Where's the Edge of the Universe?
The time zones we use today are based on those adopted by North American railroads on November 18, Those zones recognized the meridian passing through Greenwich, England, as zero degrees longitude, as did an international conference in Carlene Stephens curator of time collections, American History Museum. How does a lightning bolt lasting a second or less produce a thunderclap lasting ten seconds or more? Richard Pearce Brattleboro, Vermont. A lightning bolt heats the air so that it expands at tremendous speed—fast enough to create a shock wave that travels outward at the speed of sound.
That shock wave is what we hear as a thunderclap. When the shock wave hits the irregular ground surface, some of the energy is reflected to create other waves; these we hear as a low rumbling after the clap. Andrew Johnston geographer, Air and Space Museum. Jellyfish do not have a brain or centralized nervous system, but they do have sensory structures and sensory cells that make up a nervous system.
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This system, which varies in complexity from species to species, allows jellyfish to react to chemical and physical cues in their environment. Allen Collins invertebrate zoologist, Museum of Natural History. It's your turn to Ask Smithsonian. In 10 trillions years roughly times the current age of the universe or CAU , the remnant white dwarf will be a crystal about five degrees above absolute zero.
Ironically enough, this also is about the time that it will take most Red Dwarves which are simply smaller normal stars to become white dwarves. In other words, in a thousand million years, most of the stars left in the universe will be red dwarfs and white dwarfs. The Sun is close to the upper limit masswise for becoming a white dwarf it is actually not quite an average star, but is instead perhaps about one and a half standard deviations on the big side. Of course such a blue carbon dwarf would weigh in at something like 10,,,,,,,,, ,, carats, and would be so dense that something the size of a wedding band setting would weigh as much as the Himalaya mountain range.
As a consequence, neutron stars are very small but very, very heavy. Like a ballet dancer doing a pirouette, this translates into an angular momentum on the order of thousands of revolutions a second. Moreover, because most stars have clear electromagnetic fields, these neutron stars generate immense magnetic fields that show up as brilliant jets, often several hundreds of light years long. One step up from neutron stars are quark stars. In addition to this, an additional kind of quark star might be made up partially or fully from strange quarks, which are potentially stable and which converts other quarks to strange quarks.
Strangelets have actually been proposed as a way of creating planet destroying bombs, as even a small amount of strange material would eventually turn an ordinary planet into amorphous strange goo within a disturbingly short amount of time months or even weeks. The final beast in the exotic star zoo is of course the Black Hole.
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Black holes are from type IA supernovas, but they can also form from accretion which may in fact be the primary way of making them. Black holes have been postulated since Einstein, and such scientists as Chandrasekhar, John Wheeler and the late Stephen Hawkings have expended considerable research on both their origins and their fate. Black holes do not have infinite gravitational attraction. They have a very high density, and very likely look, within their event horizon, like very dense quark stars.
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What is so fascinating about a black hole, though, is that event horizon. Once you pass this event horizon, no amount of energy will let you cross back over the event horizon in the other direction. It is not the actual radius of the star.
Instead, the event horizon radius called the Schwarzchild Radius is proportional to the mass of the stellar object, which raises the possibility that a neutron star close to the minimal side of a black hole more than 2. Intriguingly, that still makes the event horizon only about a light year or so across, and the actual density within at least parts of the event horizon might well be roughly comparable to the density of space near Earth. Typically a black hole will only really be visible when it is eating another star, and then primarily by the accretion disk and the magnetic jets as powerful magnetic fields move charged particles to the poles.
Additionally, there have been theories proposed that a black hole, if both charged and spinning, that could effectively expose the singularity, the point of theoretically infinite density that marks the center of the black hole. Most science fiction fans would wish that Einstein too was wrong or at least was just not sufficient at the extremes of our knowledge , because it would imply that faster than light travel was possible.
Where's the Edge of the Universe?
Yet ultimately this comes down to the emerging conflict between how the quantum world works and how relativity works. He was the first person to calculate that the atmosphere around this altitude becomes too thin to support aeronautical flight, since a vehicle at this altitude would have to travel faster than orbital velocity to derive sufficient aerodynamic lift to support itself. An atmosphere does not abruptly end at any given height, but becomes progressively thinner with altitude.
Also, depending on how the various layers that make up the space around the Earth are defined and depending on whether these layers are considered part of the actual atmosphere , the definition of the edge of space could vary considerably: An aircraft only stays aloft if it constantly travels forward relative to the air airspeed is not dependent on speed relative to ground , so that the wings can generate lift.
The thinner the air, the faster the plane must go to generate enough lift to stay up. The amount of lift required at any given point can be calculated by the lift equation: An orbiting spacecraft only stays in the sky if the centrifugal component of its movement around the Earth is enough to balance the downward pull of gravity.
If it goes slower, the pull of gravity gradually makes its altitude decrease. The required speed is called orbital velocity , and it varies with the height of the orbit. For an airplane flying higher and higher, the increasingly thin air provides less and less lift , requiring increasingly higher speed to create enough lift to hold the airplane up.
It eventually reaches an altitude where it must fly so fast to generate lift that it reaches orbital velocity. In practice, supporting full weight wouldn't be necessary to maintain altitude because the curvature of the Earth adds centrifugal lift as the airplane reaches orbital speed. However, the Karman line definition ignores this effect because orbital velocity is implicitly sufficient to maintain any altitude regardless of atmospheric density. The Karman line is therefore the highest altitude at which orbital speed provides sufficient aerodynamic lift to fly in a straight line that doesn't follow the curvature of the Earth's surface.
An international committee recommended the km line to the FAI, and upon adoption, it became widely accepted as the boundary to space for many purposes.
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