgotten stars.
Even though the universe is huge, black holes still find each other. But between each collision lies a timespan like an entire radiation epoch. Now that counts as the blink of an eye. A hypothetical life form might then be based on ultra-rare quantum tunneling events and it will be living on Hawking radiation. It might see black holes as we now see stars. 
Around the year 1e90, right in the (logarithmic) middle of the black hole epoch (just like where we are living in the log-middle of the stellar epoch), a stellar black hole will give off a radio photon every billion years or an optical photon every million billion years. Considered the perceived time for quantum tunnelling runs 1e65 times slower, they experience a trillion trillion trillion trillion trillion years like we do one second. During this time, a Hawking photon every million billion years amounts to 1e50 photons. For comparison, our sun gives off 1e45 photons per second. That is the same "order" of perceived luminosity, which is just a fancy term for "brightness".
When black holes lose mass this way, they shine even brighter. There will be less luminous large black holes, and smaller ones burning much brighter. For this kind of life form, the universe is filled by shining stellar black holes, glowing supermassive black holes, and brightly burning ageing black holes. Until they explode. These are the supernovae of the future: incredibly bright flashes when black holes explode. They are rare in the neighborhood but they actually happen all the time just like we see supernovae in distant galaxies. Flashes of black hole explosions and collisions will be everywhere, frequent on a timescale where a trillion trillion trillion trillion trillion years feels like a second. 
Remember the long time until dark galaxies dissolved. That was long after all stars went the black hole or iron ball path. It takes a trillion trillion trillion trillion times that again until stellar sized black holes evaporate. That's not "just" a trillion trillion trillion trillion years. It's trillion trillion trillion trillion times all that was before, which already was a billion times longer than our current 13.8 billion years universe. It's a long time, even for ultra-slow quantum tunneling life that lives off a photon every billion years.
Then only real behemoths remain. Giant black holes that dwarf our current supermassive black holes. They have the mass of galaxy superclusters. Fun fact: the event horizon of these ultra massive holes is of galactic dimensions: a million light-years across (not "just" a million kilometers). And they also evaporate. But exponentially slower due to their vast size. It takes another trillion trillion trillion times more.
Eventually there are only ridiculously red-shifted photons left in a ridiculously large universe. The hypothetical quantum tunneling life will be long gone. Our biological way of life is 1 billion years old. It might last 10 billion, maybe even 1000 billion years. The quantum tunneling life may last trillion trillion trillion times longer. It will regard our phase as one of the early stages of the universe. As the last part of the big bang, when the universe was still hot. The black hole era is the real "life" of the universe. Everything before that is just the big bang. An unmeasurably short flash bevor black holes emerged and stayed. And went.
On a logarithmic timescale we live much closer to the begin of everything than to the end. We are now in the first third of the logarithmic timescale. We live on starlight. We think that our time is the real time of the universe and that the big bang was a flash 13.8 billion years ago when nucleon and atom synthesis happened.
The second third of the logarithmic timescale belongs to the hypothetical quantum tunneling life. They live on Hawking radiation from black holes for an unimaginable 10 to the 40 times longer than we did. They think that their time is the real time of the universe and the big bang was just a flash a trillion trillion years ago including a super short stellar phase that gave them their black holes. For them our stars were just a brief intermediate step right after nucleon synthesis, necessary to form black holes, their "stars". 
We don’t know much about the third part of the timescale. Maybe it is just boring for another 10 to the 40 times longer. Maybe there is life so strange and slow, that it regards the earlier – already unimaginable slow – quantum tunneling life as just the blink of an eye. Just a flash before their own real time began. 
Nature finds a way.
And after all that, there are no baryons left and only unimaginably cold photons at wavelengths the size of the universe remain. There are no clocks and nothing that can serve as a measure of time. With time goes distance, both becoming meaningless. So the universe is filled by photons so long, they barely fit into the universe. They may as well be concentrated in a small spot. Who could tell. Basically the size of the universe is just a few wavelengths of the dominating radiation. Maybe then a phase change happens, an implict or explicit rescaling, either just a continuation or a deflation event. Whatever happens then, the result looks very much like all radiation in a small spot by measure of wavelengths. 
The rest is history. Inflation kicks in and the forces of nature unfold creating the laws of physics as we know them - or maybe - this time different ones. 

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