Why are things in space the shape that they are?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, May 11, 2020.

  1. paddoboy Valued Senior Member


    You cannot fail to notice it – space is littered with spherical shapes, from our own Earth to the enormous planet Jupiter. Why is Nature obsessed with all things round?

    Gravity is the force that keeps us on our planet by drawing us so powerfully towards its centre. It has much the same effect on everything else floating in the cosmos, as long as it is big enough. All objects in the Universe are subject to their own force of gravity. It is one of the fundamental forces of our Universe. For objects larger than approximately one fifth the size of Earth, gravity (rather than electrostatic forces, for example) will be the dominant force determining their shape.

    As gravity pulls matter towards other matter, a sphere forms. Why? Only a sphere allows every point on its surface to have the same distance from the centre, so that no part of the object can further 'fall' toward its centre. Gravity just keeps on pulling. Given time, even the highest mountains on Earth will eventually be levelled under its power.

    Bending light

    Please Register or Log in to view the hidden image!

    ESA's Gaia will study huge numbers of stars
    The gravity of objects in our Universe, such as Jupiter, does not just attract matter, but also can actually bend light. ESA's Gaia mission, due for launch around 2010, will accurately determine the position of a large number of stars. While doing this, it will look at exactly how star light coming from distant stars is bent, as it approaches a giant body with a large gravitational field.

    Gravity bending is everywhere, on scales ranging from planetary bodies to clusters of galaxies. In this case, the bending is larger than you would expect from visible matter, so scientists think that large amounts of 'dark matter' are present. Dark matter is invisible to the telescopes, and you only detect its presence by the gravitational effect it has on light beams passing by.

    Smaller objects in space are spared from the overwhelming power of gravity, which is why we see asteroids that look like pieces of rubble. Why do these bodies have the shape that they have? Their shape arises from a simple electrostatic force. When you use your hands to push together millions upon millions of grains of sand to build sandcastles on the beach, it is the same force. The cohesion is strong enough until a stronger force like a big wave comes along and overcomes it.

    Every shape imaginable?

    Please Register or Log in to view the hidden image!

    NGC 6720, Ring Nebula, a very famous planetary nebula
    The Hubble Space Telescope has provided us with glorious images of a different shape in space. For example, consider the shapes of nebulae – those swirling clouds of gas and dust in which newly hatched stars begin to shine. In these cases, gravity is competing with the pressure of light. What gives these beautiful clouds their shape is the push and pull of the intense light given out by the stars in their infancy, which compete with each other to draw the gas and dust towards them.

    However, if the nebulae are dense enough (as in the disc around a forming star) and some perturbation causes these gas and dust particles to form areas with higher density, gravity starts to play a role again: in a chain effect. The areas can merge, forming larger and larger pieces that eventually grow to the size of planets. If they become large enough, their gravitational field becomes more significant, which encourages the inevitable formation of a familiar shape.

    Generally, then, the shape of things to come will therefore always be... spherical!
  2. Google AdSense Guest Advertisement

    to hide all adverts.
  3. paddoboy Valued Senior Member

    Always nice to discuss the wonders of gravity and how it shapes the universe we belong to, particularly with regards to some of the nonsense being spewed out and thrown about like confetti by the idiot/s in the alternative and free thoughts fringe sections.

    For example one day in the far, far distant future, [if humanity or it's evolutionary descendants are still around] we will not be able to see any external galaxy, and all that will be visible is our own MW galaxy and its merged counterparts in M31 and LMC, SMC and a few others....all merged under the force of gravity, while the accelerating expansion of the universe [DE] will see the distant galaxies all having disappeared beyond our observable horizon.
  4. Google AdSense Guest Advertisement

    to hide all adverts.
  5. LazarusLong Registered Member

    If it wasn’t for the alternate thinkers we would know what we currently know about gravity. Also, our current understanding is incomplete, so, maybe you shouldn’t bash the free thinkers. They are the ones that will make a leap forward.
    river likes this.
  6. Google AdSense Guest Advertisement

    to hide all adverts.
  7. Write4U Valued Senior Member

    Tegmark's hypothesis of recurring self-forming "patterns" in nature rests on the mathematical nature of universal properties and potentials. Specific geometric patterns can only yield specific subsequent patterns, by means of mathematical equations, most of which we have identified.

    While the number of values (patterns) in the universe is incalculable, according to Tegmark the mathematical functions are actually very simple. He estimates that some 32 relative values and a dozen or so equations can quantify and qualify everything in the universe. Which to me sounds just right. The basics have to be simple.
    There is no such thing as "irreducible complexity".

    Even in chaos, regular patterns form by natural affinity.
  8. paddoboy Valued Senior Member

    Nothing wrong with alternative thinkers per se...but obviously any alternative thinker must also know and understand what is in the box, and have some education within the relative discipline. Einstein was one. River is not one. In fact whether it is cruel, insulting or otherwise, river is simply psychotically challenged with regards to anything mainstream, and automatically rails against it, and just as obviously has similar phychotic delusions with regards to himself. I'm not the only one of that opinion, and it is due to the validity of what I have labelled him, as the reason he has been banned from contributing to the mainstream sciences on this forum. Other science forums, are far more stringent and the facts there are that he would be totally banned, many moons ago, due to his continued posting of nonsense and gobbledygook.
  9. paddoboy Valued Senior Member

    Here's another interestingly simply explainable article on gravity and why and how it shapes the universe we live in......
    A clown walks on stage. Maybe he pulls a cowboy pistol from a holster. Maybe he pops a balloon. Either way, the punch line is unavoidable: His pants fall down. Children roar with laughter, but this is far more than a mere vaudevillian sight gag. This is one of the four fundamental forces of nature in action.

    Yes, it's gravity -- a force so constant and ubiquitous that we rarely notice it. Yet without gravity, the universe as we know it could not exist. As such, gravity plays a starring role in the theory of the big bang, the immense expansion event from which the universe's billions of galaxies herald.

    According to Sir Isaac Newton's law of universal gravitation, gravity is an attractive force that acts on every particle of matter in the universe. The strength of the attraction depends on distance and mass however. If they're close enough, two particles of cosmic dust will gravitate toward each other. Meanwhile, the gravitational force of a planet will pull on objects much farther away.

    In the early 20th century, physicist Albert Einstein built on Newton's findings with his general theory of relativity, which, among other things, explained gravity not as a force but as a distortion in the shape of space-time. A particularly massive object like a star warps both the time and space around it. Time itself passes measurably slower in close proximity to such an object and curves the otherwise straight path of speeding light waves. Gravity dictates the structure of the universe, from the way cosmic bodies form to the way they orbit more massive planets or stars.

    Einstein also proposed that the universe began as a singularity, a point with zero volume and infinite density containing all the matter of the universe. Then the big bang occurred, rapidly expanding all that matter with enough ferocity to overpower the inward pull of gravity. Einstein also predicted that we'd be able to tell gravity was present during those early moments, thanks to gravitational waves (or changes in a gravitational field). All the resulting gas and dust eventually formed into the universe we know today due to gravity as well.

    Gravity is one of the four forces of nature, along with electromagnetism, strong force and weak force. All of these forces are tied up in the big bang theory. Furthermore, Einstein's groundbreaking theories about the nature of gravity were central to the understanding of the universe he presented with general relativity.

    So remember: Gravity isn't just the force that makes a clown's pants fall down. It's a key aspect of the universe, all the way back to the big bang.
  10. paddoboy Valued Senior Member

    There is also noises coming from the nutty section re other fringe ideas about how the universe was shaped.....
    Plasma cosmology
    Plasma cosmology is a non-standard cosmology whose central postulate is that the dynamics of ionized gases and plasmas play important, if not dominant, roles in the physics of the universe beyond the Solar System.[2][3] In contrast, the current observations and models of cosmologists and astrophysicists explain the formation, development, and evolution of astronomical bodies and large-scale structures in the universe as influenced by gravity (including its formulation in Albert Einstein's General Theory of Relativity) and baryonic physics.[4]

    Some theoretical concepts about plasma cosmology originated with Hannes Alfvén, who tentatively[5] proposed the use of plasma scaling to extrapolate the results of laboratory experiments and plasma physics observations and scale them over many orders of magnitude up to the largest observable objects in the universe (see box[1]).

    Cosmologists and astrophysicists who have evaluated plasma cosmology reject it because it does not match the observations of astrophysical phenomena as well as current cosmological theory. Very few papers supporting plasma cosmology have appeared in the literature since the mid-1990s.

    The term plasma universe is sometimes used as a synonym for plasma cosmology,[2] as an alternative description of the plasma in the universe.[3]

    In the 1960s, the theory behind plasma cosmology was introduced by Alfvén,[6] a plasma expert[7] who won the 1970 Nobel Prize in Physics for his work on magnetohydrodynamics (MHD). In 1971, Oskar Klein, a Swedish theoretical physicist, extended the earlier proposals and developed the Alfvén–Klein model of the universe,[8] or "metagalaxy", an earlier term used to refer to the empirically accessible part of the universe, rather than the entire universe including parts beyond our particle horizon.[9][7] In this Alfvén–Klein cosmology, sometimes called Klein–Alfvén cosmology, the universe is made up of equal amounts of matter and antimatter with the boundaries between the regions of matter and antimatter being delineated by cosmic electromagnetic fields formed by double layers, thin regions comprising two parallel layers with opposite electrical charge. Interaction between these boundary regions would generate radiation, and this would form the plasma. Alfvén introduced the term ambiplasma for a plasma made up of matter and antimatter and the double layers are thus formed of ambiplasma. According to Alfvén, such an ambiplasma would be relatively long-lived as the component particles and antiparticles would be too hot and too low-density to annihilate each other rapidly. The double layers will act to repel clouds of opposite type, but combine clouds of the same type, creating ever-larger regions of matter and antimatter. The idea of ambiplasma was developed further into the forms of heavy ambiplasma (protons-antiprotons) and light ambiplasma (electrons-positrons).[6]

    Alfvén–Klein cosmology was proposed in part to explain the observed baryon asymmetry in the universe, starting from an initial condition of exact symmetry between matter and antimatter. According to Alfvén and Klein, ambiplasma would naturally form pockets of matter and pockets of antimatter that would expand outwards as annihilation between matter and antimatter occurred in the double layer at the boundaries. They concluded that we must just happen to live in one of the pockets that was mostly baryons rather than antibaryons, explaining the baryon asymmetry. The pockets, or bubbles, of matter or antimatter would expand because of annihilations at the boundaries, which Alfvén considered as a possible explanation for the observed expansion of the universe, which would be merely a local phase of a much larger history. Alfvén postulated that the universe has always existed [10][11] due to causality arguments and the rejection of ex nihilo models, such as the Big Bang, as a stealth form of creationism.[12][13] The exploding double layer was also suggested by Alfvén as a possible mechanism for the generation of cosmic rays, [14] X-ray bursts and gamma-ray bursts.[15]

    In 1993, theoretical cosmologist Jim Peebles criticized Alfvén–Klein cosmology, writing that "there is no way that the results can be consistent with the isotropy of the cosmic microwave background radiation and X-ray backgrounds".[16] In his book he also showed that Alfvén's models do not predict Hubble's law, the abundance of light elements, or the existence of the cosmic microwave background. A further difficulty with the ambiplasma model is that matter–antimatter annihilation results in the production of high energy photons, which are not observed in the amounts predicted. While it is possible that the local "matter-dominated" cell is simply larger than the observable universe, this proposition does not lend itself to observational tests.
    more at link......................
  11. paddoboy Valued Senior Member

    Here's some more reputable debunking.......
    How I Know “Plasma Cosmology” Is Wrong:

    In my previous post, I showed direct statistical evidence that the Arp notion of non-cosmological redshifts for quasars is wrong. That was just the tip of the iceberg, though. Non-cosmological redshifts are a crank theory in astronomy that a scary fringe element keeps whinging on about. However, there’s this other crank theory that no actual respectable astronomer subscribes to, yet that seems to keep sucking in interested members of the public. That is so-called plasma cosmology (which also has an even more extreme (!!) version known as the “electric universe”). The non-cosmological redshifts for quasars model may have been a respectable alternate model in the first years or first decade after Maarten Schmidt’s identification of the then-amazingly high redshift of quasar 3C273 (that paper was in Nature, so you won’t actually get to see it, sigh). In contrast, the whole plasma cosmology paradigm was never reasonable, and is certainly not reasonable now.

    The basic idea of plasma cosmology is that electromagnetic forces in the bulk motions of astronomical objects are far more important than mainstream astronomy admits. Now, to be sure, mainstream astronomy places tremendous importance on electromagnetic forces. There’s all kind of crazy stuff going on on the Earth’s magnetosphere, as a result of the plasma from the Sun interacting with the magnetic fields of the Earth. Magnetic fields are responsible for initially collimating jets in active galactic nuclei that are observed shooting out over hundreds of thousands of light-years. So, the assertion you sometimes see that astronomers don’t train their grad students about electromagnetic forces and that astronomers don’t take into account those forces is an assertion that’s wildly wrong. However, plasma cosmology also asserts that electromagnetic forces between plasma flowing through the solar system and through the Universe and the magnetic fields of objects (or even the objects themselves, as they’ll often decide, for instance, that comets must have a substantial electric charge) make significant contributions to the motion of objects that mainstream astronomy is able to explain entirely through gravity.

    Unfortunately, rhetoric being what it is, it’s very easy to find sites on the web (and books) that promote the notion of plasma cosmology, and after reading them it’s easy for the interested but uninformed layman to be convinced. It helps that it feeds into the whole “few brave pioneers fighting the oppression of the mainstream dogma” story that seems to be so popular in (at least) American culture. How do you know whether to believe my assertion in the first paragraph above that plasma cosmology is all bunk, or a much more elegant assertion that people like me are just part of the entrenched mainstream refusing to listen to somebody with a new idea that challenges the underpinning of our whole careers? The problem is that when actual real astronomers such as myself are confronted with plasma cosmology, we have a hard time doing anything other than shaking our heads sadly, because it’s so amazingly wrong, so patently silly if you know anything, that it’s difficult even to know how to begin saying that it’s wrong.

    I’m going to try to take down plasma cosmology on two points. The first is a general point, the second is a specific point. As far as I can tell, plasma cosmology is motivated by people who just want to be different, or by people who have aesthetic or conceptual problems with things such as dark matter and cosmological distances. However, let’s go ahead and give it the benefit of the doubt (way too much benefit, but bear with me) of saying that it’s an idea inspired by trying to explain something that may not be satisfactorily explained by mainstream science. An example of something like this is MOND, or “MOdified Newtonian Dynamics”. Standard Newtonian gravity can’t explain the observed rotation speeds of galaxies. The right answer is that there is dark matter in those galaxies; we know this is the right answer because there is a whole lot of other evidence for dark matter. However, MOND was introduced as a way of modifying Newtonian gravity, rather than by introducing a new component to galaxies, to explain the flaw.

    Here’s the thing, though. Even if the “standard” explanation has a flaw, when you introduce an alternate explanation to address that flaw, your alternate explanation must explain everything the standard explanation already explains. (Strictly speaking, it doesn’t have to initially explain everything. For instance, Copernicus’ model of the heliocentric Solar System initially didn’t produce as accurate predictions for planet positions as the old Ptolemaic geocentric model did. However, your new model must at least get close, and there must be ways to improve your model to explain what the old model explained.) Given the wide range of observations that standard gravity-based expanding-Universe cosmology explains, there’s really no need for a gigantic rethink of all of it such as plasma cosmology offers. If we are to do that gigantic rethink, there has got to be a compelling observational reason beyond somebody’s aesthetic sensibilities. (For instance, Quantum Mechanics was a gigantic rethink of our understanding of the fundamental nature of reality. However, not only did it explain some troubling problems about the light emitted by hot objects, it went on to propose a whole bunch of other experiments that couldn’t have been explained without it. That’s how successful paradigm-changing theories work.)

    Given that we’re able to explain all the orbits in the solar system with a straightforward application of gravity, where’s the problem that plasma cosmology is supposed to solve? Likewise, with the whole Universe, we explain a wide range of observations with Big Bang cosmology. If we are to even bother spending ten minutes thinking about plasma cosmology, we must first know: does it even show promise to explain everything, and what does it offer that the Big Bang does not?

    In other words, plasma cosmology is a waste of time.

    However, let me also take down one of the specific pieces of the model that underpins plasma cosmology. That’s actually very difficult to do— not because the model is robust, but because it’s so ill-defined! If you go to plasmacosmology.net and follow the “technical” links, you get a bunch of text about various different “core concepts”. If you don’t know a lot about physics and astronomy, I can see where it looks like they’ve put together a well thought-out framework here, and that it’s criminal for mainstream astronomers not to address this. The problem is, if you’re a mainstream astronomer like me, and you try to figure out exactly what it is that their model here is doing, often you can’t. What you’ve got, really, is a lot of nice sounding technical jargon that ultimately doesn’t make clear what it is that they’re really saying. In short, where’s the math? If you’re going to make quantitative predictions about where things are going, we need to know the equations that go along with your nice words.

    Here’s one of the things they say about the Solar System that’s at odds with what mainstream science knows:

    Because the sun is seen to emit roughly equal quantities of ions and electrons, the solar wind is considered electrically neutral in mainstream circles. This is wrong. In reality it is a huge bipolar electric current, and the terms solar wind and solar radiation result from the fact that the mainstream refuses to acknowledge electricity in space.

    OK…. First of all, the mainstream does acknowledge electricity in space. But, never mind that. The term “solar radiation” results from the fact that the Sun is radiating. We see light coming off of the Sun. We also, via satellites, observe a stream of charged particles (of both signs, mixed together) coming off of the Sun. It seems exceedingly bizarre to assert that the term “solar radiation” comes out of some sort of global willful blindness, when it’s just a very straightforward identification of the fact that the Sun is not completely dark, and is thus, er, radiating.
    I do have one guess, based on something written further down:
    more at link, but I believe the job is done as it was decades ago in debunking Plasma/Electric universe hypotheticals.
  12. paddoboy Valued Senior Member


    The electric universe concept does not meet the National Academy of Sciences' definition of a "theory," which is "a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence" and "can be used to make predictions about natural events or phenomena that have not yet been observed.

    In physics, theories need math. That's how you predict, gather evidence, verify, disprove, and support. But EU theory isn't big on math. In fact, "Mathematics is not physics," Thornhill said. While that equation aversion makes the theory pretty much a nonstarter for "mainstream" astronomers, it is the exact thing that appeals to many adherents.
  13. paddoboy Valued Senior Member

    To remain open minded as much as one can without your brains falling out, I once read a book by a joker called Eric J Lerner, entitled "The Big Bang Never Happened" which essentially as another fool member here is pushing, a universe dominated by Plasma. This book was easily dismissed and debunked by a young GR expert, and an Astronomer on another forum, that is now defunct.
    Here are some of those dismissals and debunking, which interestingly enough, was done in the early nineties, and they obviously hold even more true today......
    Errors in the "The Big Bang Never Happened"
    1:Errors in Lerner's Criticism of the Big Bang
    Errors in Lerner's Alternative to the Big
    3:BangMiscellaneous Errors

    DETAILS AT LINK........................
  14. paddoboy Valued Senior Member

    The final convincing evidence [not that it was ever needed] of the shaping of the universe by gravity of course is BH's....Those astronomical beasts that turn back everything including light when any particular mass's Schwarzchild radius is breached or reached. And of course the evidence for BH's have been actual photographs of them, or there shadow, and the now more then a dozen discovered collisions of BH's creating gravitational waves.
  15. Write4U Valued Senior Member

    Last edited: May 28, 2020
    exchemist likes this.
  16. exchemist Valued Senior Member

    Commendable self-control. You can do it.

    Please Register or Log in to view the hidden image!

  17. paddoboy Valued Senior Member

    Nothing wrong with alternative thinkers per se...but obviously any alternative thinker must also know and understand what is in the box, and have some education within the relative discipline. Einstein was one. River is not one. In fact whether it is cruel, insulting or otherwise, river is simply psychotically challenged with regards to anything mainstream, and automatically rails against it, and just as obviously has similar phychotic delusions with regards to himself. I'm not the only one of that opinion, and it is due to the validity of what I have labelled him, as the reason he has been banned from contributing to the mainstream sciences on this forum. Other science forums, are far more stringent and the facts there are that he would be totally banned, many moons ago, due to his continued posting of nonsense and gobbledygook.
  18. DaveC426913 Valued Senior Member

    "Alternate thinkers" and "knowing how to science" are not mutually exclusive, as so many here seem to think.

    All the alternate thinkers we first and foremost, leaders in their fields of math and physics: Archimedes, Da Vinci, Newton, Einstein, etc.

    Name one free thinker that made a leap forward without having the science and math to back it up.
    paddoboy likes this.
  19. Xelasnave.1947 Valued Senior Member

    Not sure about that, in the sense that I am not sure as opposed to saying that is wrong...would it not be Georges Lemaître using GR?

    Again thank you for taking the time to construct this post it is wonderful to come here and find your interesting contribution.

  20. paddoboy Valued Senior Member

    Did I say that? Or was it from an article..What number post was it Alex?
    Singularities had something to do with the likes of Shapiro, Hawking from memory...and another bloke whose name escapes me at this time, who worked with Hawking.

    Of course now days, BH singularities defined by infinite density and spacetime curvature has largely been dismissed.
  21. paddoboy Valued Senior Member

  22. Xelasnave.1947 Valued Senior Member

    Your fourth post.
    Outside just now, there were four others and young ones "boxing".

    Please Register or Log in to view the hidden image!

  23. paddoboy Valued Senior Member

    Ahhh, beautiful photo Alex.

    OK, found the article, and I agree with you...wrong on that score.
    But perhaps he/she was illustrating the connections between GR and the BB...they do go together like a hand in a glove.

Share This Page