Maybe we’re forcing ourselves to work with the wrong paradigm.
Perhaps the single greatest mysteries in astrophysics are those of dark energy and dark matter, which (according to current estimates) comprise 68% and 27% of our universe today. Baryonic matter — which comprises all matter down to the subatomic level — accounts for only 4.9% of the universe.
Problem is, despite our best efforts, we can’t seem to definitively detect either dark energy or dark matter. Of course that doesn’t mean they aren’t there — after all, we can see their effects upon the visible universe. Perhaps the reason we can’t detect them really is that our present level of technology is still too primitive, or that we’re just not looking for the right set of subatomic particles.
Here is some of the evidence for the presence of dark matter:
The rotation of galaxies and galactic clusters. Astrophysicists are able to estimate the amount of baryonic mass in a galaxy, though different kinds of galaxies require different methods of measurement. However, almost all galaxies rotate so quickly that the observed mass is insufficient to maintain the physical structure of those galaxies. Instead, the galaxies should be ejecting stars like sparks from a pinwheel.
It is commonly accepted that the only possible solution is that those galaxies must be more massive than is visibly apparent, and that the additional mass must be “dark matter”. It has been postulated, however, that such dark matter resides in the “halo”, just beyond the outer edge of the galaxy, thus allowing the outer stars of the galaxy to orbit at the same velocity as stars closer to the galactic nucleus.
The same dynamic applies to galactic clusters:
Measurements of the motions of stars in other types of galaxies consistently found that galaxies of all types contained a substantial amount of seemingly invisible mass. Further, observations of groups of galaxies had been suggesting for several decades that the galaxies were moving so fast that they would fly apart unless they were embedded in a large cloud of undetected matter.
However, it has been shown that the effects of dark matter are not found in all galaxies. Last year an international team of researchers discovered galaxy NGC 1052-DF2, an “ultra diffuse galaxy” showing no apparent presence of dark matter at all.
The Cosmic Microwave Background (CMB). CMB is radiation still detectable from a very early stage of our universe, — it’s been called an “echo of the Big Bang”. If you ever wanted to see it, disconnect your television from cable, hook it up to an antenna, and turn it on — much of the static you see is CMB from perhaps thirteen billion years ago. Pretty cool, huh?
The image below is from a whole-sky survey of CMB:
One might think that if the Big Bang exploded the same way in all directions, that the CMB map should be more uniform. In fact, that’s precisely what the standard model of the Big Bang predicts. But it doesn’t. According to astrophysicist and author of “Starts With A Bang” Ethan Siegel, that’s further proof of dark matter:
The existence of dark matter leaves a characteristic imprint on CMB observations, as it clumps into dense regions and contributes to the gravitational collapse of matter, but is unaffected by the pressure from photons.
Large Scale Structure Formation. Again, building on the same precept that without dark matter, the universe should be much more uniform, here’s the Sloan Sky Survey:
Ethan Siegel (of whom I’m a fan) explains the image:
When telescopes like the Sloan Digital Sky Survey map the locations the galaxies in the Universe, with the biggest features being referred to as large-scale structure, it sees a set of patterns that couldn’t happen with only the gravity due to ordinary matter at work. We know that before the CMB, ordinary matter wasn’t able to efficiently clump into dense objects due to the oscillations from the competing forces of gravity and pressure from radiation. The structure we observe is much more advanced in its evolution given the amount of time available for objects to gravitationally collapse after the time of the CMB.
He goes on to explain how the presence of dark matter enabled regions of the universe to collapse into formations that enabled the formation of galaxies. Indeed, his article provides a compelling case for the presence of dark matter.
But what if there’s a different explanation? What if we’re just working with the wrong paradigm? After all, where the heck is it written that all the uncountable megaparsecs of empty space out there must have (for lack of a better descriptor) the same consistency?
Please don’t get me wrong. I am not an astrophysicist. I’m just a retired Navy pit snipe (or bilge snipe - I flat-out cheered with this description in The Avengers) used to working with steam and oil and seawater. I would not presume for a moment to know better than even those pursuing undergraduate degrees in astrophysics. But when I see those grand-scale maps of galaxy clusters, the first thing that comes to my mind is “oil and water”. It’s as if the formations of clusters are of a different consistency than the space surrounding them.
Let’s look first at the heliopause, the protective bubble of particles and magnetic fields surrounding our own solar system and is created by our sun. What lies beyond it? The “bow shock” that any career sailor would instinctively understand. That bow shock is a boundary, and it is so very slight…but it’s there. Voyager 2 is now experiencing the interstellar medium instead of the solar wind. If there’s such a boundary between our own solar system and the interstellar medium, why wouldn’t there also be a boundary between our galaxy’s environs and the intergalactic medium? Or, for that matter, between the boundary of galaxy clusters and the void beyond?
The heliopause is essentially a matter of radiation and our solar magnetic field, but what if there’s more to it than that? We already know that gravity “stretches” spacetime. Not only that, but while Voyager 2 has already passed through the heliopause, it won’t reach the Oort Cloud for another 300 years.
Aye, there’s the rub. The Oort Cloud — as far as we can tell — is the outer boundary of the effectiveness of the gravity of our sun. Once Voyager 2 leaves the gravitational influence of Sol, what then? Nobody alive today can possibly know, but we do know that Voyager 2 will have passed a boundary.
And when it comes to understanding interstellar space, seems to me it’s the boundaries that are one of the keys to understanding the whole.
Spacetime is not the same in all locations and times. The most obvious indication is with black holes, with the Lens-Thirring effect, also more popularly known as “frame-dragging”, wherein as a massive object spins, it warps and “drags” the fabric of spacetime around it, an effect that has been likened to putting a ball in honey and spinning the ball, the honey being so sticky that it tends to spin with the the ball. This has been observed even with Earth’s gravity well.
Thing is, if this effect has been observed at the planetary level, why could it affect the fabric of spacetime within the entirety of an object’s gravitational field, whether that gravitational field is generated by a planet, a star, a galaxy, or a galactic cluster? Yes, the effect would be greatly lessened, but it could still be extant. Again, the point is that we know spacetime is not equal in all locations and times.
But what of the fabric of spacetime itself? We can’t observe it. Thanks to the Casimir effect, there is a strong possibility of the existence of what’s been referred to as quantum foam, incredibly small Planck-length virtual particles that pop in and out of existence on an unimaginably short Planck time scale. But this process (if this theory holds) takes place in every cubic millimeter of every cubic megaparsec of the universe. For the purposes of this article, however, the pertinent question must be: is that eternal fizzing of virtual particles constant and equal throughout the universe?
If not, if that quantum foam does exist but is not equal throughout every cubic millimeter of the universe, then that opens up the very real possibility that the fabric of space itself is comprised of different consistencies (or frequency, intensity, or whatever — pick your descriptor) depending on whether it’s within a solar system, or within a galaxy, or within a galactic cluster, or outside any of those. If the consistencies are not equal, then different regions of the universe may well be likened to oil and water, thus leading to a geometry precisely like that described in the Sloan Digital Sky Survey above.
The supposition may also work on the galactic scale, for if that quantum foam is of a different consistency, then the region of spacetime containing that galaxy may itself be rotating with that galaxy, thus explaining the cause of the galaxy rotation problem.
Again, I’m no astrophysicist. I’m almost certainly wrong, and it would be the height of hubris to suppose that I would know better than any of them. But a guy can hope, and it bothers me no end that we seem to be on an endless quest to detect something that allegedly comprises far more of our universe than does baryonic matter. Therefore, if anyone leaves a comment telling me that I’m full of nightsoil and need to take a long walk on a short pier, I’ll probably agree with him or her.