Physics (from the Ancient Greek φύσις physis meaning "nature") is the fundamental branch of science that developed out of the study of nature and philosophy known, until around the end of the 19th century, as "natural philosophy". Today, physics is ultimately defined as the study of matter, energy and the relationships between them.[citation needed] Physics is, in some senses, the oldest and most basic pure science; its discoveries find applications throughout the natural sciences, since matter and energy are the basic constituents of the natural world. The other sciences are generally more limited in their scope and may be considered branches that have split off from physics to become sciences in their own right. Physics today may be divided loosely into classical physics and modern physics.
Ancient references to the dilemma are found in the writings of classical philosophers. Their writings indicate that the proposed problem was perplexing to them and was commonly discussed by others of their time as well.
Aristotle (384–322 BC) was puzzled by the idea that there could be a first bird or egg and concluded that both the bird and egg must have always existed:
If there has been a first man he must have been born without father or mother – which is repugnant to nature. For there could not have been a first egg to give a beginning to birds, or there should have been a first bird which gave a beginning to eggs; for a bird comes from an egg.[2]
The same he held good for all species, believing, with Plato, "that everything before it appeared on earth had first its being in spirit."[3]
Plutarch (46–126) referred to a hen rather than simply a bird. Plutarch discussed a series of arguments based on questions posed in a symposium. Under the section entitled "Whether the hen or the egg came first", the discussion is introduced in such a way suggesting that the origin of the dilemma was even older:
...the problem about the egg and the hen, which of them came first, was dragged into our talk, a difficult problem which gives investigators much trouble. And Sulla my comrade said that with a small problem, as with a tool, we were rocking loose a great and heavy one, that of the creation of the world..."[4][5][6]
Macrobius (early 5th century), a Roman philosopher, found the problem to be interesting:
You jest about what you suppose to be a triviality, in asking whether the hen came first from an egg or the egg from a hen, but the point should be regarded as one of importance, one worthy of discussion, and careful discussion at that."[7][8]
In System of Nature by Baron D'Holbach (1770, translated into English in 1797), he asks "was the animal anterior to the egg, or did the egg precede the animal?" (part 1, chapter 6).
Stephen Hawking and Christopher Langan have argued that the egg came before the chicken,[9] though the real importance of the question has faded since Darwin's On the Origin of Species and the accompanying Theory of Evolution, assuming the question intended "egg" to mean an egg in general rather than an egg that hatches into a chicken. According to Popular Science, the egg came first as it evolved prior to birds.[10] However, it is also reasonable to suppose that the egg being referred to is a chicken egg. In that case, it has been argued, from the perspective of the Philosophy of Science,[11] that the answer is unknowable. This result (by the pseudonymous author Joseph Bonilla) appears to be correct although it has not yet been published in a peer review journal. (Christopher Langan has also argued that it was the egg that came first under this interpretation, but that interpretation was merely published on his own site, and cannot be considered a peer reviewed publication.) The paper by the pseudonymous author Joseph Bonilla supersedes the article by Christopher Langan and the comments by Stephen Hawking; thus, it represents an evolution of philosophical thought on this subject, and is the last word on this subject as of today.
In physics, a force is any interaction which tends to change the motion of an object.[1] In other words, a force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described by intuitive concepts such as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newtons and represented by the symbol F.
The original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. If the mass of the object is constant, this law implies that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object. As a formula, this is expressed as:
\vec{F} = m \vec{a} where the arrows imply a vector quantity possessing both magnitude and direction.
Related concepts to force include: thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque which produces changes in rotational speed of an object. In an extended body, each part usually applies forces on the adjacent parts; the distribution of such forces through the body is the so-called mechanical stress. Pressure is a simple type of stress. Stress usually causes deformation of solid materials, or flow in fluids.
Dolphins with calves produce milk in their mammary glands; dolphins can simultaneously lactate and gestate, so a pregnant dolphin may continue feeding an already-born calf.
Dolphin calves typically stay with their mothers for up to five years, and they may nurse for more than a year during that time.
The average lactation for dolphin calves has not been calculated to date, due to the challenges of studying lactation in non-captive dolphins, although average nursing periods tend to last between 6 months and 2 years.
According to Kristi West and her colleagues at the Sarasota Dolphin Research Program, which collected and analyzed bottlenose dolphin milk samples between 1998 and 2006, calves need high-fat milk.
The proportion of fat available in mother’s milk was directly related to the mass of the calves.
Researchers also found that as fat content decreased and milk water and potassium content rose, calf mass proportionally decreased.
The availability of high-fat prey for the mother is critical to the quality of her milk supply and to the rapid growth and development of her calves.
In their seminal 1940 paper, “The Composition of Dolphin Milk”, Lillian Eichelberger and her colleagues at the University of Chicago found that “it had a fishy odor when freshly drawn and the taste was oily and lacked sweetness.”
(172) Though Eichelberger noted some variation between species, all the samples collected by her team were high in protein and fat, and low in lactose.
Sharks, like many other animals, migrate for purposes of mating and giving birth. These migrations are timed by seasons of the year, which cause water temperature changes that may trigger sharks to migrate to their breeding and pupping grounds. The sandbar shark is one specie that migrates to breeding grounds to reproduce.
The sandbar shark, for example, is found in large numbers off the east coast of Florida, in spring. This is a major mating ground for the shark. Sandbar sharks migrate north in early summer, and females move into northeastern bays and estuaries in June to have their pups. Delaware Bay is a major pupping ground for sandbar sharks. Throughout the summer months, from June to early September, the pups will remain in the relative safety of these bays and estuaries and will then migrate south as winter approaches. Adult sandbar sharks will continue their migration northward after pupping season and will move south for the winter as water temperatures begin to cool.
Another primary cause of animal migrations is availability of food sources. Movements of fish which sharks prey on will cause the sharks to follow in pursuit. Often, the movements of food fish are related to water temperature changes similar to those that factor in shark migrations. Seasonal availability of marine mammals also factors in migration patterns of those species of sharks that feed upon them. For example, great white sharks reach the northernmost parts of their range in summer. Along the eastern Pacific ocean, this area extends up to the southern Alaskan islands. In early spring, the sharks have returned to the coast of California. In April, they arrive at the Farallon Islands and Ano Nuevo Island off the coast of the San Francisco Bay to feed on seals. In mid to late April the sharks migrate to the Channel Islands off the coast of Los Angeles, to have their pups, and in May, the sharks return to Ano Nuevo and the Farallons to feed on elephant seal pups that were born in the early spring. Elephant seal pups are very high in fat and are an excellent food source for great white sharks.
If you are entering into the world of snails, you will also begin to notice that the way in which they are built has allowed for their survival through centuries. One of the ways in which this has continued to build is through the abilities to reproduce by these creatures. The different features in which they can do this also provide them with the capacity to keep slugging on the land. Reproduction of Snails Snails will be able to reproduce differently than almost any other type of creature. This begins with the build that all snails have. Snails are considered to be hermaphrodites. This means that every snail will have both male and female reproductive organs. Most terrestrial gastropods are hermaphrodites. The only snails that have not adapted this attribute are some freshwater and marine species, specifically including Apple Snails and periwinkles. These two types of snails still have separate male and female individuals. The land snails will be considered sexually mature from one month and a half to 5 years, depending on species. This is because the life span of most land species does not last for more than five to seven years, allowing for a faster growth rate of the species. The make-up of the snails will include their reproductive organs on the bottom of their body. This is close to the front of their body as well, allowing for easier abilities to mate. The mating practices of snails allow them to deliver eggs for new snails to be brought into life at a consistent rate. Snails will go through a complete mating ritual with each other, usually which will communicate to the other snail for an average of two to twelve hours. At the end of this ritual, the pair will fertilize the eggs in the other, so both of them will deliver eggs. It is known that a snail can carry up to 100 eggs at a time. When the eggs are fertilized, they will go through a process of growth inside the snail, until they are ready to be delivered. After that, both snails lay their eggs and bury them into separate places inside a small hole made in the topsoil in a cool place. This will allow the eggs to develop without being harmed. It will typically take a snail egg two to four weeks in order to develop. (1) As soon as they hatch, they will immediately move into a survival mode. This is because their shells will still be in a weak form. Their reaction is to find calcium as soon as they hatch by either eating their own egg or eating other eggs in order to get the extra nutrients. It will take around three months for the snails to completely form and look like a miniature version of an adult snail of their species. While this takes place, they will stay in a nest that has been built for them, with the transformations being seen through a change in color, from a clear color into a blue then into the adult form that is representative of the species. After the snails are completely developed, they will detach from their parents. The mating procedure of snails is one that moves through a specific process that helps the species to grow and survive. This process start from the beginning of sexual maturity, followed by finding the right mate, locating and creating a place to deliver the eggs, hatching of the eggs and ending with the develop of small snails.
Physics (from the Ancient Greek φύσις physis meaning "nature") is the fundamental branch of science that developed out of the study of nature and philosophy known, until around the end of the 19th century, as "natural philosophy". Today, physics is ultimately defined as the study of matter, energy and the relationships between them.[citation needed] Physics is, in some senses, the oldest and most basic pure science; its discoveries find applications throughout the natural sciences, since matter and energy are the basic constituents of the natural world. The other sciences are generally more limited in their scope and may be considered branches that have split off from physics to become sciences in their own right. Physics today may be divided loosely into classical physics and modern physics.
ReplyDeleteAncient references to the dilemma are found in the writings of classical philosophers. Their writings indicate that the proposed problem was perplexing to them and was commonly discussed by others of their time as well.
ReplyDeleteAristotle (384–322 BC) was puzzled by the idea that there could be a first bird or egg and concluded that both the bird and egg must have always existed:
If there has been a first man he must have been born without father or mother – which is repugnant to nature. For there could not have been a first egg to give a beginning to birds, or there should have been a first bird which gave a beginning to eggs; for a bird comes from an egg.[2]
The same he held good for all species, believing, with Plato, "that everything before it appeared on earth had first its being in spirit."[3]
Plutarch (46–126) referred to a hen rather than simply a bird. Plutarch discussed a series of arguments based on questions posed in a symposium. Under the section entitled "Whether the hen or the egg came first", the discussion is introduced in such a way suggesting that the origin of the dilemma was even older:
...the problem about the egg and the hen, which of them came first, was dragged into our talk, a difficult problem which gives investigators much trouble. And Sulla my comrade said that with a small problem, as with a tool, we were rocking loose a great and heavy one, that of the creation of the world..."[4][5][6]
Macrobius (early 5th century), a Roman philosopher, found the problem to be interesting:
You jest about what you suppose to be a triviality, in asking whether the hen came first from an egg or the egg from a hen, but the point should be regarded as one of importance, one worthy of discussion, and careful discussion at that."[7][8]
In System of Nature by Baron D'Holbach (1770, translated into English in 1797), he asks "was the animal anterior to the egg, or did the egg precede the animal?" (part 1, chapter 6).
Stephen Hawking and Christopher Langan have argued that the egg came before the chicken,[9] though the real importance of the question has faded since Darwin's On the Origin of Species and the accompanying Theory of Evolution, assuming the question intended "egg" to mean an egg in general rather than an egg that hatches into a chicken. According to Popular Science, the egg came first as it evolved prior to birds.[10] However, it is also reasonable to suppose that the egg being referred to is a chicken egg. In that case, it has been argued, from the perspective of the Philosophy of Science,[11] that the answer is unknowable. This result (by the pseudonymous author Joseph Bonilla) appears to be correct although it has not yet been published in a peer review journal. (Christopher Langan has also argued that it was the egg that came first under this interpretation, but that interpretation was merely published on his own site, and cannot be considered a peer reviewed publication.) The paper by the pseudonymous author Joseph Bonilla supersedes the article by Christopher Langan and the comments by Stephen Hawking; thus, it represents an evolution of philosophical thought on this subject, and is the last word on this subject as of today.
In physics, a force is any interaction which tends to change the motion of an object.[1] In other words, a force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described by intuitive concepts such as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newtons and represented by the symbol F.
ReplyDeleteThe original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. If the mass of the object is constant, this law implies that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object. As a formula, this is expressed as:
\vec{F} = m \vec{a}
where the arrows imply a vector quantity possessing both magnitude and direction.
Related concepts to force include: thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque which produces changes in rotational speed of an object. In an extended body, each part usually applies forces on the adjacent parts; the distribution of such forces through the body is the so-called mechanical stress. Pressure is a simple type of stress. Stress usually causes deformation of solid materials, or flow in fluids.
Dolphins with calves produce milk in their mammary glands; dolphins can simultaneously lactate and gestate, so a pregnant dolphin may continue feeding an already-born calf.
ReplyDeleteDolphin calves typically stay with their mothers for up to five years, and they may nurse for more than a year during that time.
The average lactation for dolphin calves has not been calculated to date, due to the challenges of studying lactation in non-captive dolphins, although average nursing periods tend to last between 6 months and 2 years.
According to Kristi West and her colleagues at the Sarasota Dolphin Research Program, which collected and analyzed bottlenose dolphin milk samples between 1998 and 2006, calves need high-fat milk.
The proportion of fat available in mother’s milk was directly related to the mass of the calves.
Researchers also found that as fat content decreased and milk water and potassium content rose, calf mass proportionally decreased.
The availability of high-fat prey for the mother is critical to the quality of her milk supply and to the rapid growth and development of her calves.
In their seminal 1940 paper, “The Composition of Dolphin Milk”, Lillian Eichelberger and her colleagues at the University of Chicago found that “it had a fishy odor when freshly drawn and the taste was oily and lacked sweetness.”
(172) Though Eichelberger noted some variation between species, all the samples collected by her team were high in protein and fat, and low in lactose.
Sharks, like many other animals, migrate for purposes of mating and giving birth. These migrations are timed by seasons of the year, which cause water temperature changes that may trigger sharks to migrate to their breeding and pupping grounds. The sandbar shark is one specie that migrates to breeding grounds to reproduce.
ReplyDeleteThe sandbar shark, for example, is found in large numbers off the east coast of Florida, in spring. This is a major mating ground for the shark. Sandbar sharks migrate north in early summer, and females move into northeastern bays and estuaries in June to have their pups. Delaware Bay is a major pupping ground for sandbar sharks. Throughout the summer months, from June to early September, the pups will remain in the relative safety of these bays and estuaries and will then migrate south as winter approaches. Adult sandbar sharks will continue their migration northward after pupping season and will move south for the winter as water temperatures begin to cool.
Another primary cause of animal migrations is availability of food sources. Movements of fish which sharks prey on will cause the sharks to follow in pursuit. Often, the movements of food fish are related to water temperature changes similar to those that factor in shark migrations. Seasonal availability of marine mammals also factors in migration patterns of those species of sharks that feed upon them. For example, great white sharks reach the northernmost parts of their range in summer. Along the eastern Pacific ocean, this area extends up to the southern Alaskan islands. In early spring, the sharks have returned to the coast of California. In April, they arrive at the Farallon Islands and Ano Nuevo Island off the coast of the San Francisco Bay to feed on seals. In mid to late April the sharks migrate to the Channel Islands off the coast of Los Angeles, to have their pups, and in May, the sharks return to Ano Nuevo and the Farallons to feed on elephant seal pups that were born in the early spring. Elephant seal pups are very high in fat and are an excellent food source for great white sharks.
ReplyDeleteIf you are entering into the world of snails, you will also begin to notice that the way in which they are built has allowed for their survival through centuries. One of the ways in which this has continued to build is through the abilities to reproduce by these creatures. The different features in which they can do this also provide them with the capacity to keep slugging on the land.
ReplyDeleteReproduction of Snails
Snails will be able to reproduce differently than almost any other type of creature. This begins with the build that all snails have. Snails are considered to be hermaphrodites. This means that every snail will have both male and female reproductive organs. Most terrestrial gastropods are hermaphrodites. The only snails that have not adapted this attribute are some freshwater and marine species, specifically including Apple Snails and periwinkles. These two types of snails still have separate male and female individuals.
The land snails will be considered sexually mature from one month and a half to 5 years, depending on species. This is because the life span of most land species does not last for more than five to seven years, allowing for a faster growth rate of the species. The make-up of the snails will include their reproductive organs on the bottom of their body. This is close to the front of their body as well, allowing for easier abilities to mate.
The mating practices of snails allow them to deliver eggs for new snails to be brought into life at a consistent rate. Snails will go through a complete mating ritual with each other, usually which will communicate to the other snail for an average of two to twelve hours. At the end of this ritual, the pair will fertilize the eggs in the other, so both of them will deliver eggs. It is known that a snail can carry up to 100 eggs at a time.
When the eggs are fertilized, they will go through a process of growth inside the snail, until they are ready to be delivered. After that, both snails lay their eggs and bury them into separate places inside a small hole made in the topsoil in a cool place. This will allow the eggs to develop without being harmed.
It will typically take a snail egg two to four weeks in order to develop. (1) As soon as they hatch, they will immediately move into a survival mode. This is because their shells will still be in a weak form. Their reaction is to find calcium as soon as they hatch by either eating their own egg or eating other eggs in order to get the extra nutrients. It will take around three months for the snails to completely form and look like a miniature version of an adult snail of their species. While this takes place, they will stay in a nest that has been built for them, with the transformations being seen through a change in color, from a clear color into a blue then into the adult form that is representative of the species. After the snails are completely developed, they will detach from their parents.
The mating procedure of snails is one that moves through a specific process that helps the species to grow and survive. This process start from the beginning of sexual maturity, followed by finding the right mate, locating and creating a place to deliver the eggs, hatching of the eggs and ending with the develop of small snails.