What is the universe made of? Some things seem to exist and persist outside of our imaginations. We don’t really know what this real stuff is, but we have made-up names for particles and forces. We can predict things about them, sure, but we don’t know what they are. They just are.
We still have no idea why the speed of light is the particular speed it is. Even more amazing, most of the universe appears to be made of stuff that is completely foreign and mysterious to us, things we have never directly observed on our small planet: dark matter and dark energy. If you can hold this picture of the mysterious universe and stay in a state of appropriate awe for long enough, perhaps imagination and/or intuition will give you a clue to something great that you never dreamed was possible.
That’s what I think when I occasionally try to review the big picture.
Over the last few decades, scientists have come to the conclusion that the universe’s composition is only about 5% atoms — in other words, the stuff that we see and know around us. That means the rest is stuff we can’t see. About 71% is something called “dark energy,” and another 24% is “dark matter.”
Research is ongoing to figure out precisely what these “dark” components are, because they do not interact with ordinary matter and have never been directly detected. But the large-scale structure of the universe depends on dark matter. “Without the dark matter, all the stars would fly away,” said Adam Riess, physicist at Johns Hopkins University and the Space Telescope Science Institute. Dark energy is thought to be responsible for the accelerating expansion of the universe, and Riess’s Nobel-prize winning work supports this theory. In principle, these phenomena are everywhere — but how can we find them? …
… Brian Greene, theoretical physicist at Columbia University and “NOVA” host, describes it this way:
“You can think of it as a kind of molasses-like bath that’s invisible, but yet we’re all immersed within it,” he said. “And as particles like electrons try to move through the molasses-like bath, they experience a resistance. And that resistance is what we, in our big everyday world, think of as the mass of the electron.”
Without this “substance,” made up of Higgs particles, the electron would have no mass, and we would not be here at all. …
“If you want to understand the big, you have to understand the small,” Primack said. …
Models of the force required to explain the universe’s accelerating expansion rate suggest that dark energy must make up between 70% and 75% of the universe. Dark matter, meanwhile, accounts for about 20% to 25%, while so-called ordinary matter — the stuff we can actually see — is estimated to make up less than 5% of the universe, Bahcall said.
Assuming that the concordance model of cosmology is correct, the best current measurements indicate that dark energy contributes 68% of the total energy in the present-day observable universe. The mass–energy of dark matter and ordinary (baryonic) matter contribute 27% and 5%, respectively, and other components such as neutrinos and photons contribute a very small amount.
Dark energy is thought to be very homogeneous and not very dense, and is not known to interact through any of the fundamental forces other than gravity. Since it is quite rarefied and un-massive—roughly 10−27 kg/m3—it is unlikely to be detectable in laboratory experiments. The reason dark energy can have such a profound effect on the universe, making up 68% of universal density in spite of being so dilute, is that it uniformly fills otherwise empty space.
Independently of its actual nature, dark energy would need to have a strong negative pressure (repulsive action), like radiation pressure in a metamaterial, to explain the observed acceleration of the expansion of the universe.
The universe is made up of microscopic black holes and white holes that are constantly popping in and out of existence. One source says tiny black holes can’t be created now, but what do we know?
Tiny in this context means something around a billionth of a billionth of the mass of the sun—a couple billion tons, or the mass of a small asteroid. A black hole of this mass would be about the size of an atomic nucleus. Physicists have speculated that, when the universe was very young and hot, copious numbers of miniature black holes may have been produced. (PBS)
What would happen if a micro black hole hit the earth? Depending on the size, nothing or not much.
The small radius and high density of the black hole would allow it to pass straight through any object consisting of normal atoms, interacting with only few of its atoms while doing so. It has, however, been suggested that a small black hole (of sufficient mass) passing through the Earth would produce a detectable acoustic or seismic signal. (Wikipedia)
These tiny black holes, and all black holes really, should also eventually vanish.
Stephen Hawking famously discovered that black holes can lose mass by emitting elementary particles. … “Hawking radiation” should cause a black hole to shrink and eventually evaporate.
What happens when a black hole of any size vanishes? This process may generate dark matter in the form of white holes. What can we guess about white holes?
In the 2014 study, Rovelli and his team suggested that, once a black hole evaporated to a degree where it could not shrink any further because space-time could not be squeezed into anything smaller, the dying black hole would then rebound to form a white hole. …
The local density of dark matter, as suggested by the motion of stars near the sun, is about 1 percent the mass of the sun per cubic parsec, which is about 34.7 cubic light-years. To account for this density with white holes, the scientists calculated that one tiny white hole — much smaller than a proton and about a millionth of a gram, which is equal to about the mass of “half an inch of a human hair,” Rovelli said — is needed per 2,400 cubic miles (10,000 cubic kilometers).
These white holes would not emit any radiation, and because they are far smaller than a wavelength of light, they would be invisible. If a proton did happen to impact one of these white holes, the white hole “would simply bounce away,” Rovelli said. “They cannot swallow anything.” If a black hole were to encounter one of these white holes, the result would be a single larger black hole, he added. As if the idea of invisible, microscopic white holes from the dawn of time were not wild enough, Rovelli and Vidotto further suggested that some white holes in this universe might actually predate the Big Bang.
Interesting, isn’t it?
There are so many unanswered fundamental questions. How does anyone get anything done?
For one, we forget to stay sane. Every night, although we may not remember it, we dream, during which time our amazing brains shrink, this is a good thing. Then fluid comes in and cleans up and flushes out toxins after an active forgetting process that gets rid of excess information to prevent overload. Dreaming seems to be the effect of this clean up as the process decides what to forget and what to store in long term memory.
Get enough sleep every night. That’s a goal. Seven and a half hours seems to be ideal from the research. I remember that. Looking up why, I see that we need to get five full cycles of brain cleaning done each night.
… most people go through five 90-minute sleep cycles per night, Breus says. That’s why the average person needs 7.5 hours of sleep. Five cycles of 90 minutes each works out to be 450 minutes in total, which is the equivalent of 7.5 hours. (Insider)
That’s 5 cycles of dreaming as well since we dream about every 90 minutes. We also daydream in 90 minute cycles, our left and right brain hemispheres take turns in 90 minute cycles being dominant and the side of our nose that we are breathing from changes with the brain hemisphere dominance cycle as well.
Did you know this?
So many fascinating things to know … and to be forgotten.