This article lists what it calls 17 ‘outstanding’ scientific mysteries that have currently eluded researchers’ ability to solve. Any such list is always subject to criticism about its choices and one could quibble with what is included and what has been left out. But it is useful as a discussion starter. I question the use of the word ‘mysteries’ for most of them because that implies questions that we have little or no idea how to address. These questions are what I would call ‘puzzles’, in that we do know how to tackle them even if we have not achieved success as yet.
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But the questions are undoubtedly interesting and of those, two in particular caught my attention because I wrote about them in my book The Great Paradox of Science. They are: What is the universe made of? Was there an advanced civilization on Earth before humans?
What is the universe made out of?
This one is about how the search for dark matter is proving to be so elusive. In chapter 17 of my book I suggested that we may be in the midst of a crisis that precedes a paradigm shift (using the model proposed by Thomas Kuhn), similar to what happened with the ether back at the dawn of the twentieth century. At that time, the existence of the ether was strongly believed even though it had not been directly detected. Various explanations were given to explain away the negative results but they became increasingly strained and it would be fair to call the situation a crisis. The time was ripe for a change and when Einstein proposes his special theory of relativity, although it did not disprove the existence of ether (something I argue cannot be done), it did make it redundant. Since it was no longer needed as an explanatory concept, and special relativity proved to be a fruitful source of new research it was possible to deem the ether to be non-existent and embrace relativity, which is what happened.
Something similar is happening with dark matter. In my book, I wrote:
The current status of dark matter is similar to that of the early days of neutrinos. The existence of those earlier particles had been postulated to explain why some observed nuclear reactions seemed to violate the laws of conservation of energy and angular momentum. Arguments for the existence of that hitherto unknown particle competed with theories that suggested that the conservation laws needed to be modified for these reactions. Over time, the indirect evidence for the existence of neutrinos was strong enough that, combined with reluctance to abandon the conservation laws, they were given provisional status of existence. But the neutrino theory did not merely explain existing anomalies. It also predicted, as all good scientific theories do, results of specific reactions that experimenters could investigate and the testing of these predictions eventually led a quarter century later to direct positive evidence of their existence, shifting their status from provisional to confirmed.
Dark matter has similarly become an explanatory concept for various stellar phenomena involving galaxies and clusters of galaxies that seem otherwise inexplicable. Some observations of the cosmic microwave background radiation also seem to support the idea of dark matter (Ade et al. 2016). The case for its existence has become sufficiently strong that although we do not know many of its specific features, it has been granted provisional existence status pending direct observation.
…While the direct detection of either dark matter or dark energy will swing the argument for existence decisively in its favor, the failure of current searches would not imply that they do not exist because of the eternal problem of establishing a negative. Like the aether, they will only cease to “exist” if, in addition to not being directly detected, alternative theories come along that make them unnecessary as explanatory concepts, and these alternative theories also develop a preponderance of positive evidence in their favor. This is how, as was discussed earlier, the theories of special and general relativity eliminated the aether and the planet Vulcan, and the oxygen theory of combustion got rid of phlogiston.
As efforts to detect dark matter fail, alternative theories start being proposed. One such theory is Modified Newtonian Dynamics (MOND) that postulates a change in Newton’s gravitational law at certain distances. That alternative has been around for decades. A more recent alternative has been proposed by Jonathan Oppenheim, of the University College, London.
Oppenheim’s theory envisages the fabric of space-time as smooth and continuous (classical), but inherently wobbly. The rate at which time flows would randomly fluctuate, like a burbling stream, space would be haphazardly warped and time would diverge in different patches of the universe. The theory also envisions an intrinsic breakdown in predictability.
The paper, by Oppenheim and Andrea Russo, a PhD candidate at UCL, claims this take on the universe could explain landmark observations of rotating galaxies that led to the “discovery” of dark matter. Stars at the edges of galaxies, where gravity is expected to be weakest based on visible matter, ought to be rotating more slowly than stars at the centre. But in reality, the orbital motion of stars does not drop off. From this, astronomers inferred the presence of a halo of unseen (dark) matter exerting a gravitational pull.
In Oppenheim’s approach the additional energy required to keep the stars locked in orbit is provided by the random fluctuations in spacetime, which in effect add in a background hum of gravitation. This would be negligible in a high gravity interaction, such as the Earth orbiting the Sun. But in low gravity situations, such as the fringes of a galaxy, the phenomenon would dominate – and cumulatively could account for the majority of the energy in the universe.
Was there an advanced civilization on Earth before humans?
The linked article says:
Many scientists have long wondered: Is there intelligent life out in the deep reaches of space? Climate scientist Gavin Schmidt and astrophysicist Adam Frank have a different question: Was there intelligent life in the deep reaches of Earth’s history? Could we find evidence of an advanced non-human civilization that lived perhaps hundreds of millions of years ago, buried in the Earth’s crust?
This is not strictly a “solar system” mystery, but it is cosmic in scope. At the heart of it, Schmidt and Frank are asking: How likely is an intelligent life form on any planet — here or in the deepest reaches of space — to leave a mark, a sign that they existed? And for that matter: Hundreds of millions of years from now, will some alien explorers landing on Earth be able to find traces of humans if we’re long, long gone?
I posed a similar question in the opening chapter of my book, choosing dinosaurs as my starting point.
It occurred to him that dinosaurs went extinct about 65 million years ago. We think of many of the dinosaurs as impressive in their size and the way they dominated the world in their time, roaming freely over the Earth with everything as their prey and with few predators to fear. But we don’t associate them with any culture. We don’t associate them with discovering fire or building homes or creating artifacts such as pottery and tools for their use.
But my friend wondered how we know that they didn’t do any of these things. Could it be that they were actually more advanced than we give them credit for and did at least some of those things but that all the evidence has disappeared over the long time since they were wiped out? It is true that we have not discovered any artifacts dating back to the same period as the dinosaurs that show signs of conscious design. But once all the dinosaurs went extinct, anything they created would start to decompose, with most returning at various times to their elemental forms. Is there anything at all that could and perhaps should have survived until the present day that would suggest that dinosaurs had some sort of culture? We think they didn’t because we have not found anything other than their fossils. But can we be certain about this? The process of fossilization occurs when, under suitable conditions, water infiltrates the pores and cavities in bone, wood, and shell, and minerals in the water replace the organic matter and become hardened. These stony fossils are the things that last almost indefinitely, but dinosaur artifacts may not have been amenable to that process.
Let’s pose the question in another way. Human beings have created a vast number of artifacts that cover the surface of the globe. If all of us, like the dinosaurs, were to some day disappear, relatively suddenly due to some catastrophe or slowly because we failed to properly protect our environment, would at least some traces of our civilization last forever or would there come a time when there would be no sign that we lived lives that went beyond mere existence? If extraterrestrials were to arrive on Earth hundreds of millions or even billions of years after our disappearance, would they find only human fossils like we now find with dinosaurs or would they also uncover evidence that a sophisticated civilization once existed?
It seems hard to imagine that there would be no traces at all of our civilization, given the extent of the things that we have created. But it may well be the case, since there does not seem to be anything that lasts for more than a few million years or so before decomposing into elemental forms or becoming buried deep underground due to plate tectonics. If so, then why could it not be the case for dinosaur artifacts too? After all, humans have been around for a mere two million years (and modern humans only for 200,000 years) and thus produced all these things in a much shorter period than the dinosaurs who roamed the Earth for around 150 million years. Why do we believe that dinosaurs did not do anything at all during that time other than eat, sleep, and reproduce? Why could it not be that they too developed some kind of society, however rudimentary, whose traces have disappeared in the 65 million years that have elapsed since they went extinct? We can immediately think of some obvious hindrances to such advancements, such as their lack of opposable thumbs, but can we be sure that such deficiencies completely rule out any kind of culture?
My book sought to explain how the scientific community arrives at firm conclusions about which theories are worth retaining and which should be discarded. It is not a simple matter of proving some right and falsifying others. It is a much more subtle process.
A quote within the OP included,
Forever? No. But the 200 tons of material we’ve left on the moon (so far) will probably last far longer than anything on Earth. 65 million years will probably not be enough time to wipe out the traces we’ve left on the moon.
But that leads to the question: have we looked for traces of dinosaurs on the moon? 😉
I dunno nothin’ ’bout no cosmology, but I did see this a couple of days ago:
-- which, to my limited understanding, may explain the anomalous “early galaxies” recently detected but say nothing about the fast-rotating galaxies and related phenomena which gave rise to the dark matter idea in the first place.
As for the “ancient civilization” hypothesis, I see a big problem not in the absence of artifacts per se, but in the absence of evidence of extraction. The ores our ancestors found, and those modern geologists uncover, apparently occur in veins and pockets matching the patterns of rock formation, not in the lumps and clumps we’d expect from cities and dumps and tailings piles. If the dinosaurs and gorgonopsia had “civilizations”, they must have been more on the neolithic style of western hemisphere “nations”, with sophisticated biological manipulations but little-to-no metal technology.
flex @ # 1: … have we looked for traces of dinosaurs on the moon?
Don’t bother -- the Nazis hid all that by 1946!
I was surprised that the list did not include the question of what is consciousness, how does it ‘work’ and how did it evolve.
Pierce @2: Gupta’s talking about dark energy, not dark matter. Two (apparently) completely different things.
I should read articles before commenting on them 😉
Gupta was talking about both dark energy and dark matter.
I find it hard to believe that fossilized dinosaur bones could have lasted long enough for us to find them, but durable goods made in the same period could not. And I’m pretty sure our bones won’t outlast our manufactured goods either.
Raging Bee,
Aluminum cans would take about 200 years to decompose to their basic elements, plastic bottles would take about 500 years, and glass bottles would take the longest, about a million years.
While those things do take a long time to decompose compared to human timescales they are short by geological time scales.
The reason fossils last so long is that they have become mineralized, i.e. rock-like
So why couldn’t anything similar happen to any of the durable goods a civilization would produce? I’m not saying durable goods would last ~100M years in immediately-recognizable form; I’m saying that, like bones, they would become something that would still be recognizable as having once been artificial things, as fossils are recognized as having once been animal bones.
Raging Bee,
The process of fossilization involves, as the OP states, water infiltrating the pores and cavities in bone, wood, and shell, and minerals in the water replacing the organic matter and becoming hardened. So the shape of bones is retained while the material making it up has changed to minerals.
But plastics do not have the same kind of pores and cavities.
Garbage dumps. That assumes they were no better cleaning after themselves than we are.
We know how to use geology to find appropriate and useful ores. We know the geological processes that put most of them where they are. For instance, we know about kimberlite pipes We know about and how they produce diamonds. We’ll be leaving a large number of them concentrated in cemeteries, in areas surrounded by similar geology with none. Just those random patches for no good reason.
Apply the same idea to all sorts of similar minerals and ores. I suspect that our legacy of such unexplainable concentrations would be the clue to our long-vanished civilization. And we’re not seeing that from the past.
I’m sure all the concrete in our cities will leave evidence of humans that will be detected by archeologists from 100 million years in the future, not to mention the waste from nuclear power generation,
The limestones that are forming now at the bottom of the oceans will carry isotope evidence of our nuclear capabilities and the Industrial Revolution that is currently going to kill the planet.
There is some evidence of dinosaur behaviors found in the fossil record. Nests of eggs show parental care similar to birds, and some fossil sites provide evidence of Dino’s being part of large herds like cattle.
A civilization like ours would leave traces, as ahcuah notes; but a civilization at the level of the bronze age collapse for example would not be likely to leave any traces at all after 65 million years.
If there were an intelligent species that existed in a simple subsistence lifestyle/culture, with tool use/creation and language, and even written language, we might not be able to tell. But if there were an intelligent species that formed a highly technological, globe-spanning society, we would find traces of it.
Species migration/extinction would be one major clue. Disturbed sedimentary layers from excavations/buildings would be another clue. Metal objects/tools may not last long on a geologic time scale, but I would imagine some ceramic items would survive, as well as items made from surface temp/pressure stable rocks/minerals. A primitive knife knapped out of 100 million year old agate isn’t going to suddenly decay because it was modified by an intelligent tool-making species.
Large monuments/art made out of granite and such could potentially last for millions of years (like Mount Rushmore, as problematic as it is.
Also, there there is the whole bit with the intelligence of current species being reflected by the volume of the brain compared to the overall size of the animal. Human skulls look downright weird compared to most animal skulls. I can’t say for certain there was never an intelligent, tool-using species with a globe-spanning society, but I think it would be very unlikely for them to avoid leaving any traces, even hundreds of millions of years later…
@ 14 lochaber
https://www.livescience.com/largest-brain-body-size
https://byjusexamprep.com/upsc-exam/which-animal-has-the-largest-brain-in-proportion-to-its-body-size
(Humans brain to body mass ratio is around 2%.)
Always be aware when posting on this blog you are in the realm of science nerds and fact-checkers. X-D.
I’m not an expert in this field, so I’m talking through my hat, but I think it’s not brain to size ration that makes humans remarkable, but caloric expenditure. Most of our energy goes towards digesting food -- getting that energy in the first place -- but humans devote a huge amount to powering the brain compared to other species.
I suppose there’s probably no way to tell this from fossils.
good thing no one has ever commented on the intelligence of dolphins or octopuses, all that brain matter must just be functioning as bouyancy
No.
We’ve found bones, soft tissues, footprints in sand, worm burrow casts, scraps of skin, stomach contents, and even proteins and DNA from hundreds of millions of years ago. We’ve even found stromatolites -- bacterial accretions -- from over three thousand million years ago. The idea that there may be ruins and tools that have vanished without a trace, or are still lurking out there somewhere under, is so improbable it is not worth serious consideration.
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#15 Sbob
Mate, have you ever bothered to read a source before linking to it? That second link of yours appears to have been written by AI. “[E]lectrogenic elephant” ffs!
“How did life start” is tightly connected to the Fermi paradox and the various ‘great filters’, but the article is skipping that issue.
The romantic relationship issue does not really fit in. All people are unique, there is probably no ‘one size fits all’ solution.
Holms @ 18
…And a civilisation just passing through on the way to somewhere else and stopping by like in Strugatsky’s Wayside Picnic (inspiration for the film Stalker) would leave traces, not on the geologically active Earth but probably on the moon.
So is there any evidence that any ancient species did the Electrogenic Elephant Boogaloo?
😂 😂 😂
⚡️ 🐘
https://en.wikipedia.org/wiki/Mormyridae
According to Alan Weisman’s The World Without Us (2007), anything made of bronze could last until the sun cooks the earth.