Owner: future of physics URL:http://softcracked.googleapges.com/pb.html Join Date: Thu, 11 Oct 2007 04:25:46 -0500 Rating:0 Site Description: Discipline of Science dealing with the properties of matter and energy. !!!---This blog is particualy for question that will be asked and their answers!!! It is not for journal and research work or an article. Site statistics:Click here
Fusion of 2 black hole ...a perspective 2007-10-09 08:29:00 black hole black hole (blàk hÖl) noun 1. An extremely small region of space-time with a gravitational field so intense that nothing can escape, not even light. 2. A great void; an abyss: The government created a bureaucratic black hole that swallows up individual initiative. Black Hole Black Hole, theoretical object of extreme density and with a gravitational field so strong that nothing, including electromagnetic radiation, can escape from it. It therefore appears totally black. In 1994 astronomers using the Hubble Space Telescope found the first convincing evidence that a black hole exists. They found that an object of 2.5 billion to 3.5 billion solar masses must be present at the center of the galaxy M87. The black-hole concept was developed by German astronomer Karl Schwarzschild on the basis of German-American physicist Albert Einstein's theory of general relativity. According to general relativity, gravitation severely modifies space and time near a black hole. Time slows down
controversial question in relativity. 2007-10-09 08:26:00 Harvey Brown thinks that most philosophers are confused about relativity. Most centrally, he thinks they're confused about the relativistic effects of length contraction and time dilation. In this important book, he aims to set them straight. Brown takes sides in a debate about the explanatory role spacetime plays. (Although Brown repeatedly expresses solidarity with those who deny that spacetime exists, all parties to this debate are substantivalists -- they accept that spacetime exists. So Brown, too, accepts this view, for purposes of his argument). According to (what Brown alleges is) the dominant view among substantivalists, the geometrical structure of Minkowski spacetime plays some role in explaining why moving rods shrink and why moving clocks run slow. Brown rejects this view. He asserts, instead, that in order to explain why moving rods shrink we must appeal to the dynamical laws governing the forces that hold the parts of the rod together. The geometry of Minkowski spacetim
Graphite and tungsten,which is the one with less resistance to electricity? 2007-10-08 06:47:00 First I searched on "resistance materials" and found a chart that includes tungsten, from which I found that the resistivity of tungsten is listed as 5.6x10-8 ohm-meters. I then did a separate search on "graphite resistance" and found a table listing the resistivity of graphite as 7.8x10-6 ohm-meters. Materials with lower resistivity are better conductors, so from these data I conclude that tungsten is a better conductor than graphite Read more:electricity
, Graphite
In the energy level diagram of lasers the energies are marked in +ve value 2007-10-08 06:44:00 The energy level
diagrams in general should be negative as per the derivation ofenergy of nth orbit. then how is this possible? let's establish you are right-the most common definition of the energy of electrons in an atom or molecule is negative. The reason for this is as follows. Imagine the entire universe were empty except for a single electron. It would make sense to define that such an electron has an energy of 0, as there are no particles pulling on this electron. Now, imagine a proton exists on the other end of the universe. The distance between the two would be so large that the electric field [1] would be negligible, and the same would be true for the for the resulting energy. Now, imagine the electron moves closer and closer to the proton. The electric field strength increases, and the electron gains velocity. This increases the kinetic energy [2] of the particle. Now, this kinetic energy must come from somewhere, and in fact it is coming from the electric field between the
Energy to Matter under the Hood? 2007-10-06 10:47:00 I have completely discharged a lead/acid battery. I have used the appropriate charger to bring it up to full capacity. It weighs more, right? How much of the weight difference is energy converted to matter, if any? How much weight would I have to pay for a balance to measure that difference in mass?---------------------------------------Yes, it weighs more. It is all energy converted from electrical to chemical form, manifesting itself in the binding energy of the matter. It is not really correct to speak of energy being converted to matter here; it s just changing form from electricity to chemical. Read more:Energy
What are the chances of Pluto and Neptune crashing into each other? 2007-10-06 10:45:00 Virtually zero. Quoting from the text "The Solar System" by Encrenaz andBibring, (1990) "...Pluto
never comes closer to Neptune
than 2.5 thousandmillion kilometers... The fact that the periods of Neptune are in a simpleratio is the result of a dynamical resonance that has been discoveredrecently, and which corresponds to a stable state: any modification of thetrajectory under the influence of an external perturbation would be followedby a return to the present state of equilibrium." Read more:chances
, crashing
"Goldilocks" Zone for our Solar System 2007-10-06 10:37:00 What is a clear way to explain to students why the moon appears to be different sizes when viewed from Earth? Is there a fun way to model this for kids as well?---------------------------------------Dear Colleen,Although the Moon does vary in size from perigee to apogee (closest and farthest points to Earth in the Moon;'s orbit) I am not sure of how to illustrate this to children. While it is very hard to see the change in the size of the Moon as it moves round Earth, the change is obvious during solar eclipses. In an annular eclipse the Moon, at apogee, is smaller than the apparent diameter of the Sun and we see an annular or "ring" eclipse. Near perigee, the Moon is bigger and we see a total eclipse. Read more:Solar
, System
Wave Nature of Electrons 2007-10-03 08:08:00 Question: When wave nature of electron is being talked about, doesit mean that the electron moves in the form of a wave (that is,transverse)?---------------------------------------Shreya,It means that the electron has a frequency and a wavelength. A beam ofelectrons can produce interference patterns based on these wavequalities. It is not a particle vibrating like a wave. When behavinglike a particle, an electron has a clearly defined position and path.When behaving like a wave, it does not.
Electron Retracing Orbit 2007-10-03 08:07:00 Question: Will an electron, in an orbit with other electrons, ever travel along the same path twice or will it travel in a chaotic path which will eventually cross every single point in that orbit without ever travelling along that identical path?-------------------------------------------The flippant answer is "none of the above". It is not incorrect to think of electrons in atomic or molecular orbitals as planets orbiting the Sun. Electron
s obey quantum mechanics, while planets obey Newtonian (classical) mechanics [more or less because frequently simplifying assumptions are made about ignoring the gravitational effects of all the other planets. The two are very different.Electrons behave more like waves when confined to stable atomic/molecular states, but even this picture is incomplete, because the "waves" are not like throwing pebbles in a pond.Quantum mechanics only allows us to compute the "probability" that an electron will be at a point in space, and it really is not a "point" Read more:Orbit
How does gravity get out of a black hole? 2007-10-01 08:52:00 Question: How does gravity get out of a black hole? If gravity is mediated by a particle, say graviton, and the particle is subject to the usual limitation that nothing can travel faster than light, how do gravitons get across the event horizon? The part of the gravity of a black hole that is due to stress of space time outside the event horizon can certainly be mediated by gravitons without them needing to exceed the speed of light, but that just postpones the question: Why is space time stressed outside the event horizon, if gravitons cannot escape from it? Do they perhaps escape by Hawking-Penrose radiation? That does not seem right, because the intensity of Hawking-Penrose radiation decreases with increasing mass of the black hole.---------------------------------------Like I have said before, gravity and quantum mechanics have yet to be reconciled, and I think your question points out one possible place where reconciliation maybe difficult. I am sure there are resolutions fo
Flames and Zero Gravity 2007-10-01 08:51:00 Question: If an astronaut is in a space station at zero g's, and he strikes a match, how will the flame burn (in what direction) assuming an atmosphere similar to that on earth?---------------------------------------The flame would be mostly spherical since there is no gravity. But that means there would be no convection either, so the flame extinguishes itself fairly quickly. I think this has been demonstrated on one of the space shuttle flights. Read more:Flames
How to determine the direction of Probability Amps? 2007-10-01 08:47:00 Question: How do physicists determine the direction of probability amplitude for all types of light? I know that red light has a rotation of about 36,000 times per inch traveled. Does this have any relation to the frequency of this light?---------------------------------------Yes, your number 36,630 is the number of wavelengths of red light in an inch. The wavelength times the frequency is equal to the speed of light, so there is an indirect relationship to the frequency. For my number I assumed that the wavelength of red light is 7000 angstroms. The frequency would be 4.2 times 10 to the 14th power. Probability amplitudes are something different.Sam Bowen====================================================================The relation between the wavelength of light and its frequency is given by: wavelength * frequency = speed of light (=300,000 km/second). So, for visible light, which covers wavelengths from 400 to 700 nanometers (4 to 7 X 10^-7 meters, or 1.5 to 2.7 X 10^-5
Properties of Space Between Subatomic Particles 2007-09-29 10:15:00 Question: What are the properties of the space that exists betweensubatomic particles, and how does it affect the particles?---------------------------------------This is loaded question! No fair! :)Put simply, there is not just empty area between particles. The particlesthemselves actually are not just particles -- they actually spread/smear out-- and there are many other things that can make an appearance besideprotons, electrons, and neutrons. For more details, read on.With really small spaces, smaller than atoms, the common view of hard, solid"particles" turns out not to work too well. Scientists have learned thatparticles are not quite like the 'hard spheres' you might imagine. In factparticles in many ways are more like 'smears' that spread over lots oflocations all at once. I tell you this because an atom is not like a solarsystem -- atoms are not like planets revolving around a star. An atom ismore like a bunch of overlapping smears, whose positions are not exact (thinkof a Read more:Properties
, Space
neutrinos can pass through normal matter several light-years 2007-09-29 10:14:00 Question: According to Astronomy Collector's Edition (January 2007p.44), "neutrinos can pass through normal matterseverallight
-yearsthick"; however According to Astronomy Now (June 2005 p.65), "theyusually travel through thousands of kilometers of solid matterwithout interacting with it"; finally According to Curt Suplee'sPhysics in the 20th Century, "they interact so weakly with matterthat most shoot right through several million miles of lead". Sincea light-year is approximately 10 trillion km, there seems to bequite a discordance in what people write, because 10 trillion km >>1 million km of lead >> 1 thousand km of solid matter. So which isit? And how do scientists calculate the neutrino penetration depth?---------------------------------------Thierry,Actually, all three are correct. You must look very closely at thewording.First, "neutrinos CAN pass through normal matter several light yearsthick". Send a large beam of neutrinos through normal matter severallight years thick.
I have a question involving magnets and force. 2007-09-29 10:13:00 Question: I have a question involving magnets and force. I could not find the answer anywhere and do not quite know if I can use logic to answer. I have two neodymium magnets and each magnet has the ability to pick up and object 10 pounds. So if you used both together it could pick up an object 20 pounds. Now if I placed one of them on a table and then forced the other on top so they would repel and released it, the one on top would shoot off. My question is that when I release it will it fly off as a result of 20 pounds pushing it up?----------------------------------------------------You have a number of intertwined things going on in your "thought" experiment. I am not knocking "thought experiments" even Einstein himself used them magnificently in his many contributions to physics. I am sure I do not cover them all, but here are some of the "conditions" and possibilities.Assume the two magnets are ellipsoids of revolution, magnetized along the "long" axes, constrained in a cylindri
Do phone books burn? 2007-09-27 09:37:00 way to burn a telephone
book is with an oxyacetylene torch.Extreme heat will carbonise a phone book.But if you want to see a FLAME (red hot carbon particles rising from the book) you must get OXYGEN to the bit of the book that is supporting the flame. The easiest way to do this is to separate the pages (in air)
How can nanoscientists pick atoms 2007-09-27 09:36:00 People doing nanotechnology are often described as ‘moving atoms about’ e.g. with ‘tweezers’e.g. in newspapers. Also, images from STMs that I've seen on the net make atoms appear as fairly stable round objects. But what you can see as the atom’s outer shell should really be the most distant electron from the nucleus (never mind the other theories from quantum physics about the funny behaviour of matter at this level). So how can nanoscientists pick atoms up and move them about when they are not actually ‘hard objects’?why atoms appear so nicely spherical. There are two different ways to think of the electron: particle-like and wave-like (which I'll ignore here to avoid the "funny behavior", as you've aptly described it). Let's consider the particle description. You may be visualizing the atom via the Bohr model (i.e. as solar-system-like), with a large nucleus in the center, and a little particle sitting out a bit from the nucleus. From this mental image, you might ex
Why doesn't a copper disk spinning cause an APPRECIABLE magnetic field? 2007-09-24 12:06:00 Normally, a piece of copper is electrically neutral, which means itcontains the same amount of positive charge and negative charge. Thecrystal lattice of copper, which carries positive charge, is like theskeleton. The free electrons move around the crystal lattice. When there iscurrent in the copper, the electrons move in one direction but the crystallattice does not move, the magnetic
field caused by each electron sumtogether so you can observe a total magnetic field.However, if you move the entire metal, both crystal lattice and electronsare moving, so they all generate magnetic field. However, since they movein the same direction but have different signs of charge, the magneticfield generated by them will cancel each other, therefore you cannotobserve the magnetic field.References[1] Structure of metal http://www.teachersdomain.org/resources/phy03/sci/phys/matter/metal/index.html[2] Magnetic field of moving charge, http://academic.mu.edu/phys/matthysd/web004/l0220.htm Read more:spinning
What happens when supermassive blackholes pull in all matter? 2007-09-24 12:04:00 Supermassive black holes are found in the very centers (the nuclei) oflarge galaxies. We don't know of any supermassive black holes that arefound elsewhere, so these are all quite far apart. The (centers of) ourMilky Way galaxy and the Andromeda spiral galaxy are over 2 million lightyears apart.In general, black holes are not giant vacuum cleaners that suck in allmatter
. They will absorb anything that lands on them, but black holes arequite small in diameter and so they can only absorb a small amount ofmatter at a time. For example, the black hole at the center of the MilkyWay has a mass of about 2 million times the mass of the Sun. That soundslike a lot, but it has taken the entire history of the Universe (about 14billion years) for the black hole to grow to that mass. At this averagerate, it takes 7000 years to absorb as much mass as the Sun has.Now galaxies do sometimes merge, and the black holes at their centersprobably merge also, but the rate of mergers is also low. So it
Can an electron interference pattern of some kind be generated? 2007-09-22 03:22:00 This is a difficult question to answer, because it is not clear to me where you wish to apply the oscillating electric field (before or after the slits?), or for that matter, what you are trying to accomplish by this. That having been said, I think that the result of putting an oscillating electric field into a double-slit experiment setup would be to partly or completely destroy the interference pattern. The double-slit experiment is a measure of the spatial, or time-independent wavefunctions of the electrons. To do this, the electrons arriving at the slits should all have the same energy. Once they pass through, the time-independent wavefunctions from the two slits interfere with each other to produce the characteristic interference pattern. Now, if you put an oscillating electric field between the source and the slits, the electrons will arrive at the slits with different energies depending on the time. If the oscillating field is after the slits, the electrons could arrive at the s
Does dark matter have a measurable effect upon the orbits of planets? 2007-09-21 12:10:00 Dark matter
represents about 23% of the total mass-energy of the Universe, or about 5.8 times the mass of ordinary matter. Dark energy, an entirely different thing, makes up the remaining 73%.Dark matter doesn't impact the orbits of planets significantly. Because we don't know how to detect dark matter directly, it is hard to know its exact distribution. Most of the mass of local dark matter is located in a halo surrounding our galaxy (likewise for all other galaxies), but whether that means we are in an area devoid of dark matter or not isn't certain. But even if there is dark matter around us, its density would be both low and nearly uniform- imagine a thin gas made of dark matter. The orbits of the planets are dominated by the large mass concentration of the Sun (and to a small extent, Jupiter). Neither a thin gas of dark matter around us, nor the much greater mass found outside our visible galaxy, can affect planetary motion. Read more:effect
Does dark matter have a measurable effect upon the orbits of planets? 2007-09-20 09:07:00 Dark matter
represents about 23% of the total mass-energy of the Universe, or about 5.8 times the mass of ordinary matter. Dark energy, an entirely different thing, makes up the remaining 73%.Dark matter doesn't impact the orbits of planets significantly. Because we don't know how to detect dark matter directly, it is hard to know its exact distribution. Most of the mass of local dark matter is located in a halo surrounding our galaxy (likewise for all other galaxies), but whether that means we are in an area devoid of dark matter or not isn't certain. But even if there is dark matter around us, its density would be both low and nearly uniform- imagine a thin gas made of dark matter. The orbits of the planets are dominated by the large mass concentration of the Sun (and to a small extent, Jupiter). Neither a thin gas of dark matter around us, nor the much greater mass found outside our visible galaxy, can affect planetary motion. Read more:effect
: Can an electron interference pattern of some kind be generated? 2007-09-20 09:06:00 This is a difficult question to answer, because it is not clear to me where you wish to apply the oscillating electric field (before or after the slits?), or for that matter, what you are trying to accomplish by this. That having been said, I think that the result of putting an oscillating electric field into a double-slit experiment setup would be to partly or completely destroy the interference pattern. The double-slit experiment is a measure of the spatial, or time-independent wavefunctions of the electrons. To do this, the electrons arriving at the slits should all have the same energy. Once they pass through, the time-independent wavefunctions from the two slits interfere with each other to produce the characteristic interference pattern. Now, if you put an oscillating electric field between the source and the slits, the electrons will arrive at the slits with different energies depending on the time. If the oscillating field is after the slits, the electrons could arrive at the s
Habitable zones around binary stars. 2007-09-17 06:54:00 HD 98800 and HD 188753 have made me curious as to how binary star habitablezones work. Could 2 K type stars
have a habitable zone similar to a single G2star? Would 2 G2 stars' habitable zone be much less or more than a single G2star? Is there an equation for generalizing this? (ie: star a is mass x, star bis mass y, they are c distance apart, treat as 1 star of mass z to determine hz)Unfortunately I could not find a simple answer to your question. In order to have an habitable zone we need to consider first the possibility of forming a planet there and then the possibility of forming life. It is believed that stars form at the centers of rotating disks in a cloud of interstellar gas and dust. Friction in the disk (and gravity!) makes the dust and gas fall to the center to form the star. Planets are believed to form from the remains of the disk. It is possible that two disks form close enough to form a pair of stars that rotate around each other. This is called a binary star system or
Where is Alpha Centuri in accordance with the galaxy Andromeda 2007-09-17 06:52:00 Alpha Centauri is a star in our own galaxy that is about 4.5 light years away, while Andromeda is a different galaxy that is about 2.5 million light years from us. They are not even close to each other in the "map" that we call our sky, which you can see by looking at the right ascension and declination numbers at the Wikipedia pages that are pointed to by the first two hot links above. Read more:Alpha
Six Dimensions and Fiction 2007-10-16 02:20:00 Question: How do theories of six-dimensional geometry apply to time? Is there any validity to the transporters they created for "Star Trek: the Next Generation"?There are theories of the universe that involve dimensions higher than 3 or 4, but they usually do not have any effect on time. These higher dimensions just increase the spatial dimensions, and only in a very minor way. Science fiction, of course, does not have to rely on the silly restrictions of modern physics theories. In principle, one could build some kind of "transporter". However, the only kind I can think of would be more like "duplicators", which would produce a second copy of the object being transported, rather than actually do the transporting. This of course creates all sorts of philosophical problems which Star Trek has chosen not to worry about.====================================================================A recent discovery in quantum mechanics has shown that there may be a sense in which "transporti Read more:Dimensions
, Fiction
Mass and Energy to Gravity 2007-10-16 02:19:00 Question: Every particle that has mass generates (or at least is associated with) its own gravitational field. Matter, can be converted into energy. When that happens, what becomes of the gravitational field that was associated with that quantity of matter that has become energy?It turns out that gravitation does not depend directly on mass - it depends only through the energy (and momentum) of the matter involved. If the matter changes in some way to reduce its rest mass, this has no effect on the total energy (or momentum) of the system, although it would certainly change the energies and momenta of the individual particles making up the matter in question. This would have a short range effect on the gravitational field, but only in the way one would expect an explosion to have an effect. There would be no long-range effect because there is no net change in energy of the gravitating matter. Read more:Energy
Flame in Space 2007-10-16 02:15:00 Question: If an astronaut is in a space station at zero g's, and he strikes a match, how will the flame burn (in what direction) assuming an atmosphere similar to that on earth?The flame would be mostly spherical since there is no gravity. But that means there would be no convection either, so the flame extinguishes itself fairly quickly. I think this has been demonstrated on one of the space shuttle flights. Read more:Space
How does winter solstice work? 2007-10-15 02:06:00 Due to the rotation of our planet around the Sun, the position of the Sun in the sky changes, in the north-south axis, over the course of the year due to the changing orientation of the Earth's rotation axes with respect to the Sun. The dates of maximum tilt of the Earth's equator correspond to the summer and winter
solstice, and the dates of zero tilt to the vernal and autumnal equinox. In the northern hemisphere, the Winter solstice is day of the year (near December 22) when the Sun is farthest south
Why does the earth move like the way it does and will it ever change in the future 2007-10-15 02:06:00 Why does the earth move like the way it does and will it ever change in the future because me and my brother have a bet i say that it will probbly never and he says it willThe answer to your question starts with the Big Bang. Matter spun off of this original explosion (much like water spins in smaller circles when you swirl your hand through it). Scientists believe that the solar system was formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star (called a supernova). This explosion made waves in space which squeezed the cloud of gas and dust. Squeezing made the cloud start to collapse, as gravity pulled the gas and dust together, forming a solar nebula. The planets and moons were formed from this solar nebula. The Earth and other planets continue to spin unless acted on by an outside force (a big comet hitting the planet, etc).
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