Here. The Science Fictions series at your fingertips (cosmology).
Comments
Glad you noticed. You might google the phrase.Petrushka
February 2, 2015
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Petrushka:
Was it not an argument when the Germans bombed Pearl Harbor?
I am sure that in some universe somewhere the Germans bombed Pearl Harbor and the Japanese bombed Berlin.
What universe are you in?Mung
February 2, 2015
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Was it not an argument when the Germans bombed Pearl Harbor?Petrushka
February 2, 2015
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skram:
That’s not even an argument.
It is to me. Think about it. But if you don't get it, then I'm wasting my time, no pun intended.Mapou
February 2, 2015
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Petrushka:
Nothing wrong with Newton that can’t be fixed with a few epicycles.
Which is what GR is, a cheesy modification of Newtonian physics. Did you know that GR's equations make use of Newton's gravitational constant G?
In the end, both GR and Newtonian physics failed to explain gravity. In this regard, they are no better than Ptolemaic epicycles.Mapou
February 2, 2015
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Mapou:
Why? Simply because time is time.
That's not even an argument.skram
February 2, 2015
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Mapou:
IMO, the effect has very little to do with Mercury’s speed (it’s negligible) but the fact that Mercury is closer to the sun.
One is related to the other. The smaller the orbit, the faster the planet moves. Kepler's third law.
In this respect, the only thing that GR offers is gravitational clock slowing.
If that were the case, the orbit would be elliptical and thus closed. No precession of the perihelion. That contradicts observations.skram
February 2, 2015
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skram:
Mapou:
Spacetime is not called Einstein’s block universe for just grins and giggles. Why? Simply because time cannot change by logical definition, i.e., changing time leads to a self-reference.
You have a misconception that velocity is computed in relativity as the derivative with respect to time, (dx/dt, dy/dt, dz/dt, c dt/dt). That isn’t the case. It is computed with respect to the proper time, which is equal to the interval d? defined as follows:
c^2 d?^2 = c^2 dt^2 ? dx^2 ? dy^2 ? dz^2.
As a result, the time component of 4-velocity is not simply a fixed constant.
You are mistaken. If you think that the use of one time parameter (proper time) can show that another time reference can change, you must be prepared to show that proper time can also change. Why? Simply because time is time. What's good for the goose is good for the gander.Mapou
February 2, 2015
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skram:
That won’t be enough to explain the observed precession of Mercury’s perihelion. Once we take into account the influence of other gravitating bodies (within classical physics), there remains a discrepancy of 43 arc seconds per century. Einstein’s theory of general relativity predicts just that amount of extra precession.
The effect is small because even Mercury is moving fairly slowly on the scale of the speed of light. It is nonetheless observable and is in good agreement with general relativity.
IMO, the effect has very little to do with Mercury's speed (it's negligible) but the fact that Mercury is closer to the sun. In this respect, the only thing that GR offers is gravitational clock slowing. And you don't really need GR for this since clock slowing is a simple consequence of the light speed experiments conducted by Michelson and Morley.Mapou
February 2, 2015
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Nothing wrong with Newton that can't be fixed with a few epicycles.Petrushka
February 2, 2015
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Mapou:
Spacetime is not called Einstein’s block universe for just grins and giggles. Why? Simply because time cannot change by logical definition, i.e., changing time leads to a self-reference.
You have a misconception that velocity is computed in relativity as the derivative with respect to time, (dx/dt, dy/dt, dz/dt, c dt/dt). That isn't the case. It is computed with respect to the proper time, which is equal to the interval dτ defined as follows:
c^2 dτ^2 = c^2 dt^2 − dx^2 − dy^2 − dz^2.
As a result, the time component of 4-velocity is not simply a fixed constant.skram
February 2, 2015
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Mapou:
The truth is that Newtonian physics is so accurate, it is the physics used by NASA during the Apollo missions and to land probes on Mars. Take Newtonian physics, add to it the speed of light limit and gravitational clock slowing and you have an approximation that’s just as good as any, if not better.
That won't be enough to explain the observed precession of Mercury's perihelion. Once we take into account the influence of other gravitating bodies (within classical physics), there remains a discrepancy of 43 arc seconds per century. Einstein's theory of general relativity predicts just that amount of extra precession.
The effect is small because even Mercury is moving fairly slowly on the scale of the speed of light. It is nonetheless observable and is in good agreement with general relativity.skram
February 2, 2015
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Piotr:
You claimed relativity was falsified by the stability of planetary orbits, apparently poninting to the instantaneity of gravitational interactions.
I did not say that this is what falsifies GR. Relativists can always claim that not all the data is in and that future experiments will detect gravitational waves. What falsifies GR is the fact (deny at your own detriment) that nothing can move in Einstein's spacetime. Zilch. Spacetime is not called Einstein's block universe for just grins and giggles. Why? Simply because time cannot change by logical definition, i.e., changing time leads to a self-reference. The movement of a clock is not evidence for time changing. Time dilation is a misnomer.
Well, you was wrong about it, because Einstein’s equations do not lead to the kind of instability you suggested. Relativity is not just Newtonian physics plus a speed limit.
The truth is that Newtonian physics is so accurate, it is the physics used by NASA during the Apollo missions and to land probes on Mars. Take Newtonian physics, add to it the speed of light limit and gravitational clock slowing and you have an approximation that's just as good as any, if not better.
Einstein had to artificially introduce all sorts of contortions and other just-so explanations to make GR work. It's ugly compared to Newton's simple little equation.Mapou
February 2, 2015
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We see it in physics, biology, astrology, archaeology, etc.
Yeah, especially in astrology.
You claimed relativity was falsified by the stability of planetary orbits, apparently poninting to the instantaneity of gravitational interactions. Well, you was wrong about it, because Einstein's equations do not lead to the kind of instability you suggested. Relativity is not just Newtonian physics plus a speed limit.Piotr
February 2, 2015
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Piotr:
Mapou,
All the planets and moons move in their orbit as if gravity were instantaneous, just as predicted by Newton. Otherwise, the solar system would be unstable and would have fallen apart a long time ago.
Einstein’s field equations also make the gravitational field of a moving body (to be more precise, a body in free fall along a geodesic) act as though gravity were instantaneous (it isn’t, really: perturbations of the field, i.e. gravitational waves, propagate at c). The difference becomes non-negligible in some extreme circumstances, like a system of two very massive, very closely orbiting objects (whose orbital decay is measurable and consistent with Einstein’s predictions).
Believe me. I have heard all this before. Scientists have a bad habit of forcing nature to conform to their theories instead of the other way around. We see it in physics, biology, astrology, archaeology, etc. The use of Einstein's field equations to explain the observed instantaneous nature of gravity (other than the fact that equations do not explain anything) is an especially egregious violation of Occam's principle. The reason that gravity is not considered instantaneous (nonlocal), as Newton correctly assumed, is historical and rather embarrassing. Einstein insisted that nothing can move faster than light and, as a result, came out against what he called "spooky action at a distance". Einstein was right that nothing can move faster than light but he was wrong about nonlocality which does not involve motion. Gravity is obviously an energy conservation phenomenon. All conservation laws are non-local by definition.Mapou
February 2, 2015
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Yes methink, the dust disappointed the string guys just as much as the multiverse guys.ppolish
February 2, 2015
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Materialism cannot explain gravity...Joe
February 2, 2015
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14 #Skram
Isn't it a slightly different relativistic effect, occurring when the masses are very unequal? The lighter body follows a geodesic which is not the same as a Newtonian orbit, but that doesn't lead to any appreciable orbital decay. When both bodies are comparably massive (that is, their contribution to the gravitational field is similar) and close together, the emission of gravitational waves is strong enough to carry the system's energy and angular momentum away, making the orbits unstable.Piotr
February 2, 2015
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Me-Think, I’m certainly not qualified to know which inflation models were supported and which models were weakened, but what I do know for certain is that a purely unguided (atheistic/materialistic) inflationary model would, (much like Plantinga's evolutionary argument against naturalism), lead to the epistemological failure of science itself. One of the chief proponents of various multiverse models himself admits this:
WHAT SCIENTIFIC IDEA IS READY FOR RETIREMENT? Infinity - Max Tegmark - January 2014
Excerpt: Physics is all about predicting the future from the past, but inflation seems to sabotage this: when we try to predict the probability that something particular will happen, inflation always gives the same useless answer: infinity divided by infinity. The problem is that whatever experiment you make, inflation predicts that there will be infinitely many copies of you far away in our infinite space, obtaining each physically possible outcome, and despite years of tooth-grinding in the cosmology community, no consensus has emerged on how to extract sensible answers from these infinities. So strictly speaking, we physicists are no longer able to predict anything at all!
This means that today’s best theories similarly need a major shakeup, by retiring an incorrect assumption. Which one?
Here’s my prime suspect: infinity.
(actually the ‘theory’ that needs to be retired is the philosophy of materialism in general)
MAX TEGMARK – Physicist
http://www.theguardian.com/science/2014/jan/12/what-scientific-idea-is-ready-for-retirement-edge-org
Why I Still Doubt Inflation, in Spite of Gravitational Wave Findings By John Horgan - March 17, 2014
Excerpt: Indeed, inflation, like string theory, has always suffered from what is sometimes called the “Alice’s Restaurant Problem.” Like the diner eulogized in the iconic Arlo Guthrie song, inflation comes in so many different versions that it can give you “anything you want.” In other words, it cannot be falsified, and so–like psychoanalysis, Marxism and other overly flexible hypotheses (mmm Darwinism?)–it is not really a scientific theory.
http://blogs.scientificamerican.com/cross-check/2014/03/17/why-i-still-doubt-inflation-in-spite-of-gravity-wave-findings/
i.e. If it is not falsifiable then it is not science!
Steinhardt, one of inflation theory’s creators, commented in 2013 on the trend in evidence:
Inflationary paradigm in trouble after Planck2013
Anna Ijjas, Paul J. Steinhardt, Abraham Loeb
Excerpt of abstract: More important, though, is that all the simplest inflaton models are disfavored statistically relative to those with plateau-like potentials. We discuss how a restriction to plateau-like models has three independent serious drawbacks: it exacerbates both the initial conditions problem and the multiverse-unpredictability problem and it creates a new difficulty that we call the inflationary “unlikeliness problem.”,,
http://arxiv.org/pdf/1304.2785v2.pdf
Uncommon Descent's own Robert Sheldon, one of the earliest and most vocal critics of the gravitational wave finding last year, (and who suffered a fair amount of 'you don't have a clue' ad hominem from Dr. Luke A. Barnes for doing so), had this to say about inflation (and string theory),,,
Sean Carroll channels Giordano Bruno - Robert Sheldon - November 2011
Excerpt: 'In fact, on Lakatos' analysis, both String Theory and Inflation are clearly "degenerate science programs".',,,
http://rbsp.info/PROCRUSTES/sean-carroll-channels-giordano-bruno/
Of related note, here is a early criticism on the fine-tuning problem for inflation by Roger Penrose which still is as valid now as the criticism was when he first made it:
Inflation
Excerpt: In order to work, and as pointed out by Roger Penrose from 1986 on, inflation requires extremely specific initial conditions of its own, so that the problem of initial conditions is not solved: “There is something fundamentally misconceived about trying to explain the uniformity of the early universe as resulting from a thermalization process. […] For, if the thermalization is actually doing anything […] then it represents a definite increasing of the entropy. Thus, the universe would have been even more special before the thermalization than after.”[104]
Penrose, Roger (1989). “Difficulties with Inflationary Cosmology”. Annals of the New York Academy of Sciences 271: 249–264.
http://en.wikipedia.org/wiki/Inflation_%28cosmology%29#Criticisms
i.e. in inflation's attempt to 'explain away' the fine-tuning of the flatness and 'roundness' (i.e. homogeneity) of the universe, inflation requires even more fine-tuning at its initial point. i.e. Inflation, by pushing the fine-tuning problem back a notch, actually exasperates the problem of fine-tuning for atheists/materialists rather than solves it.
While that is certainly an insurmountable problem for the atheist, (who, by faith and not evidence, believes that the extreme order of the universe can 'randomly emerge' from complete chaos), none of this should be surprising for the Theist who holds God created and sustains this universe:
Around the 13:20 minute mark of the following video Pastor Joe Boot comments on the self-defeating nature of the 'bottom up' atheistic worldview in regards to trying to explain why the universe, or anything in it, takes the ordered structure that it does:
Defending the Christian Faith – Pastor Joe Boot – video
http://www.youtube.com/watch?v=wqE5_ZOAnKo
"If you have no God, then you have no design plan for the universe. You have no prexisting structure to the universe.,, As the ancient Greeks held, like Democritus and others, the universe is flux. It's just matter in motion. Now on that basis all you are confronted with is innumerable brute facts that are unrelated pieces of data. They have no meaningful connection to each other because there is no overall structure. There's no design plan. It's like my kids do 'join the dots' puzzles. It's just dots, but when you join the dots there is a structure, and a picture emerges. Well, the atheists is without that (final picture). There is no preestablished pattern (to connect the facts given atheism)."
Pastor Joe Boot
bornagain77
February 2, 2015
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Piotr,
Mercury is a great example. It moves almost as if gravity acted instantaneously. But then there is some slow precession of the planet's perihelion that is precisely due to relativistic effects. Beyond Newtonian gravity.skram
February 2, 2015
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Mapou,
All the planets and moons move in their orbit as if gravity were instantaneous, just as predicted by Newton. Otherwise, the solar system would be unstable and would have fallen apart a long time ago.
Einstein's field equations also make the gravitational field of a moving body (to be more precise, a body in free fall along a geodesic) act as though gravity were instantaneous (it isn't, really: perturbations of the field, i.e. gravitational waves, propagate at c). The difference becomes non-negligible in some extreme circumstances, like a system of two very massive, very closely orbiting objects (whose orbital decay is measurable and consistent with Einstein's predictions).Piotr
February 2, 2015
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Me_Think,
Oh, you mean colliding branes, right? What you wrote at #10 gave me a surreal vision of two barns moving across a farmyard and crashing into each other.Piotr
February 2, 2015
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Mapou:
I don’t really know (I suspect it might be caused by tidal forces) but neither do you.
Perhaps you should speak for yourself, Mapou. General relativity makes quite specific predictions for the power of gravitational waves produced by a rotating mass. These emitted waves carry away energy from the binary pulsar system and cause a slowdown in the rotation rate. The computed slowdown matches quite well the observed one.skram
February 2, 2015
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bornagain77 @ 12,
One of cosmic inflation theory’s creators (Steinhardt) now questions own theory – April 2011
Exactly. He abandoned one of the inflationary model - that is what I meant by this @ 10 :
...you would rather go with authors who want to promote their own barns colliding model.
he is promoting his colliding barns model of universe's evolution now. Even Stephen Hawking who predicted Black holes, now says there are no black holes - that doesn't stop NASA from discovering black holes !Me_Think
February 2, 2015
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One of cosmic inflation theory’s creators (Steinhardt) now questions own theory - April 2011
Excerpt: Cosmic inflation is so widely accepted that it is often taken as established fact. The idea is that the geometry and uniformity of the cosmos were established during an intense early growth spurt.
But some of the theory’s creators, including the author, are having second thoughts. As the original theory has developed, cracks have appeared in its logical foundations.
Highly improbable conditions are required to start inflation. Worse, inflation goes on eternally, producing infinitely many outcomes, so the theory makes no firm observational predictions.
Scientists debate among (and within) themselves whether these troubles are teething pains or signs of a deeper rot. Various proposals are circulating for ways to fix inflation or replace it.
- Scientific American (April 2011),
Paul J. Steinhardt,,,
Inflation adds a whole bunch of really unlikely metaphysical assumptions — a new force field that has a never-before-observed particle called the “inflaton”, an expansion faster than the speed of light, an interaction with gravity waves which are themselves only inferred– just so that it can explain the unlikely contingency of a finely-tuned big bang.
But instead of these extra assumptions becoming more-and-more supported, the trend went the opposite direction, with more-and-more fine-tuning of the inflation assumptions until they look as fine-tuned as Big Bang theories. At some point, we have “begged the question”. Frankly, the moment we add an additional free variable, I think we have already begged the question. In a Bayesean comparison of theories, extra variables reduce the information content of the theory, (by the so-called Ockham factor), so these inflation theories are less, not more, explanatory than the theory they are supposed to replace.,,, after 20 years of work, if we haven’t made progress, but have instead retreated, it is time to cut bait.
https://uncommondescent.com/cosmology/cosmology-one-of-cosmic-inflation-theory%E2%80%99s-creators-now-questions-own-theory/
"In so far as a scientific statement speaks about reality, it must be falsifiable; and in so far as it is not falsifiable, it does not speak about reality."
Karl Popper - The Two Fundamental Problems of the Theory of Knowledge (2014 edition), Routledge
http://izquotes.com/quote/147518
Infinity and Beyond: The Ultimate Test - Nov. 2014
Excerpt: If modern physics is to be believed, we shouldn’t be here. The meager dose of energy infusing empty space, which at higher levels would rip the cosmos apart, is a trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion times tinier than theory predicts. And the minuscule mass of the Higgs boson, whose relative smallness allows big structures such as galaxies and humans to form, falls roughly 100 quadrillion times short of expectations. Dialing up either of these constants even a little would render the universe unlivable.,,,
“The multiverse idea is baroque, unnatural, untestable and, in the end, dangerous to science and society.”
Paul Steinhardt - originally worked on eternal inflation theory, but has now repudiated it as 'unscientific'
http://www.quantamagazine.org/20141103-in-a-multiverse-what-are-the-odds/bornagain77
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humbled @ 9
Binary pulsars losing orbital energy by giving out gravitational waves and spiraling into the orbit at 7mm per day was predicted by Einstein in 1915! It is a marvel that the observations by Parkes, Jordell Bank and Green Bank telescopes match what was calculated in 1915.Me_Think
February 2, 2015
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ppolish @ 6, bornagain77 @ 7
Every one who has ever read any theory of inflation should know that r, the ratio of tensor (gravitational wave perturbation) to scalar (density perturbation), has to be low. If r =0.2, as BICEP2 showed, then the amount of inflation field rolling would be Sqrt[0.2]*10 = 4.47 , which is far far higher than Planck scale ! How the heck will anyone reconcile that figure with slow rolling inflation field? That's the reason sensible inflation theories predict r to be less than 0.01. In fact, the earlier Planck data has an upper limit of r as 0.1 !
It is not surprising that right from the day of BICEP2 preprint, every sensible physicist pointed out dust could be the reason for the B mode, so unless you find that r is less than 0.01, and prove that it is due to dust or lensed B mode, you can't rule out primordial gravitational wave.
If you want to go from inflation to multiverse, the only way is to link some string theory model to inflation, which means you believe in compactified dimensions and greater than 10^500 universes, or you hate inflation so much that you would rather go with authors who want to promote their own barns colliding model.Me_Think
February 2, 2015
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Mapou, i agree with what you said. I've come to the conclusion that there is little difference between a scientist and a politician these days and as such I take everything they say with a pinch of salt.humbled
February 2, 2015
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skram:
Mapou,
If there are no gravitational waves, how do you explain the slowing down of the binary pulsar PSR 1913+16?
I don't really know (I suspect it might be caused by tidal forces) but neither do you. I do know this: Physicists are totally clueless as to what causes gravity. Heck they don't even know what causes inertial motion. So any pronouncement from the physics community concerning gravity waves or the like should be taken with a large grain of salt.Mapou
February 1, 2015
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as to:
"BICEP2 result which was withdrawn is about gravitational waves, not multiverse."
Gravitational waves were held to be evidence for inflation. Yet, inflation results in what can be termed a 'unconstrained' multiverse in which every possibility is explored (which led of of the founders of inflation theory to reject inflation since inflation predicts everything and can be falsified by nothing).
Thus gravitational waves were held to be evidence for a multiverse. Thus, with the retraction, the supposed evidence for the 'unconstrained' multiverse of inflation is gone.
Moreover, the evidence for inflation is gone as well. And since inflation was originally postulated to 'explain away' why the universe is as homogenous and flat as it is, then that means the atheists/materialists are left without a clue as to how to give a coherent explanation for the finely tuned flatness and homogeneity of the universe. Yet the Theist is doing quite well in both regards:
Wilkinson Microwave Anisotropy Probe - Main result
Excerpt: The microwave background is very homogeneous in temperature (the relative variations from the mean, which presently is still 2.7 kelvins, are only of the order of 5x10?5.)
http://en.wikipedia.org/wiki/Wilkinson_Microwave_Anisotropy_Probe#Main_result
Planck satellite unveils the Universe -- now and then (w/ Video showing the mapping of the 'sphere' of the Cosmic Microwave Background Radiation with the satellite) - 2010
http://phys.org/news197534140.html#nRlv
Proverbs 8:26-27
While as yet He had not made the earth or the fields, or the primeval dust of the world. When He prepared the heavens, I was there, when He drew a circle on the face of the deep,
Job 26:10
He has inscribed a circle on the face of the waters at the boundary between light and darkness.
"The Universe today is actually very close to the most unlikely state of all, absolute flatness. And that means it must have been born in an even flatter state, as Dicke and Peebles, two of the Princeton astronomers involved in the discovery of the 3 K background radiation, pointed out in 1979. Finding the Universe in a state of even approximate flatness today is even less likely than finding a perfectly sharpened pencil balancing on its point for millions of years, for, as Dicke and Peebles pointed out, any deviation of the Universe from flatness in the Big Bang would have grown, and grown markedly, as the Universe expanded and aged. Like the pencil balanced on its point and given the tiniest nudges, the Universe soon shifts away from perfect flatness."
~ John Gribbin, In Search of the Big Bang
Job 38:4-5
“Where were you when I laid the earth’s foundation?
Tell me, if you understand.
Who marked off its dimensions? Surely you know!
Who stretched a measuring line across it?