Get a Straight Answer

Hi David

    I am quite interested in physics in general, mainly quantum physics and the likes. One thing that to this day baffles me about physics is the whole concept of energy.

    The thing I can't understand is that if you had a room temperature super-conductor (as I am aware, they haven't come up with one yet) you could have a device that produces either a repulsive or attractive force, just whilst it sits in your back garden, no extra energy required. So how is it able to produce this repulsive/attractive force without ever needing energy.

    And how can the universe be expanding on limited energy and why is it not slowing down there further out it gets (Surely the further out it goes the energy has a larger void to cover so should dissipate), How do black holes consume so much energy and release none (Where does the energy go to if energy can't be created or destroyed?)

    How does the Big Bang Theory work if with limited energy the universe started from something, that assumes that everything in the Universe was created from nothing, which could mean it is possible to create energy from nothing.

    Any thoughts on what I have dicsussed would be most appreciated.

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    Nature owes us no explanations! WE are the ones who sometimes need change our thinking in light of observations. Nature's phenomena follow their own rules, not ours, and it's OUR job to understand them.

    Ancient Greeks believed (and Copernicus still subscribed to that belief) that heavenly bodies moved in circles, because the circle had perfect symmetry, and Nature could not be anything short of perfect. Then Kepler introduced ellipses, Newton proved orbits had to be elliptical, and astronomy adjusted to a new view.

    In the 19th century, science knew that material objects (sticks, stones, etc.) were localized, while waves filled space. Today we know electrons (say) can behave like waves or particles, depending on circumstances, and Schroedinger's equation bridges the gap between their extreme behaviors. Electromagnetic waves sometimes act as photons--particles of zero mass. Physicists had to adjust their views again.

   . Now about those superconductors. In everyday life, almost any physical process associated with energy transfer always suffers a loss. Motion loses energy to friction, current flow in a wire encounters ohmic resistance, and if you charge an electric battery, you can never recover all the energy invested. That happens because whenever an energy conversion process involves an large number of atoms, at least part of it that energy ends up shared by the atoms as heat. It's as if the energy had to pay a sales tax.

    Processes involving single atoms are often exempt from such "taxation." The Bernoullis (I think) were the first to explain the gas laws by assuming that a gas consists of zillions of molecules or atoms, little spheres which fly through space and collide with each other. Their collisions are perfectly elastic, never losing any energy. Some larger-scale quantum phenomena--e.g. currents in a superconductor--also behave like that, they may not involve a single particle but rather a single quantum state, which seems just as good. And a bar magnet that has been magnetized stays magnetized indefinitely, with no energy input.

    Since all things on the earth rotate with it at a constant speed, including the atmosphere (generally), how do spacecraft "recalibrate" themselves to the rotation of the earth (1000mph) upon reentry? When does it happen? What effect does it have on the passengers? I am assuming that it happens before they touch the earth since the atmosphere itself moves with the earth's rotation. Thanks for your help!

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    That is why the shuttle is launched eastwards from Cape Canaveral: its orbital velocity is measured relative to space and depends only on the Earth's gravity, which is the same whether the Earth rotates or not. Therefore, an eastward launch from Cape Canaveral already has an initial velocity in the right direction, and needs only add the remaining difference.

    But then I had a dream about it and awoke this morning with the theory that if a massive black hole opened a wormhole and sucked us right through the wormhole and into its center. Both teachers I told this to said I shouldn't worry about that (I never worry about drowning, but the supernatural is another story). But what do you think--is it at all possible? What would happen if we did get sucked in? Would it be, as my friend would call it, "an incredibly painful and excruciatingly long death" for everyone, or would it just me instant blackness? And are we at the mercy to this supposed black hole at the center of the galaxy? If so, how long does our planet have? How fast is it carrying everything in?

Okay. I'll stop bugging you now.

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    I looked up wormholes on the web, on "Wikipedia." There exists a lot of theoretical speculation, but I found nothing positive. Maybe it should be filed for now under science fiction, in the realm of things we cannot prove to be impossible, even though they have yet to be observed.

    I would like to find new ways to produce energy, like solar panels do, by converting some natural form of energy into electrical energy. I am enrolled in my first semester of Mechanical Engineering and working as an RN in a local hospital.

    I am curious as to your advice on what I should be studying. My math is only at the level Of Algebra I (I haven't had any math really in 7-8 years). Should I stay in Engineering? If so what field? Mechanical or electrical? Or should I go for a physics degree.

    I would greatly appreciate your guidance, or else, ask others in your dept for their input and please write me back. I also thought about going back to school to get a degree in biology to do research in finding cures or vaccines for AIDS, Cancer, Herpes...Which I believe are all related because they have to do with changes in DNA/RNA.

    Can you please give me some assistance. The tests I have taken say Engineering, then Medicine as a second choice. My family has a heavy background in electronics. I like classes like Chemistry, Physics, and Biology.

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    I hate to sound discouraging, especially in face of your enthusiasm, but there seems to exist a huge gap between where you are and what you are trying to reach.

    Maybe I share some of the blame: the web pages I have created--carefully avoiding complex math and theory--may have done too good a job, in making the complicated seem simple to you. Front-line science is not simple, the simple stuff was all solved long ago.

    When a photon from the sun hits the surface of the earth, it may be reflected (in which case its energy goes into making a new photon of the same wavelength) or it may be absorbed. The energy from photons that are absorbed goes into heating the earth. The earth takes some of the absorbed heat and generates new photons in the infrared part of the spectrum.

    Can those photons go through the atmosphere and into space, or are they trapped by the atmosphere? If they go into space, what happens to the temperature of the earth? If they're trapped, what happens to the temperature of the earth?

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    Neglecting the ellipticity of the Earth, the length of the equator would be 40,000 kilometers (ellipticity adds about 74 km), making one degree of longitude 40,000/360 = 111.3 kilometers.

    The average radius of the Earth is R = 6371 km (a few less than the 40,000 km value gives). At latitude L, the length of a line of latitude is 6.2832 R cosL (the factor is 2π), so one degree is (6.2832 R/360) cos L or about 111 cosL kilometers. As the latitude L increases, cos L gets smaller and smaller, and for people walking around the south pole (as some do at the South Pole Scientific Station) each degree is but one small step.

Follow up:

    One dgree also contains 60 minutes of arc, making one minute of latitude equal to about 1.85 kilometers. That distance is defined as a "nautical mile", and a velocity of one nautical mile per hour is "one knot", the common unit for measuring speed at sea.

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    Pressure is force per unit area (look up in the dictionary; example: pounds per square inch, the PSI of tire pressure). So given an area A and a pressure P, the force on it is AP (A times P).

    Suppose you have a cube with side equal to one unit (inch, or centimeter, or meter--whatever you work with; it helps to make a drawing here). The area A of each side is then one square unit. Suppose also that he pressure P₁ in the surrounding fluid (air, water or whatever) on the cube's right side is higher than the pressure P₂ on its left. So the force AP1 on the right side is greater the force AP2 on the left side. The greater force overcomes the weaker one and pushes the cube from right to left, from high pressure to lower one. That is a general rule.

    The force which moves air from hot to cold is BUOYANCY--the tendency for lighter fluids to float up when surrounded by heavier (denser) ones--for example, oil floats to the top of water. You can prove (look up in a textbook) that with a cube (say) of light fluid immersed in a denser one, the net pressure P₁ on the bottom is larger than the pressure P₂ on the top. So it rises.

    In the atmosphere, sunlight heats the ground, causing air there to heat up, too. Heated air expands and becomes less dense, and therefore rises (like a hot air balloon). As air rises, it expands and cools down. Such processes operate in the atmosphere all the time, so as you go higher (into high mountains, for instance), the air is cooler. As a result, "freshly heated" air rises only until its surroundings are just as cool.

    It was then suggested that a Solar Magnifier could be stationed close to the Asteroid and by focusing the sun's rays at the Asteroid, burn a hole which would release energy pushing the Asteroid in to a different orbit away from Earth.

    I then had the idea of an Ion Rocket landed on the surface of the Asteroid and used to gradually increase the push away from Earth's orbit, perhaps completely out of the Solar System. Could an Ion Rocket be used for such an application? Would it be to cost prohibitive? If needed, could not the Sun's rays be used to power the Ion Rocket?

    This is what brought me to your site for research on Ion Rockets. Your thoughts on this would be greatly appreciated as the program did not even mention it.

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    A nuclear explosion near an asteroid would vaporize the region closest to it, and the vaporized rock would stream away from the asteroid. By Newton's law, the force moving those vaporized molecules away from the asteroid would be exactly matched by a force pushing the asteroid in the opposite direction. Whether the asteroid is hard or soft makes no difference: the momentum transmitted to the asteroid is the same.

    If that would be enough to save the Earth depends on circumstances. Even small asteroids are very massive, and their orbit would probably be modified only slightly. However, if one can intercept an asteroid years before its expected impact on Earth, that may be enough. Of course, even then it would still be in an orbit which can some day again come close to Earth (unless one can make it hit the Moon).

    If the asteroid material is too loose, the vapors released (they blow in all directions) may also blow some of it apart. Indeed, a bomb dug into the asteroid may conceivably blast it apart completely, so instead of a single solid impact with Earth, we may end up with multiple impacts by many smaller objects. These may perhaps burn up in the atmosphere, but would still radiate a lot of heat. Whether that makes the impact less destructive or more so, I am not sure.

    A "solar magnifier" does not exist, and I cannot imagine it. A large light solar mirror will be quickly pushed away by sunlight pressure... and anyway what would it accomplish? If you want to equal the effect of a nuclear bomb by evaporating part of the surface, you need deliver a comparable amount of energy. Hard to imagine!

    Meteorites arriving near the observer would not be reddish or orange--by the time they cool down to emit that color, they are already quite dim.

    If I were to guess, you may have seen a flare dropped by a military airplane or fired from a ship, as part of some training exercise or a rescue effort. Flares are very bright and are meant to illuminate large areas below, and they descend slowly by parachute. They burn with a bright, white light (produced by magnesium, or by some other burnable metal, as in a firebomb), but since the one you saw was close to the ground, it was probably far off--perhaps beyond the horizon, made visible only by the bending of its light in the atmosphere.

    The problem is that the Sun and the solar system are moving through space towards the "solar apex" (look it up) at about 20 km/sec. That is more than the orbital velocity around any distant object. Of course, that distant object could move at the same velocity, too.

    In my estimation, chances are very much against it. Another clue may come from tracking distant space probes: do they indicate an influence other than the gravity of the Sun and the known planets? It turns out that a small discrepancy exists with the Pioneer spacecraft, but no one has yet mentioned another star as its source.

    Of course, life would quickly end. After being burned crisp by the energy released from the collapse, Earth would get very, very cold.

    My question is why is it the Fraunhofer lines which shift, as I would have thought the atoms in the atmosphere of both Earth and the star would absorb the same frequency of light regardless of the movement of the star or Earth? I asked my physics teacher and he did not know the answer.

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    It would, if the dark absorption feature is caused by gas at the star. It would not, if it is caused by absorbing gas in the atmosphere of the Earth, which is one of the ways we can tell apart absorption that happens THERE from the one happening HERE.

    Again, physics adds some interesting details. You know that spectral frequencies are very, very narrowly defined. One Fraunhofer line due to calcium, for instance, has a wavelength 422.6742 nanometer, defined to 7 decimal figures. However, if you split sunlight in a spectroscope and look for spectral emission lines from various elements, you will find each covers a certain spread of wavelengths. One reason is the Doppler effect: the solar envelope is hot, which means its atoms have large random velocities. Some happen to be approaching us when they emit light, some are moving away, and the Doppler effect shifts their wavelengths in opposite directions. As a result, when the wavelength spread of a spectral line is examined (and instruments exist--interferometers--which do so very well) we get a sort of bell-shaped curve, peaking at the appropriate wavelength, but spread to both sides (a pressure effect can also contribute).

    However, there may be something interesting about this curve. Sometimes we see a dip right at the peak, because above that emitting region, there may be a cooler absorbing region (temperature may go down with height for a short distance before--on the Sun--it goes up again). The absorption line is narrower because, being cooler, it has less of a Doppler effect.

    Electromagnetic radiation is another name for light, and for wave phenomena which are similar to light but with longer or shorter wavelengths: radio, microwave, infra-red, ultra-violet, X-rays and gamma rays are all electromagnetic waves.

    So electromagnetic waves are the ONLY source (with a few exotic exceptions) through which we get information about the universe outside Earth.

    The astronomer Martin Harwit used this fact to ask, what is the maximum information such waves CAN give us about the universe? He made a chart of all the wavelengths, and the resolution we can get in each (how small and faint are the details we can see), and then pointed out where unobserved "gaps" remained. Most were in wave lengths which the atmosphere does not let through, so to fill them meant setting up observatories in space. NASA's "great observatories" programs tries to fill those gaps--for instance, the "Chandra" X-ray telescope.

    It said that just as a baseball loses kinetic energy and gains potential energy as it rises in its trajectory, the air molecules lose kinetic energy as they rise.

    Here is the actual quote:

"When the warm air rises, the speed of those air molecules slows down just like a ball that is thrown into the air slows down. The molecules convert their kinetic energy into potential energy when they rise into the air just like the ball did. And since temperature is a measure of kinetic energy, the lower kinetic energy means a lower temperature."

    But where you and I live, temperature drops with altitude for a simpler reason. The Sun heats the ground, and unless this heating were to continue indefinitely (to where the oceans would boil, etc...) that heat must be returned to space. It is a complex process, involving convection and also radiation, which is emitted, absorbed and re-emitted by greenhouse gases as it works its way up, until at about 10-12 kilometers (typically) this infra-red radiation can continue to space.

    In all these processes, heat flows upwards, and as we all know, heat only flows (unaided) from higher temperature to a lower one.