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Dark Matter: The Dark Mystery
By Shlomo Maital
Think about it. There could be an entire cosmos, universe, co-existing with our own, but – entirely invisible to us, because its own laws of nature are utterly different from ours, and the stuff it is made of does not interact in any way with the stuff WE are made of.
This is not science fiction. It comes from a leading theoretical physicist at Cal Tech (California Institute of Technology, in Pasadena), Kathryn M. Zurek, writing in The Economist (March 18).
Here is an excerpt: “.dark matter might not be one particular particle – it may be a whole hidden sector of dark particles and forces. In this dark sector, particles would interact through their own independent forces and dynamics, creating a hidden world of cosmology running parallel to our own. There could be dark atoms…held together by dark electromagnetism. [there might be] huge dark atomic nuclei…helping form supermassive black holes in the centers of galaxies. [Note: There is such a huge black hole in the center of our galazy, the Milky Way].”
Professor Zurek concludes: “The fundamental nature of the dark matter that pervades our universe is still unresolved.”
Conclusion: We don’t really know what the universe, i.e. we, the people, is made of. We know 5%. One in twenty. 70% is dark energy. 25% is dark matter. So our ignorance embraces 95% of our universe.
So – I am an economist. We claim to know everything, while knowing basically zero.
The physicists happily, gleefully, joyfully, admit to knowing almost nothing.
If I were starting college again, I would probably become a physicist. It is better to know some of the key questions, James Thurber wrote, than to pretend you know all the answers.
Dark Matter Is Changing & Evolving
By Shlomo Maital
What do we know about our 13.8-billion-year-old universe? A lot – and very little.
We know that 5 per cent of it is comprised of atomic matter – particles. They interact with us, and we can see them, study them, smash them to pieces and examine what comes out. 25 per cent is dark matter – matter that we cannot see, that does not interact with other particles and is invisible. 70 per cent is dark energy – energy that also does not interact with existing matter and so is invisible.
Conclusion: 95% of the universe is a total dark mystery to us. We know this, because if the universe comprised only the matter we observe, its rate of expansion should be slowing as cosmic bodies grow more and more distant from one another and gravity weakens.
Instead, we observed that the universe is expanding – at a faster and faster rate! Only dark matter and dark energy can explain this.
Projecting dozens and hundreds of billions of years into the future, at the current rate the universe goes dark – because objects become too far apart for us to see, and the sun has long ago gone dark, using up its helium.
But wait! There is new evidence, from DESI, dark energy spectroscopic instrument, atop an observatory in Arizona’s desert. Dark energy, it was found, is evolving, changing. It is not constant. So, we could well NOT have the cosmos go dark, but rather, stop expanding, and collapse inward, implode – and cause a new Big Bang.
I envy the physicists. They have the world’s biggest mystery to solve — and I sense their energy and joy at not yet knowing in the least what the universe really is and how it works.
And we humans? Who think we know everything? Not even close.
Rethinking Dark Matter & Dark Energy
By Shlomo Maital
Adam Riess is a Johns Hopkins U. professor of astrophysics and 2011 Nobel Laureate. His research showed that the universe is expanding (Hubble found that years ago), at an increasing rate – which defies the standard laws of gravity, that suggest that as cosmic bodies grow more distant, the force of gravity weakens. This means that there is unobserved dark matter and dark energy out there, which does not interact with conventional matter and energy, and it must be some 95% of existing energy and matter (63% dark energy, 32 percent dark energy).
Riess is part of a team researching the cosmos using the DESI, dark energy spectroscopic instrument. It is located in the Sonora Desert, atop Kitt Peak, in Arizona. It is creating a 3D map of the positions and velocities of 40 million galaxies across 11 billion years of time. The first map just released covers six million galaxies. The director of DESI, Michael Levi, said that “we’re seeing some potentially interesting differences that could indicate that dark energy is evolving with time’.
Riess said about the results that “it may be the first real clue we have gotten about the nature of dark energy in 25 years!”. His words were reported by Dennis Overbye, in the New York Times. Overby covers astrophysics and brilliantly explains complex subjects in a lucid understandable manner.
If the current standard model is true, then the universe will grow darker and darker, as cosmic bodies grow more distant one from another – and eventually, even atoms will rip apart and everything will disintegrate, billions of years from now. But if dark matter and dark energy are evolving, changing in a dynamic manner, well – maybe not.
Perhaps one day, we will actually find a way to observe and understand dark matter and dark energy.
Meanwhile, it is exhilarating to see how astrophysicists are eager and willing to admit that what they thought they knew is not the case. Would that all of us would be so wise.
The End of Everything – But…Not For Several Billion Years!
By Shlomo Maital
Katie Mack, North Carolina State U
For many, the current pandemic does seem like the end of the world, at least as we know it. In both Israel and the US, a distressingly high proportion of people suffer from some form of post-trauma.
It is not the end of the world, of course — but it is still interesting to read what an expert, a cosmologist, thinks about the universe, of which our world is a tiny part, will end someday. Prof. Katie Mack has written a fine book about, The End of Everything (Scribner, 2020). She was interviewed on Ira Flatow’s fine podcast Science Friday (NPR).
So here are a few ways the universe will end. In several billion years.
- Expand into nothingness: We now know the universe is expanding outward, faster and faster, thanks to ‘dark energy’ (an energy source which we do not understand…yet). [“Wendy Freedman determined space to expand, so that for every 3.3 million light years further away from the earth you are, matter is moving away from earth 72 kilometers a second faster.] If it continues to expand forever…then in billions of years, the universe will expand into….nothingness.
- Implode into a new Big Bang. Some 13.6 billion years ago, the universe imploded into a tiny space smaller than an atom, much smaller: and then exploded, becoming the Big Bang. This could happen again. At some point, the universe may stop expanding, we’re not sure why or how – and then stop expanding, and start contracting, moving inward…and…. Wham, another Big Bang. Perhaps there has been an infinite number of such Big Bangs….explosion, implosion…. Etc.
- A voracious bubble: We do not understand why, in the Big Bang, there was not the creation of equal amounts of matter and anti-matter. (There is far far more matter than anti-matter – e.g. an electron is ‘matter’, a positron, with a plus charge, is anti-matter. And there are huge amounts of dark matter, matter we cannot see or explain, because otherwise the forces of gravity cannot be explained). The laws of physics are thus violated. Somewhere there may be a ‘Hungry Bubble’ – a tiny place in the universe where the laws of physics are different… and this bubble may begin swallowing matter, sucking matter into the bubble and destroying it….
In this pandemic, humankind has learned a great deal of humility. We have been defeated so far by a few strands of RNA. Another dose of humility comes from cosmology. We humans on Planet Earth are just the tiniest of inconsequential specks, in this enormous universe, which grows larger and larger every second, as it expands. Life on Earth (if any remains) will end when our sun explodes in a few billion years. And long long after that, as Katie Mack shows, the entire universe will end…
…but we don’t know how.
And: a small excerpt from one of the many sterling reviews:
“ Astrophysicist Katie Mack provides insight into the myriad ways in which the world could end, extinguishing life in the process, and despite the topic being a morbid and sobering one I found it absolutely riveting, extensively researched and accessible throughout; it really is a rarity that a science book can have you so enthralled by what you are reading. It explores five different ways the universe could end and the wondrous physics, big questions, and mind-blowing lessons underlying them with each being discussed thoroughly and all being deeply interesting concepts to read about, if not a little scary.”
TIMnovate 