Almost 14 billion years ago an incredible event took place. It was a giant explosion where everything began: matter, energy, time and even space itself. Our whole universe came into existence from a single point. What would it be like to live through the end of all that? It depends on whose theory you believe.
In 1950, British astronomer Fred Hoyle dubbed this titanic explosion the Big Bang (largely to make fun of the idea). But this wasn't like an explosion where everything is hurled into space, because there was no space before the Big Bang. Space itself was created right along with matter and time, and it is expanding, too. The result is that everything in the universe is gradually growing further away from everything else.
Another way in which the universe resembles an explosion is that it is becoming cooler as it expands. At the moment of the Big Bang, the temperature of the universe was an incredible 100,000,000,000,000,000,000,000,000,000,000 degrees K (1032 degrees C, 1.832 degrees F). Today, 13.7 billion years later, the average temperature of the universe is a chilly 2.725 degrees K (‑454.761 degrees F, ‑270.425 degrees C).
The End of Everything
What will become of the universe in the distant future? Will it continue to expand and cool? Or will the expansion finally come to a stop? Or perhaps it might start to collapse back onto itself, in the same way that a ball tossed into the air will slow down, stop and then fall back to Earth.
Will the universe then end in a Big Crunch? If this were to happen, the universe would contract and, slowly at first, then faster and faster, the galaxies will come closer together. Eventually, the universe would no longer be large enough for separate galaxies or stars and everything will merge, like snowflakes compressed into a solid snowball. As it shrinks, the temperature of the universe will increase tremendously. Finally, at the end, the universe will exist as it was at the beginning: an infinitely small, infinitely dense, and infinitely hot point.
Will that point eventually explode in another Big Bang, creating a brand-new universe? Have there been other Big Bangs and other universes before our own? Is it a cycle that has gone on infinitely before and will continue infinitely into the future? No one knows.
But most astronomers believe that the universe will keep on expanding. What will happen then? The distances between the galaxies will grow greater and greater. All the galaxies beyond those of our local group will eventually disappear into the unimaginable distance. In our own galaxy, the stars will gradually burn out since there will be nothing left with which to create new ones. The universe around us will slowly grow dimmer and dimmer.
With all of the energy in the universe used up, there will be no stars or planets or galaxies. The temperature will drop to Absolute Zero (‑459.6 degrees F, ‑273.15 degrees C). Molecules and atoms will have no motion. They will simply fall apart, leaving a universe filled with sub-atomic particles. Everything will be at the same temperature and chemical reactions will cease. No work can be done. No information will flow. Even intelligence, thought and imagination will stop. Nothing will ever change. By then, perhaps 1000 billion years in the future, there will be nothing left of the universe but darkness, emptiness and absolute cold. It will be the Big Freeze.
Surviving the Big Freeze?
A few astronomers believe that the Big Bang may not have been a unique event. They suggest that parent universes may give birth to new baby universes. This occurs constantly. If they are correct, new universes are forming even as you read these words. This means that while your universe may come to an end there may be another universe somewhere that is not ending. All that's necessary is to try to figure out some way to travel from one to the other.
These universes exist all around us. We are not aware of them, however. You can imagine our universe as being a like a vast sheet of paper. The other universes are like other sheets of paper. Some lie above ours, some below. We can move around on our sheet all we like. But we can't see the sheets of paper that lie above us, nor the ones below. Even worse, we have no way of jumping off our sheet of paper. If we could do that, we could travel from one universe to another as easily as you can travel from one town to another on Earth.
Some scientists suggest that only a tiny fraction of an inch separates our universe from the next one. But to make that jump would require vast amounts of energy. It would also require technology that doesn't yet exist.
The first thing, of course, would be to try to find out if there even are any other universes. This won't be an easy thing to do. Scientists have devised experiments that would discover the existence of other universes. But these experiments would be among the most delicate ever performed. So far no one has been able to successfully perform one.
But if there are other universes, how could you travel to one? One way might be to use a wormhole. This is a kind of tunnel connecting two universes. Physics allows for the existence of wormholes, but no one has ever yet discovered one. But if natural wormholes aren't found, would it be possible to create one? Certainly. But doing so would require tremendous amounts of energy. To create one the size of a pin hole would require the total energy generated by 10 billion stars in one year. Worse yet, it would require the creation of negative energy. This is a kind of energy that is theoretically possible, and for which evidence exists, but which no one has yet been able to produce. At least not in the gigantic quantities that would be needed to create a large wormhole.
Building a New Universe
Perhaps it wouldn't be necessary to find a new universe if we could simply create a new one from scratch. This might not be as impossible as it sounds.
Baby universes are born when a region of space enters an unstable state called a false vacuum. A false vacuum is created by the gravity generated by super-dense matter. It wouldn't take much matter to do this. Astronomer Alan Guth has calculated that you would need to start with 1089 photons, 1089 electrons, 1089 positrons, 1089 neutrinos, 1089 antineutrinos, 1079 protons and 1079 neutrons. This is only a few ounces. The false vacuum that was needed to create our present universe was very small. It may have been only 4 to 10 inches (10-26 cm) wide. In order to create such a false vacuum from one ounce of matter, the density of the matter would have to be incredible.
Density is a measure of how closely packed a substance's atoms are. The air in a balloon is not very dense because its atoms are spaced far apart. But a bowling ball the same size is very dense because the atoms in it are much closer together. And because a dense object contains more matter than one that is not very dense, it is heavier.
The density needed to create the false vacuum is something like 6.2482 pounds per cubic foot (1080 gm/cm3). That's 624 with eighty zeroes following it—more than six hundred billion, billion, billion, billion, billion, billion, billion, billion, billion, billion, billion, billion, billion pounds of matter crammed into a single cubic foot! (A cubic foot [0.028 m3] of water weighs only 62 pounds [28 kg].) That would be like taking all the matter in the entire universe and compressing it into a cube smaller than a toaster.
Coming up with the few ounces of matter would be no problem. The difficulty would lie in compressing it to such a microscopic volume of space that its density would generate enough false vacuum to trigger the birth of a universe. There is no way anyone can do that today.
But even if we could create a brand-new universe, we would still be faced with the problem of getting into it. Again, we would need a wormhole. And as we've seen, even the tiniest wormhole would require the energy of billions of stars. One large enough for the entire civilization of Earth to pass through would probably require more energy than there is in the universe. But maybe we wouldn't have to do that. Maybe a pinhole is all we would need.
Some scientists have suggested something that might work better than sending humans or spaceships through wormholes. Information doesn't require much space. It can be sent through the smallest imaginable opening. All the information needed to build a human being could turned into a numerical code. In fact, that is what the DNA in your cells is. It is a code that contains all the information that was needed to create you. This information could be placed into a molecule-size robot called a nanobot. Nanobots would then be sent by the millions through the tiny wormhole into the new universe. Each one would carry the DNA codes of thousands or even millions of different people. They would also contain the information needed to create more nanobots.
Eventually, some will land on a moon or planet. They will use the raw materials they find there to create copies of themselves. Eventually there will be billions of nanobots on the planet. They will then begin creating giant biological factories. Using the DNA information that had been recorded in the nanobots, the factories would start recreating human beings. Perhaps in the distant future it might be possible to not only record the DNA codes of individual people, but their memories and personalities, too. These could be implanted in the new bodies. If that were to happen, then the civilization that died along with its universe would be reborn in a brand-new one.