pantheory
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Posts posted by pantheory
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Iggy,
If I'm reading the chart correctly it looks like the beginning of accelerated expansion was at a redshift of about .77 according to the pointing arrow. This would have been about 7 billion years ago, which according to the present BB model age, would have been when the universe was half its present age. Is this the way you interpret the graph?
Here's a handy calculator of redshifts vs. time past (distance in light years).
http://hyperphysics....tro/hubble.html
Most dark energy articles and papers that I have read put this transition time a little sooner than that at a redshift of about .6 which accordingly would have been 6 billion years ago. Of course there is not enough clear supernova data at present to come up with an exact transition time concerning the dark energy hypothesis.
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I think we need large movable habitats in space, they could take very slow orbits from one asteroid to the next, refining the minerals on then and build copies of themselves and send refined metals or what ever the earth needed or sell and trade back and forth between colonies.
This concept would work better than sending out disposable probes and would be a stepping stone to colonies on the surface of planets. I think that once we begin the process of living in these freely orbiting colonies we will loose interest in planets...
Sounds good. Men could also be part of some bot expeditions as well as moving colonies, especially when/if someday they also have "holidecks," simulated vacation/ holiday spots like on the old Star Trek
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First step, I think, is to be able to survive for many years or decades in a spaceship with radiation shielding and artificial gravity. When that has been achieved, the next step would be a base under the surface of the Moon, Mars, or any asteroids. I believe artificial gravity could be created in sub-surface bases on the Moon, Mars, or asteroids by building living quarters that rotate, like a merry-go-round with floor sloping towards center, adjusting whatever gravity present to one G (I've never heard of this before, has anyone?).
A spaceship that can get water from asteroids should be able to produce their own air, water, and fuel.
I haven't heard it put all together before either. A large moving mining colony could attach itself to a large asteroid with high water content, shield it in the direction of the sun, mine it for water and other valuable on an ongoing basis, breaking water down to hydrogen and oxygen for fuel, air, water for drinking and minerals and water for growing food. With this fuel they could go wherever they wanted in the solar system while continuously being able to re-fuel as needed. Other mined valuables could be sold to a depot in Earth or lunar orbit, for example, and later transported to Earth or any other final-use depot for manufacturing.
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Is the universe generally accepted as having expanded at its' highest speed shortly after the moment of the Big Bang (inflation)? When inflation ended, expansion slowed down. Then gravity slowed down expansion even more? Finally, several Billion years ago the universe began to accelerate in expansion?
Yes, this is one of the more common interpretations. Most interpret that as a result of Riemann geometry of GR applied to Inflation theory closes the universe like a 4D spheroid with no center to it.
One problem with the directional motion of galaxies is that many believe Special Relativity would be violated (exceeding the speed of light), so the presently accepted model is instead that space itself is expanding. Some, or maybe most theorists presently think that accelerated expansion is related to the expansion of space itself. Presently there seems to be no accepted mainstream theoretical separation between the cause of the hypothetical expansion of space, and the cause for its accelerated expansion, other than the names given to it such as "quintessence," and lambda, for instance.
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...........................are there habitable planets and/or moons in our solar system? If so, how is that possible?
I think this question is based upon a precise definition of the word "habitable."
such definitions of "habitable" are:
Suitable to live in; able to be lived in; can be lived in without protection from the elements.
There are a great many places in the solar system that I expect we will live in. All must be terraformed for us to live there on the surface without a protective dome. Many of the rocky planets and moons we could eventually live in if we wished to go underground to build colonies, the moon is a prime example. The atmosphere would be manufactured and pressurized, not that hard to do but presently very costly. We could have floating colonies surrounding many planets and moons, again it is a function of cost. We could almost as easily build huge space colonies that could tour the solar system or slowly venture outward to adjacent stars taking many generations or suspend life for the journey as in sci-fi movies.
If we're talking about only the surface of the planet/moon as being habitable without protection, then there is only one known place in our solar system, and that's good old Earth.
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The equations could be wrong (that is always a possibility in an system) but, if I have the time line correct, it was noticed that angular velocities of galaxies and clusters did not match the amount of luminous material that we could observe, it was posited that a form of matter was around/about galaxies that was not interacting through emr but was gravitationally (and perhaps weakly).
There is another requirement that is needed to increase the galactic angular velocity of stars (their orbital momentum). The proposed dark matter orbiting the galaxy would need to have greater momentum than the stars within the galaxy with no explanation concerning how this hypothetical matter got its supposed momentum.
Subsequent to this it was realised that this matter should not only help our equations of motion work out, we should be able to detect it because of its gravitational lensing effect; this was born out in observation.If there is no dark matter and instead the orbital-mechanics equation are wrong then one might expect that the lensing equations that predict more matter than we can see could also be wrong since both are based upon GR, and/or that we also have been misinterpreting what we have been observing.
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More observations and studies leading to more doubts concerning dark matter and the standard cosmological model.
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The bible doesn't cover the moral decisions before us today. It is very exciting that we have this science, but do we have the wisdom to use it well?
Yes, I think we do. As you might agree, morals can come in many flavors. Atheistic societies taught/ teach their children morals concerning the well-being of the whole society should come ahead of the individual. I think such societies would also make the "proper moral decisions" as in this case. All that it takes, I believe, is educated decisions by those in the field and overseers like the FDA, and most of society will agree. The future always belongs to the brave, and the most timid will always finish last. In western societies an individual's rights and well-being is highly regarding and "the ends do not justify the means," but I think the decisions in this case would be the same: all speed ahead concerning research, and consider all possibilities the best that you can when it comes to application.
As the saying goes, "no risk no gain."
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This thread was started as a spin-off from a number of science news articles relating to several studies showing that dark matter does not match predictions of theory, and that it can't be found where it was thought that it should be found, in our solar system.
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juanrga,
Link removed is a link to a dark matter thread that I just opened based upon a seemingly well written article concerning the problems with dark matter and related theory today, where alternative ideas like MOND and others might be further discussed.
General Info:
The OP link is not presently working so here's another similar one.
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ukgasser,
.....To a chemist like me some of this QM wave-particle stuff sounds like magic,although maybe I simply don`t understand the maths!Some of the explanations of quantum mechanics seem counter-intuitive to most people that first study them. Most criticisms of QM do not involve the phenomena or experiment involved, or the maths/ equations being used, only the explanations being offered. Concerning quantum-entanglement explanations of QM, Einstein called this interpretation "spooky actions at a distance," where "magic" would be a similar description
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The link below, I think, is a well-written discussion of the theoretical problems in cosmology today. This topic and thread is for the discussion of these problems. Discuss known alternatives such as MOND etc., or speculate without bringing up too many details of an unknown model such as your own
or providing links to such models. For this, your own new thread would be better 
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You cannot find something that does not exist ...
We have lots of evidence that there is something or some influence there concerning the idea of dark matter. But it is only an assumption that it is matter since matter is the only thing that we know of that can increase the effects of gravity. Concerning galaxy clusters, for instance, reformulations of gravity like MOND (in its known forms) also require variable inputs that can be likened to dark matter inputs to Newtonian gravity in the standard formulations. In rare cases, nearly identical appearing galaxies seem to have different rotation curves of their stars. Why should there be different amounts of DM with possibly different DM distributions in "identical" appearing galaxies? but for the same reasoning why should there be different variables used/ inserted concerning alternative equations like MOND? These are some of the questions that are believed to have no obvious answers.
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Suppose Dark Matter actually exists, then won't there be some here on Earth?
After all, the Earth is part of the Universe. So if Dark Matter exists in the Universe, it should exist on Earth too. Then we could get at it, and examine its properties, at close quarters.
But this doesn't seem to be the case. Dark Matter apparently only exists at huge interstellar distances, thousands of light-years away from the Earth. Too far away for us to get our hands on the stuff.
This is convenient for theorists. They can say "Well, Dark Matter exists, but it's all so far away, that we can't show you any actual samples of it. But believe us, it's out there, a long way away....."A similar problem seems to exist with expanding space and the expansion of the universe. Expanding space (and therefore the expansion of the universe) is believed to be observable via redshifts of distant galaxies, but it cannot be seen in our neighborhood because it is believed that gravity compensates for it in our neighborhood and in the venue of groups and clusters. The same problem seems to exist for dark energy.
I expect these findings of my last link will not be the last word concerning similar studies/ observations concerning possible DM influences in our solar neighborhood, other than those presently being conducted concerning possible evidence here on Earth
As a result of such observations/ studies/ interpretations/ conclusions, many still consider dark matter and dark energy as "place holders" until more evidence concerning their nature, or better explanations, theory, etc., might come along.
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...Youngs Double Slit:I would be convinced if the material either side of the slits wasn`t susceptible to electromagnetic forces,wasn`t in a state of continuous motion at the atomic level,and thus didn`t have a potential to deflect electrons/photons by varying amounts(but perhaps maybe not to the extent or in the pattern we observe.)Surely atoms will defect electrons,and surely(classically at least) the positions of charges in an atom will vary over time and so the field an electron(or photon) has to pass through will also vary over time? Or has this been taken into account by the experimenters,and the effect discarded from the results?
The size of the slits are huge compared to an electron. The beam of electrons or photons passing through the slits are directed toward its center. It is thought that no atomic interference can occur. I would expect the material being used is non-magnetic and maybe nonmetallic materials involving no net charge. General Influences of the sidewalls of slits for these reasons, are thought to be non-existent or negligible.
De Broglie believed that both waves and particles have a physical reality. He explained that he saw no mystery at all in the double-slit experiment and was surprised that others considered it a mystery. When two slits are open but an electron goes through just one slit, the physical waves produced would go through both slits and interfere with each other and the particle producing the observed patterns. The same explanation would apply to photons. Most did not accept his very simple explanation since physical waves would seemingly involve an aether.
Photoelectric Effect:If light was neither a wave nor a particle but merely a signal then the intensity of light would merely represent the number of individual reactions that caused the light,each signal from each reaction would arrive almost together and with a strength proportional to the frequency of the light-the violence of the reaction.I can`t see how this signal would produce different results from photons.In today's physics there is no such thing as a signal without a wave or particle being involved. The idea of pure radiated energy involves waves. I agree that either a particle or wave, or both could seemingly cause the photo-electric effect, but in present theory photons alone can do this based upon Einstein's related equations which propose discrete light particles (photons), that accordingly predict the observed results.
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I am trying to understand the theory behind "slingshotting" around planets or suns. I can see the benefit of aiming towards Jupiter and missing it to reach Saturn. Let the gravitational pull of Jupiter add to your acceleration and detract a bit once you are past it so you wind up with a net profit in avg. velocity. Is there a circumstance where it will actually give you a net increase in end velocity.
Just aman
I have had at-length discussions on this subject with the mathematician and physicist Michael Minovich some 30 years ago or longer and more recently. He is the person who developed the original gravitational whip concept and calculations for NASA, which we have used ever since. You are correct in that by entering a gravitational field an object accelerates, and by leaving the system it loses this gained speed, with no net gain. The whip advantage instead comes from planetary momentum so a craft would enter the gravitational field in the direction of its planetary velocity around the sun and could leave the system in a hyperbolic passing with a net gain in velocity. The best planets for this procedure are Venus and our own planet because of both their mass and planetary velocity/ momentum. Mercury is distant and relatively small although its momentum is faster. Mars is both smaller and slower than Earth or Venus. And the outer planets although bigger, move much slower in their orbits providing a lesser gravitational assist than Venus or Earth could. For the larger planets the direction of their rotational velocity and the distance of approach is another consideration concerning a better whip or braking.
As far as an assist from the sun, when our spacecraft fly inward toward the sun they will accelerate. As they get a gravity assist from an inner planet they increase their speed again by this whip, but when flying away from the sun they lose this first advantage of accelerating inward. So the sun does not help or hurt. Gravity assists are also used for braking. When flying to the planet Mercury both Venus and the Earth can be used for braking when doing its flyby in the opposite direction of the planetary momentum. This braking system could have been used concerning Neptune, for a small fuel saving braking maneuver when settling into orbit around its moon Titan.
I have read some online explanations of these procedures that seem authoritative but are completely wrong concerning their explanations
http://en.wikipedia....chael_Minovitch
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From Ed Yong:
"... Pinheiro ended up with enzymes that could copy information between XNA and DNA, with an accuracy of 95 per cent or more. With more work, it should be possible to cut DNA out of the loop altogether, so that XNAs can be directly built from XNAs. If this is possible, Szostak adds, "In the longer run, it may be possible to design and build new forms of life that are based on one or more of these non-natural genetic polymers." ..."
Synthetic XNA molecules can evolve and store genetic information, just like DNA
More Info
Synthetic heredity molecules emulate DNA
Polymers perform non-DNA evolution
Synthetic Genetic Polymers Capable of Heredity and Evolution
Saw this in the online news today. Very interesting concerning all kinds of possible applications in medicine, and possible biological applications galore, besides probably in the foreseeable future, the creation of man-made life.
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Light is emitted from processes that (as far as I know) involve a rapid reorganization of charged particles and this light is emitted into an environment that is full of other charged particles that will adapt to any changes in EM fields and by adapting will also cause 2y adaptations etc etc. Taking into account the speed of light,a reaction that would`ve lasted perhaps a picosecond would take a lot longer to be registered by an observer as i/it would take time for the particles in any detector to move in response to the field ii/ it would be impossible to separate the effect of the surroundings from the localized effects from the actual reaction.As the rest of the universe is more substantial than the few participants in a reaction,wouldn`t any adaptation by the environment disguise the observed effects from the reactants?Wouldn`t the observed effects from reactants and environment appear as waves?I don`t know where the flaw is in this logic!
Do (Could?) all processes that produce light involve a reorganization of charged particles?
Would surrounding matter be affected by very rapid positional changes in charged particles?
Light is an EM field and will effect charged fundamental particles,won`t it?
Could environmental effects disguise the effects from the process itself?
Does the concept of the speed of light allow alternative interpretations for the nature of light?
Does the speed limit of c mean that any sudden process would appear as waves ,as 'seen' by groups of particles?
Can any detector (since they are all made of matter and there is a speed limit of c)react instantly to a stimulus?
Would environmental effects cause apparent wave/particle behavior? (Wouldn`t individual particles react differently depending on their positions relative to neighbors and collectively cause waves?)
Are we trying to attribute wave particle effects to a carrier when it could just as easily be attributed to the medium in which the processes occur?
If this is right(!!) why do we need photons and light waves?
In the 17th century Newton proposed light as being particles based upon his corpuscular theory and model. Huygens then followed with his wave theory of light toward the end of the century. Although Newton's model prevailed for about 100 years eventually the bulk of theorists eventually adopted Hoygen's model because the corpuscular model failed to adequately explain the diffraction, interference and polarization of light, and because of new evidence concerning the wave nature of light revealed by Tomas Young concerning his double slit experiment and other experimenters of the 18th and 19th century. It wasn't until the late 19th century and the early 20th century that the idea of light as a particle was again postulated by Max Planck which he called quanta (as in Quantum Mechanics) and Alberta Einstein who called the same proposed particles photons.
The idea was that since they could not find an aether to carry the waves of EM radiation, they proposed the idea of waves of pure energy having no medium at all. To explain the particles/ quanta/ photons they proposed particles moving through generally empty space between stars, and later between galaxies. Theory evolved that depending on the observers point of view, light could be considered a particle or a wave, but not both at the same time. This is the present view which is based upon interpretations in Quantum Mechanics with the realization that atomic and other quantum particles also have a wave nature to them as shown by De Broglie. So present theory is based upon the evolution of Quantum Mechanics of which this assertion of the duality of EM radiation is one of its foundation pillars.
Although there are many new and modern aether theories, most theorists still are not interested believing that the aether was long ago disproved. If we ever discover an aether as "the medium in which the process occurs" (in your words) then at that time we might consider that EM radiation is both a particle and a wave at the same time. Maybe ideas like the particles/ photons are produced by the waves and are surfers within them, or that light particles as they move in groups at a given frequency, push up the waves, or other such ideas. But presently such ideas are not ever considered by mainstream theorists is Quantum Mechanics since there seemingly is no present reason for such speculation.
Based upon your doubting statement, I too also think there are flaws in present logic of Quantum Mechanics concerning this and other interpretations, and so did a great many other theorists such as Einstein, De Broglie, Schrodinger, etc. The formulations were not in question by them, only the logic concerning why the formulations should be valid. Einstein believed QM was merely a predictive system of statistics and equations formulated to match observations. Heisenberg, Born, Wheeler, and others believed the system represented a fundamental character of nature at the quantum level proposing such things as probability waves concerning no actual exact physical location or momentum of particles in motion, as well as wave particle duality of EM radiation, etc.
The answer to most of your questions can be found in QM theory (whether present interpretation may or may not seem to have logic to it), and other questions you have asked have various possible QM mainstream answers or interpretations.
http://en.wikipedia....antum_mechanics
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A new look at dark matter and dark energy is uniquely presented in an interesting demo program available at link: http://dl.dropbox.com/u/26262175/SagitariusBRprogramDescription.pdf
I am interesting if anyone knows other educational programs on dark matter or dark energy which are available on the Internet
There is mounting evidence that dark matter is not conforming to any well-known dark matter theories. Although most still believe there is much evidence to support the idea that there is something there that may behave like matter there still is no evidence for its character, or even to say for sure that it is matter -- see the science news section of this forum concerning -- is dark matter really matter? Most would agree that at least it is a placeholder for something that we still don't understand.
Dark energy is also just theory. The Nobel Prize was recently granted for its discovery but it too may be only a placeholder for something still not understood concerning what it is. There are a great number of hypothesis concerning both of them but the related observations are often not confirming the related theories. Once you read the Wiki pages on both you can understand present ideas of them concerning their educational value. Beyond that ideas can be quite speculative.
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.....I've heard several times that if a person were to fall into a supermassive black hole, that they would survive quite comfortably for a while even after they've crossed the event horizon due to the lack of significant tidal forces. But there's one thing I don't understand. From what I've read about black holes, the event horizon is the absolute point of no return; it's the point at which outward movement becomes impossible....
I've read such things also. But you probably realize that ideas of what is happening near, at, or inside a black hole's event horizon is theory at best, and often just speculation. Near the event horizon where a accretion disc and torus can be observed, speeds can approach 10% the speed of light by observational calculations. It is thought by many or most theorists that at these speed within a torus that molecular and atomic ionization will first occur. Following this friction would bring about molecular disintegration. Following this the resultant atoms would probably remain ionized and the tidal forces at or inside the event horizon are thought to be able to cause spaghettification, being the linear stripping of atoms down to primarily nuclei and electrons (pasma). In active galaxy nuclei (AGN) of galactic black holes, even the atomic nuclei could be further fissioned down by the heat and compression into the lightest nuclei providing the energy for polar galactic jets in such galaxies. This is one proposed model. There are few theoretically passive models like the one you read, to my recollection, that would allow a passive transition of a spaceship, for instance, through the event horizon unscathed.
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All my pervy dreams come true.... No wait, tera hertz waves? About as much fun as looking at the Pilsbury dough boy...
Maybe with stereoscopic (or other) imaging methods and programming, such imaging translations might be better than an ultrasound image, I would hope
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A new technology: A peeping Tom and voyeur's dream come true? Superman vision from a cell-phone? Wanna see my favorite pics on my cell?
Also seemingly future medical applications along with countless other conceivable and more socially acceptable, wonderful applications? 0 -
Saw this in the science news today.
The article is entitled "Serious Blow to Dark Matter Theories?
http://www.eso.org/p...c/news/eso1217/
The purpose of the study was to find dark matter around the sun and its surrounding mass relating to gravitational influences within our solar system. According to their observations and conclusions, none was found.
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If you were given no knowledge of modern theories what would you guess black holes would be like from observations?
-They seem to emit no light.
-Massive amounts of material seem to be being shot out from areas in the vicinity of black holes- Do spiral bars come from there?
Is that all we know?If so,what would be a best guess for the nature of black holes and how much does it agree with theory?
What other observations agree with the conventional wisdom that they are singularities?
(Sorry,another speculative BH topic)
They still would appear to be very massive based upon their gravitational influences, so I would guess them to be highly condensed burned-out stars absent the BB theory and present stellar evolution theory.
Black holes as a Singularity is mathematical theory absent any possible observational confirmation at full scale, therefore conceivably just one possibility concerning black holes in general. Black hole models as a more condensed form of matter is the alternative theoretical idea.
Black holes are even more condensed than neutron stars. For example, a 1-solar-mass black hole would have a radius of about 2 mi (3 km).(quote from top link, shown below)
http://www.answers.c...tional-collapse
http://www.answers.com/topic/gravitational-collapse#ixzz1sKMjRIbh
There are black hole hypothesis proposing such ideas as quark stars, compressed fundamental particles or strings of some kind, and a number of other proposals and ideas.
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michel123456,
Of course there is a difference between Space & Time. Space is 3D and Time is 1DI think your description of the comparison of space and time is apt, but I think that dimensions are just man's mathematical description of reality. 1D space is a line with two directions. The sum of time seemingly could be characterized in 1D. But the progression of time might better be characterized as a vector which is more restrictive, which I believe may more aptly describe man's invention of the concept of the progression of time in the first place.
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Dark Matter is not matter?
in Science News
Posted · Edited by pantheory
There are a great many non-mainstream theories that propose and support a flat universe. One of the only theories that does not necessarily predict a flat universe is the BB model, concerning most of its variations. Any theory that uses GR will predict numerous possibilities other than a flat universe. Most theories that either have MOND or another gravity model without dark matter generally must predict a flat universe if space cannot curve or warp. Most, but not all of the alternative flat-universe models are infinite-universe models. Examples are steady-state models of Hoyle and many others. Plasma Cosmology is an infinite model. Some tired light models are infinite, etc. Paul Dirac's expanding matter and space model proposes a flat universe. Most diminution of matter models propose a flat universe, etc.
So the idea of a non-flat universe is unique to the BB model or other models that support GR, in my opinion. What sayeth you my friend?
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