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beecee

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Everything posted by beecee

  1. As most have said, the escape velocity of the EH of any BH is "c". If any photon is emitted just at this side of the EH of any BH, it will be forced to arc back and be swallowed by the BH, unless that photon is emitted directly radially away. In that case the photon will always hover just above the EH, never quite getting away but also never being swallowed by the BH. What you may have seen is a discussion of the "criticality" of the spacetime curvature near the EH and inside a BH.. You or I could in effect cross the EH of the SMBH at the center of our galaxy without any undue immediate effects.....But approach and cross the EH of a stellar size BH and one would quickly be spaghettified and ripped asunder possibly even before crossing the EH. This is due to the tidal gravitational effect. Of course as one approached the singularity the spaghettification and being ripped apart will certainly take place in any BH no matter the size.
  2. Yes, polar jets do not come from within the EH of a BH. Our best theoretical model says they are caused by spinning/charged BH's, where twisted magnetic field lines, whip matter up and fling it up and away before it ever crosses the EH.
  3. Facts though are we, the Universe/spacetime are here....And unless some definition of nothing as detailed here...http://abyss.uoregon.edu/~js/ast123/lectures/lec17.html, has existed for an infinite amount of time, the something from nothing hypothesis[ https://www.astrosociety.org/publications/a-universe-from-nothing/ ] [ https://arxiv.org/pdf/1404.1207.pdf ] is the only scientific answer available.
  4. Putting it in layman's terms, space is what stops everything from being together, just as time is what stops everything from happening together, while spacetime is the multi-dimensional framework within which it is possible to locate events and describe the relationships between them in terms of space and time. The concept of spacetime follows from the observation that the speed of light is constant and invariant, Spacetime allows a description of reality that is common for all observers and Intervals of space and time considered separately are not the same for all observers. Space is real, time is real and spacetime is real: While spacetime is a non physical entitiy, it is just as real as any magnetic field is real.
  5. Plus of course any religious/supernatural view by definition is unscientific.
  6. To show the great man's thoughts on the title of the thread and what he may have meant.
  7. Again, one's definition of "nothing" is important here.....The cosmological Singularity from whence the universe and associated matter and energy arose from a fluctuation in the quantum foam....Is this pre BB quantum vacuum nothing? Empty space that we may chose to examine is not really empty but filled with spacetime and seething with virtual particles popping in and out of existence. The following link explains it much better then my own amateurish attempt... http://abyss.uoregon.edu/~js/ast123/lectures/lec17.html quote from the above link........ "With respect to the origin of the Universe, the quantum vacuum must have been the source of the laws of Nature and the properties that we observe today. How those laws and properties emerge is unknown at this time. Quantum Fluctuations : The fact that the Universe exists should not be a surprise in the context of what we know about quantum physics. The uncertainty and unpredictability of the quantum world is manifested in the fact that whatever can happen, doeshappen (this is often called the principle of totalitarianism, that if a quantum mechanical process is not strictly forbidden, then it must occur)".
  8. https://en.wikipedia.org/wiki/Religious_and_philosophical_views_of_Albert_Einstein
  9. You think so? What is your definition of nothing? Space and time, [spacetime] as we know them, did have a beginning and the matter that evolved via phase transitions and such, will also come to an end as far as we know. Perhaps what some define as nothing, is what has always been there.
  10. Speaking scientifically, this "something from nothing" appears to be the only answer/solution, although as yet, it is still speculative. What other scientific answer is there? An infinite universe? I see that as much harder to accept. https://www.astrosociety.org/publications/a-universe-from-nothing/
  11. A correct scientific statement. But I find the "universe from nothing" speculative scenario, not that hard to accept. https://www.astrosociety.org/publications/a-universe-from-nothing/ Another relevant point in my opinion, and as mentioned earlier, is one's definition of "nothing" http://iopscience.iop.org/article/10.1088/0143-0807/11/4/008/meta Perhaps one day the advent of an observable "Quantum Gravity Theory" may shed more light on this so far rather interesting scientific speculation.
  12. Nice answer to a "query" which reminds me of remarks we often see outside of science that tend to deride same by the tired old "Ahh, its only a theory" jibe.
  13. Your thoughts from my perspective, seem more like confusion. We see numerous Quazars [active galactic nuclei] at varying distances from us, and all when the universe was comparitively young. This supports the theory that in early times, the SMBH's at galactic cores were in a "feeding frenzy", having plenty of matter of all type to gobble up. It is also thought that at one time the Milky Way would also have been seen as a Quazar in the same sort of feeding frenzy.....That now has subsided after many billions of years of sweeping out a zone around our SMBH that is somewhat devoid of much of the matter that it once had and that obviously Quazars that we observe still do.
  14. The BB theory does include Inflation. In fact it is now sometimes called the BB/Inflationary model of the evolution of the universe. There are though a few hypothetical models of the exact nature of Inflation, including "Eternal Inflation" https://en.wikipedia.org/wiki/Eternal_inflation
  15. The Universe is not a big round body...The Universe is all of spacetime and all that spacetime contains. The planets, Moons, Stars, and Galaxies are all in motion as dictated by gravity. Over larger scales, the Universe is expanding. The BB happened everywhere at the same time, because everywhere was contained within the singularity from whence the BB arose..... no center, no edge/s From what I understand at this time, we have no way to indicate that the Universe is rotating or not, unless with reference to the CMBR.
  16. The clock rate is always 1 second per second for anyone measuring it from that same frame of reference. Time dilation, or the rate at which any clock ticks, will certainly change from the reference from someone in another frame of reference. The fixed nature of the speed of light,"c" leads us to the solution [special Relativity] that it is space and time which is of a variable nature according to ones frame of reference. The apparent clock rate of the Universe 13 billion years ago, from our perspective now, appears "slow" because of the constant finite nature of speed of light at "c".
  17. Travelling to the stars! A dream!! But while certainly a dream, given the time, and providing we are able to avoid any cosmological catastrophies and our own follies here on Earth, many things that we may now deem impossible, may be possible in the distant future, providing it does not contravene known physical laws and general relativity.
  18. I'm only a lay person as far as science/Cosmology is concerned but I see it as rather easy to understand that gravitational waves, are simply a distortion of spacetime..... A wave passing through the aLIGO , will lengthen space-time ever so slightly along one arm of the detector, and compress it along the other arm... Waves by definition have peaks and troughs and travel transversely progressively away from their source. Also of course the two detectors in operation that detected these GW's, did so at different instances of time, albeit it in milliseconds apart. Science is a discipline in eternal progress and while false positives from experiments do happen, scientists do learn from these false results...the BICEP2 experiment being a good example, where after further investigations and data from other experiments, the original results were falsified. While science discussion boards such as this are great for discussions and opinions to be sounded out, the scientists at the coal face, are doing the hard yards.
  19. Hi, I have only just registered on this form, so Hi again ) I am not an astronomer or scientist, just someone very interested in cosmology and who has read a great deal and been apart of another science forum. As such, my thoughts and knowledge are in layman's language. I prefer to say that what existed before the BB was "nothing that we can understand or that is covered by our models" Whatever existed before the BB, if anything, is just speculation....nothing wrong with that though. My favourite speculation of what was before the BB is a quantum foam, and that our Universe and the BB from whence it evolved started out as a fluctuation in this quantum foam...a bubble if you will. Other bubbles and BB's could also be speculated to have existed also. I suppose it must remain as speculative until at least we have a working observable testable quantum gravity theory. I'm from Sydney Australia by the way...
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