The end of the world: Five to seven billion years from now, the Sun will loom in our sky as a blazing 'red giant'.
Credit: Photolibrary
If we could somehow transport ourselves to this distant era, what would we see? "Very little," says Adams. "The universe would be very, very dark, very diffuse." All that will remain is a thin 'soup' of particles "and perhaps other things that we don't know about."
Not much will happen in this rarefied environment, Adams explains. Occasionally, an electron will bind with a positron to form an atom of 'positronium' – but even these will eventually disintegrate. Electrons and positrons can also directly annihilate each other. "Except for these low-level annihilation events," says Adams, "the universe is a very low-energy, low-key kind of place … A sea of darkness."
Perhaps T.S. Eliot was close to the mark in his poem, "The Hollow Men": "This is the way the world ends | Not with a bang but a whimper."
It is hard to think of anything more depressing than this slow decline of the cosmos into eternal darkness. But here goes: because of dark energy's unforgiving push, the night sky of the remote future will be far less rich than the one we see today, and astronomers of that era – if they exist and can exist – will have no inkling of the vast and complex cosmos that once existed.
Our galaxy, the Milky Way, and our closest neighbour, the Andromeda Galaxy, are bound together by gravity; together with a sprinkling of dwarf galaxies, they make up the so-called Local Group. The billions of other galaxies beyond the Local Group are not gravitationally bound to us, and the expansion of the universe, driven by dark energy, will eventually push them out of view. The most distant objects will be the first to disappear – "cloaked behind a cosmological horizon," as Adams puts it. Nearer galaxies will follow, slipping away one by one.
By 100 billion years from now, give or take, even the Virgo cluster – the next-closest cluster of galaxies beyond the Local Group – will have disappeared over the cosmic horizon. We will be then completely isolated from the rest of the universe: beyond the handful of galaxies that make up our Local Group, our telescopes will reveal only blackness. All of those other clusters suffer the same fate; each of them will be similarly isolated from their neighbours. Should astronomers exist in those other realms, their telescopes, too, will reveal nothing.
Our Local Group will still see some action: our galaxy and the Andromeda Galaxy are currently moving toward each other, and they are expected to collide – or rather, merge – in about six billion years. (The merger will not directly affect most stars: stars are very far apart compared to their individual diameters, so a typical star in our galaxy will not undergo a collision with a star from Andromeda.) In the long run, the Milky Way, Andromeda and the other smaller galaxies of the Local Group will merge into one large conglomeration.
When our Local Group becomes a universe unto itself, astronomers will have things to aim their telescopes at locally but will be ignorant of the universe's overall structure. According to Lawrence Krauss of Case Western Reserve University in Ohio, astronomers of this distant era will be hard pressed to infer that anything like a Big Bang had ever occurred.
With those distant galaxies out of view, it will no longer be possible to measure their recession speeds, as U.S. astronomer Edwin Hubble did in the 1920s. The same goes for the other main piece of evidence in support of the Big Bang – the cosmic microwave background radiation (or CMB), sometimes described as 'the echo of the Big Bang', discovered in the 1960s. As the CMB radiation gets stretched out to longer and longer wavelengths, it will be harder and harder to detect.
Krauss has said that astronomers living at that time will be misled by their observations: "It will lead them to the wrong conclusion about what the universe is doing," he said in a recent interview. "The universe will look static, and that's vastly wrong, because the universe is expanding so fast they can't see it."
This is troubling on many levels. It is naturally disheartening to think of knowledge that we have today no longer being available in the remote future; perhaps it will make us strive to preserve that knowledge at all costs. It may also make us wonder just how confident we should be in our interpretations of what we see in the sky right now.
Early Days - End Of Days - Wrong Conclusions
QUOTE:
"Krauss has said that astronomers living at that time will be misled by their observations: "It will lead them to the wrong conclusion about what the universe is doing," he said in a recent interview."
Doesn't the same apply to the science and astronomy of today?
What we are currently observing of the universe might also be incorrect... because of the limitations of light speed we can only "see" up to 13.6 billion years ago, what happened before that we can never truly see... and our assumptions can therefore only be exactly that - assumptions.
All the same, a nice thought provoking article.
So the universe is only a one-time event it seems, much like life on earth, but then a new life (universe) coming into being is still a possibility - it might be very far away from where we are right now, and incredibly far into the future, but a possibility, also just like the birth of early life forms, where the birth of one primitive cell, where it's position and time-line might be so far removed from it's nearest neighbouring cell - that one cell would not know of the existence of the other.
Wonderful stuff, thank you Cosmos Magazine.