a bonobo humanity?

‘Rise above yourself and grasp the world’ Archimedes – attribution

Posts Tagged ‘universe

how did the universe begin – or did it? And when will another one come along? And other conundrums

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hypothetical stuff

I thought I’d relax and tackle some pretty basic stuff for a change.

Years ago, when I was foster caring, I had a particularly smart kid under my care. One day he asked me, ‘so if the world, or the universe, started with this big bang, what caused it? Something must have. So something must’ve existed before it.’ I just said something like, ‘Well that’s when time began, along with space, because space and time are intimately connected, according to Einstein…’ He wasn’t particularly satisfied, and neither was I, though I hid it better.

So what I learned, or heard, decades ago, was that there was a big bang theory and a steady state theory, and the big bang theory won, for some reason. I also recall reading, presumably in a science magazine, that the big bang was maybe the result of a collision between two entities called branes, I think. So I’ve just looked up branes and found that they’re ‘fundamental objects in string theory’. All I know about string theory is that it seems to be going out of fashion due to lack of progress in recent years, but I could be wrong. In any case, the idea of a universe created out of nothing seems a bit puzzling to me, and the brane thing may be neither here nor there. 

Of course the big bang, or the big start-up, whatever, is an obvious corollary to an expanding universe – if we take it backwards, it contracts, presumably to nothing, or a supermassively massive and energetic dimensionless point…. A universe from nothing – I’ve heard that phrase before. Easy to say, impossible to comprehend. One vlogger or whoever speaks of ‘a tiny, infinitely dense, ball of matter’. It doesn’t take genius to recognise that this description makes absolutely no sense. ‘Immeasurably dense’, maybe, but not infinitely. 

So there was nothing, then there was cosmological inflation, presumably of that same nothing. This just can’t be right. And I believe some cosmologists agree with me on this. Not surprisingly there are lots of speculations which will remain speculation – e.g. that this cosmic inflation somehow arose from, was ‘sparked’ from, a cold dark, very ancient universe, and that our universe will head in that cold dark direction until another big bang occurs – or am I just making this up? 

So I’m sure there are people working frenetically, mathematically, on this, as well as others who just don’t care, and others who find it too mind-blowingly awesome to think too hard about, and then there are all the others. And even if you switch back to some version of the steady state model, or imagine a piano-accordion style expanding and contracting model (just because the current evidence is that the universe’s expansion is accelerating – if that’s what the current evidence is –  doesn’t mean it won’t start decelerating and eventually going backwards and contracting, I presume), you can’t necessarily be sure that its future will be anything like what you think you have worked out about its past. 

And then there’s the multiverse, which seems to be an imagined, or should I say theorised, consequence of quantum indeterminacy, perhaps among other things. Max Tegmark introduced me to this idea in his book Our Mathematical Universe, or rather he made it sound a little more plausible, but the more that book has faded from memory, the more absurd the idea has seemed. C’est la vie même. 

Others seem to be saying that the many-worlds solution to the indeterminacy problem is just a mathematical nicety, a kind of elegant solution, the ‘real-world’ implications of which can be safely ignored, or something like that. Or that the world of sub-atomic particles, or wave-particles, or smeared-out wee thingies, just doesn’t behave like the macro-world, so it can be safely ignored by everyone except those condemned to study it. And yet…

What if we too are in super-positions, until a measurement of something like our co-ordinates? I don’t know what I’m talking about really, but I’m skeptical about any division between the macro and the apparently quantum world, of which we’re presumably made up. And I know that there are much more sophisticated and/or knowledgeable people than me, mathematically speaking, who are also dissatisfied with this situation. And then there are people, I mean physicists – the only people who matter when it comes to matter – who believe it really doesn’t matter, just shut up and calculate. 

And speaking of matter, a large part of the universe’s share of the stuff is apparently dark, that’s to say not visible or even detectable to us but rather inferred, due I believe to the behaviour of stars swirling around far from the black holes at the centre of their galaxies. These stars should be travelling more slowly than the stars closer to the black hole, as gravity would predict, but that’s not happening, so some kind of matter is supposedly affecting their movements, gravitationally, but invisibly from our perspective. It doesn’t sound too convincing to a layperson like me. And as to dark energy…

Okay I’ll try coming to grips with dark energy in my small way. It has apparently to do with the acceleration of the universe’s current expansion. That’s to say, it is supposed to drive it, being energetic. This is all wrapped up in  the lambda-CDM cosmological model. CDM stands for cold dark matter and lambda is a cosmological constant. According to this model, dark energy constitutes 68% of universal energy, while dark matter contributes 27% and ordinary (baryonic) matter contributes 5%, with those more or less massless particles, photons and neutrinos, contributing more or less nothing. 

So how do we know that the universe is expanding, acceleratingly? By finding that distant galaxies are receding from we human observers at an increasing velocity, of course. And the fact that this verified discovery is known as the Hubble-Lemaître law suggests that it isn’t particularly new, at least from the perspective of modern post-Newtonian physics.

Apparently the standard view, pictured above, is that there was this initial period, known as ‘cosmic inflation’, which lasted for an infinitesimally tiny amount of time, the time it took, apparently, for nothing to become something, and which generated two types of wave, gravitational waves and density waves. What’s the difference between these two waves? Well, according to AI, which hasn’t quite become sophisticated enough to be completely deceptive, gravitational waves are ripples in space-time (which I believe we’ve detected with LIGO – the Laser Interferometer Gravitational-Wave Observatory), while density waves are ‘disturbances in the density of a medium’, like air or water. 

We’re talking about a very energetic super-expansion, and mass and energy are e- mc2 counterparts, so it created everything particulate, the building blocks of matter, which were super-hot with all that energy. It’s a bit hard to believe to put it mildly, which isn’t to say that it isn’t true. And of course what brought about that ‘big bang’ super-expansion is unknown, and must leave many cosmologists a bit pissed. 

So apparently – don’t trust me on this, or anything here – after or maybe during this expansion, matter formed, first as particles, let’s call them, then fusions of particles, all in less than a second, they say. But other theorists say there are/were ‘eternal inflations’, creating multiple universes, with all their different boundary conditions viv-a-vis light, gravity, mass-energy and such. Pretty easy to speculate, it seems. 

Theorists also speculate, and even submit proofs, sort of, that there was a period before the big bang when everything was intensely cold (fancy!), and empty, except for space, which was enormous and somehow highly energetic, until the big bang happened and made this energetic enormousness even more energetic and enormous (wow!), but there are alternative theories that…. well there are alternate theories that are quite different, calculating initial conditions that would give rise to a big bang that creates different spatial dimensions that numbers of universes could inhabit….

And the maths really works…!

Written by stewart henderson

August 12, 2025 at 9:05 pm

physics by a dummy – what’s this thing about dark matter?

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So why is there a dark matter problem, or is there? This putative stuff apparently doesn’t interact with light. My uneducated guess is that we’ve tried to measure the mass of the universe (if we ever have) through measuring light given off by stars/galaxies and found not enough to correlate with some sophisticated mathematical theories of universal mass/energy we’ve constructed. According to the PBS Space Time guy, who always sounds super smart about this stuff, recent findings by the Just Wonderful Space Telescope (JWST) of super-massive galaxies over 30 billion light years away (don’t ask) have raised speculation about ‘dark stars’ powered by dark matter – even though these galaxies are really shiny bright. So, shiny bright dark matter – what gives? 

Well needless to say, all this raises oodles of problems. First, to make a dark star you likely need a new type of particle, one that can’t ‘interact with itself’ [particle masturbation?], which apparently is a rule for dark matter. And the PBS guy goes on:

That means one dark matter particle can’t bounce off another without getting super close. That enables dark matter to avoid collapsing easily under its own gravity, which is needed to explain how it remains as a giant puffy cloud surrounding nearly all galaxies.

Slam on the brakes, I think I’ve learned something? Dark matter forms a giant cloudy stuff around all galaxies! Or remains there, a sort of remnant? I cling to words, as I don’t know anything else. For example, I don’t really understand matter collapsing under its own gravity…

So this is how stars form… Gravitational contraction and collapse is fundamental to ‘structure formation in the universe’. First we get accretion, where gaseous matter, presumably of a simple sort (hydrogen? or proto-hydrogen?) is pulled into an accretion disc, which after reaching some sort of gravitational tipping point collapses in on itself to create pockets of density like black holes and stars. But what is this gravitational tipping point? I know I’m moving away from dark matter here. Anyway, this collapse, contraction or compression raises the temperature to the point where thermonuclear fusion occurs. But somehow dark matter avoids all that. 

Anyway getting back to JWST, it has been given a number of missions or tasks, and the relevant one here is JADES (the JWST Advanced Deep Extragalactic Survey), which is an attempt to gain as much info as possible on the first galaxies or whatever to form in the universe. JWST apparently works – by design – particularly well in the infrared section of the electromagnetic spectrum:

It can see stars whose energetic ultraviolet and visible light has been stretched far into infrared wavelengths as it travelled to us through an expanding universe. 

So I gather from that sentence that infrared is longer wavelength light, and that the expansion of the universe actually stretches the wavelength of initial bursts of radiation over space-time…

It’s estimated that these ‘dark stars’ or the radiation from them, date to a period some 400 millions years after the birth of the universe. And their brightness suggests ‘super-galaxies’, common enough in the universe, but not from way back then, because there doesn’t seem to have been enough time for them to form. So these discoveries have sent cosmologists into a spin. Here’s another interesting quote from our very interesting PBS Space Time Guy: 

After all, these are the cosmic dark ages we’re peering into, a time when the ocean of pristine hydrogen forged in the Big Bang shrouded our vision across much of the electromagnetic spectrum. It’s a time when that same pristine hydrogen was able to form stars many thousands of times more massive than today.

So there seems a slight contradiction – not enough time for super-galaxies (or super-anything?) to form, yet ‘pristine hydrogen’ could form super-massive stars. Mais, continuons. The visual with this depicts Aldebaran (I have to notice everything), a star in the Taurus constellation and one of the biggest stars visible to we near-blind humans. It’s 44 times the diameter of our sun. 

So these JWST discoveries have spawned scientific papers, of course, with some suggestion that they’re ‘super-bright dark stars’ (it’s theoretical cosmology, get over it). The theory, I think, is that under certain circumstances dark stars may form via dark matter particle annihilation. The particles are annihilated by their anti-particles – except that it’s more weird than that, as it’s theorised, in a recently published paper, that the particles are their own anti-particles, causing a process of self-annihilation. 

Clearly we don’t know what dark matter actually is – one proposed candidate is a WIMP, a weakly interacting massive particle – but if we assume, with the PBS Space Time guy, that there’s lots of dark matter in the early universe, seasoned with a fair measure of hydrogen and helium, with uneven densities, accreting and pulling stuff in as mentioned before, creating structure, possibly at gigantic scales…. Well, here’s where I’ll quote the Space Time guy again, coz I don’t really get it: 

The seeds of the first giant stars would have been so-called mini-halos with masses of millions to hundreds of millions of times the Sun’s mass. The dark matter part would have a hard time collapsing due to being weakly interacting. However the gas in that halo would fall towards the centre, perhaps en route to building a star, depending on how large this halo was. 

So, I’m not quite sure where the halo idea came from, but mea culpa. Here’s some useful info from Phys.org:

The largest gravitationally bound objects in the universe are galaxy clusters that form at the intersection of cosmic web filaments. These entities are shaped and grow through massive collisions as material streams into their gravitational pull. Within the heart of some galaxy clusters are mysterious and little known radio mini-halos. These rare, dispersed, and steep-spectrum (brighter at low frequencies) radio sources surround a bright central radio galaxy and are highly luminous at radio wavelengths.

This, so far, isn’t taking me anywhere clear, but I’ll continue on in later posts, using Canto and Jacinta as my guide… But the next post will likely be on determinism (in human affairs).

References

https://en.wikipedia.org/wiki/Gravitational_collapse

https://phys.org/news/2017-08-brighten-perspective-mysterious-mini-halos.html#

Written by stewart henderson

January 15, 2024 at 1:18 pm