Hawaiis Volcanic Hot Spot

Hawaiis Volcanic Hot Spot Under the Hawaiian Islands, there is a volcanic â€Å"hot spot,† a hole in the Earth’s crust that allows lava to surface and layer. Over millions of years, these layers form mountains of volcanic rock that eventually break the surface of the Pacific Ocean, forming islands. As the Pacific Plate very slowly moves across the hot spot, new islands are formed. It took 80 million years to create the current chain of Hawaiian islands. Discovering the Hot Spot In 1963, John Tuzo Wilson, a Canadian geophysicist, introduced a contentious theory. He hypothesized there was a hot spot under the Hawaiian Islands - a mantle plume of concentrated geothermal heat that melted rock and rose up as magma through fractures under the Earth’s crust. At the time they were introduced, Wilson’s ideas were very controversial and many dubious geologists were not accepting theories of plate tectonics or hot spots. Some researchers thought that volcanic areas were only in the middle of plates and not at subduction zones. However, Dr. Wilson’s hot spot hypothesis helped to solidify the plate tectonics argument. He provided evidence that the Pacific Plate has been slowly drifting over a deep-seated hot spot for 70 million years, leaving behind the Hawaiian Ridge-Emperor Seamount Chain of more than 80 extinct, dormant, and active volcanoes. Wilson’s Evidence Wilson worked diligently to find evidence and tested volcanic rock samples from each volcanic island in the Hawaiian Islands. He found that the oldest weathered and eroded rocks on a geological time scale were on Kauai, the northernmost island, and that rocks on the islands were gradually younger as he went south. The youngest rocks were on the southernmost Big Island of Hawaii, which is actively erupting today. The ages of the Hawaiian Islands gradually decrease as seen in the list below: Niihau and Kauai (5.6 - 3.8 million years old).Oahu (3.4 - 2.2 million years old)Molokai (1.8 - 1.3 million years old)Maui (1.3 - 0.8 years old)Big Island of Hawaii (less than 0.7 million years old) and it is still expanding. The Pacific Plate Conveys the Hawaiian Islands Wilson’s research proved that the Pacific Plate has been moving and carrying the Hawaiian Islands northwest off the hot spot. It moves at a rate of four inches a year. The volcanoes are conveyed away from the stationary hot spot; thus, as they move farther away they become older and more eroded and their elevation decreases. Interestingly, about 47 million years ago, the path of the Pacific Plate changed direction from north to northwest. The reason for this is unknown, but it might have been because of India colliding with Asia at approximately the same time. The Hawaiian Ridge-Emperor Seamount Chain Geologists now know the ages of the undersea volcanoes of the Pacific. In the farthest northwest reaches of the chain, the underwater Emperor Seamounts (extinct volcanoes) are between 35-85 million years old and they are highly eroded. These submersed volcanoes, peaks, and islands extend 3,728 miles (6,000 kilometers) from the Loihi Seamount near the Big Island of Hawaii, all the way to the Aleutian Ridge in the northwest Pacific. The oldest seamount, Meiji, is 75-80 million years old, whereas the Hawaiian Islands are the youngest volcanoes - and a very small part of this vast chain. Right Under the Hot-Spot: Hawaii’s Big Island Volcanoes At this very moment, the Pacific Plate is moving over a localized source of heat energy, namely, the stationary hot spot, so active calderas continually flow and erupt periodically on the Big Island of Hawaii. The Big Island has five volcanoes that are connected together – Kohala, Mauna Kea, Hualalai, Mauna Loa, and Kilauea. The northwestern part of the Big Island ceased erupting 120,000 years ago, whereas Mauna Kea, the volcano in the southwest part of the Big Island erupted only 4,000 years ago. Hualalai had its last eruption in 1801. Land is continually being added to the Big Island of Hawai’i because lava that flows from its shield volcanoes is deposited on the surface. Mauna Loa, the largest volcano on Earth, is the most massive mountain in the world because it occupies an area of 19,000 cubic miles (79,195.5 cubic km). It rises 56,000 feet (17,069 m), which is 27,000 feet (8,229.6 km) higher than Mount Everest. It is also one of the world’s most active volcanoes having erupted 15 times since 1900. Its most recent eruptions were in 1975 (for one day) and in 1984 (for three weeks). It could erupt again at any time. Since Europeans arrived, Kilauea has erupted 62 times and after it erupted in 1983 it stayed active. It is the Big Island’s youngest volcano, in the shield forming stage, and it erupts from its large caldera (bowl-shaped depression) or from its rift zones (gaps or fissures). Magma from the Earth’s mantle rises to a reservoir about one-half to three miles under Kilauea’s summit, and pressure builds up in the magma reservoir. Kilauea releases sulfur dioxide from vents and craters - and lava flows onto the island and into the sea. South of Hawaii, about 21.8 mi (35 km) off the coast of the Big Island, the youngest submarine volcano, Loihi, is rising from the sea floor. It last erupted in 1996, which is very recent in geological history. It is actively venting hydrothermal fluids from its summit and rift zones. Rising up about 10,000 feet above the ocean floor to within 3,000 feet of the water surface, Loihi is in the submarine, pre-shield stage. In accordance with the hot spot theory, if it continues to grow, it might be the next Hawaiian Island in the chain. The Evolution of a Hawaiian Volcano Wilson’s findings and theories have increased knowledge about the genesis and life cycle of hot spot volcanoes and plate tectonics. This has helped to guide contemporary scientists and future exploration. It is now known, that the heat of the Hawaiian hot spot creates fluid molten rock that consists of liquefied rock, dissolved gas, crystals, and bubbles. It originates deep below the earth in the asthenosphere, which is viscous, semi-solid and pressurized with heat. There are huge tectonic plates or slabs that glide over this plastic-like asthenosphere. Due to the geothermal hot spot energy, the magma or molten rock (which is not as dense as the surrounding rocks), rises through fractures from under the crust. The magma rises and pushes its way through the tectonic plate of the lithosphere (the rigid, rocky, outer crust), and it erupts on the ocean floor to create a seamount or underwater volcanic mountain. The seamount or volcano erupts under the sea for hundreds of thousands of years and then the volcano rises above the sea level. A large amount of lava is added to the pile, making a volcanic cone that eventually sticks out above the floor of the ocean - and a new island is created. The volcano keeps growing until the Pacific Plate carries it away from the hot spot. Then the volcanic eruptions cease to erupt because there is no longer a lava supply. The extinct volcano then erodes to become an island atoll and then a coral atoll (ring shaped reef). As it continues to sink and erode, it becomes a seamount or guyot, a flat underwater tablemount, no longer seen above the water’s surface. Summary Overall, John Tuzo Wilson provided some concrete evidence and deeper insight into the geological processes above and below the surface of the Earth. His hot spot theory, derived from studies of the Hawaiian Islands, is now accepted, and it helps people understand some ever-changing elements of volcanism and plate tectonics. Hawaii’s undersea hot spot is the impetus for dynamic eruptions, leaving behind rocky remnants that continually enlarge the island chain. While older seamounts are declining, younger volcanoes are erupting, and new stretches of lava land is forming.

The Theory of Relativity and the Speed of Light

The Theory of Relativity and the Speed of Light One commonly known fact in physics is that you cannot move faster than the speed of light. While thats basically true, its also an over-simplification. Under the theory of relativity, there are actually three ways that objects can move: At the speed of lightSlower than the speed of lightFaster than the speed of light Moving at the Speed of Light One of the key insights that Albert Einstein used to develop his theory of relativity was that light in a vacuum always moves at the same speed. The particles of light, or  photons, therefore move at the speed of light. This is the only speed at which photons can move. They cant ever speed up or slow down. (Note: Photons do change speed when they pass through different materials. This is how refraction occurs, but its the photons absolute speed in a vacuum that cannot change.) In fact, all of the bosons move at the speed of light, so far as we can tell. Slower Than the Speed of Light The next major set of particles (so far as we know, all of the ones that arent bosons) move slower than the speed of light. Relativity tells us that it is physically impossible to ever accelerate these particles fast enough to reach the speed of light. Why is this? It actually amounts to some basic mathematical concepts. Since these objects contain mass, relativity tells us that the equation kinetic energy of the object, based on its velocity, is determined by the equation: Ek m0(ÃŽ ³ - 1)c2Ek m0c2 / square root of (1 - v2/c2) - m0c2 Theres a lot going on in the above equation, so lets unpack those variables: ÃŽ ³ is the Lorentz factor, which is a scale factor that shows up repeatedly in relativity. It indicates the change in different quantities, such as mass, length, and time, when objects are moving. Since ÃŽ ³ 1 / / square root of (1 - v2/c2), this is what causes the different look of the two equations shown.m0 is the rest mass of the object, obtained when it has a velocity of 0 in a given frame of reference.c is the speed of light in free space.v is the velocity at which the object is moving. The relativistic effects are only noticeably significant for very high values of v, which is why these effects could be ignored for long before Einstein came along. Notice the denominator which contains the variable v (for velocity). As the velocity gets closer and closer to the speed of light (c), that v2/c2 term will get closer and closer to 1 ... which means that the value of the denominator (the square root of 1 - v2/c2) will get closer and closer to 0. As the denominator gets smaller, the energy itself gets larger and larger, approaching infinity. Therefore, when you try to accelerate a particle nearly to the speed of light, it takes more and more energy to do it. Actually accelerating to the speed of light itself would take an infinite amount of energy, which is impossible. By this reasoning, no particle that is moving slower than the speed of light can ever reach the speed of light (or, by extension, go faster than the speed of light). Faster Than the Speed of Light So what about if we did have a particle that moves faster than the speed of light. Is that even possible? Strictly speaking, it is possible. Such particles, called tachyons, have shown up in some theoretical models, but they almost always end up being removed because they represent a fundamental instability in the model. To date, we have no experimental evidence to indicate that tachyons do exist. If a tachyon did exist, it would always move faster than the speed of light. Using the same reasoning as in the case of slower-than-light particles, you can prove that it would take an infinite amount of energy to slow a tachyon down to light speed. The difference is that, in this case, you end up with the v-term being slightly greater than one, which means the number in the square root is a negative. This results in an imaginary number, and its not even conceptually clear what having an imaginary energy would really mean. (No, this is not dark energy.) Faster Than Slow Light As I mentioned earlier, when light goes from a vacuum into another material, it slows down. It is possible that a charged particle, such as an electron, can enter a material with sufficient force to move faster than light within that material. (The speed of light within a given material is called the phase velocity of light in that medium.) In this case, the charged particle emits a form of electromagnetic radiation thats become called Cherenkov radiation. The Confirmed Exception There is one way around the speed of light restriction. This restriction only applies to objects that are moving through spacetime, but its possible for spacetime itself to expand at a rate such that objects within it are separating faster than the speed of light. As an imperfect example, think about two rafts floating down a river at a constant speed. The river forks into two branches, with one raft floating down each of the branches. Though the rafts themselves are each always moving at the same speed, they are moving faster in relation to each other because of the relative flow of the river itself. In this example, the river itself is spacetime. Under the current cosmological model, the distant reaches of the universe is expanding at speeds faster than the speed of light. In the early universe, our universe was expanding at this rate, as well. Still, within any specific region of spacetime, the speed limitations imposed by relativity do hold. One Possible Exception One final point worth mentioning is a hypothetical idea put forth called variable speed of light (VSL) cosmology, which suggests that the speed of light itself has changed over time. This is an extremely controversial theory and theres little direct experimental evidence to support it. Mostly, the theory has been put forward because it has the potential to solve certain problems in the evolution of the early universe without resorting to inflation theory.