Here I will explain the difference between matter, anti matter, dark matter, and negative matter in a concise and understandable way. I have seen confusion pop up in various online forums and comments on the recent announced trapping of an anti atom by CERN. The first thing to know is that for a physicist there are four fundamental forces of nature which are always at work . These are the familiar Gravity and Electromagnetism, as well as the generally unfamiliar strong and weak atomic forces. The atomic forces work on the length scale of atoms, Electromagnetism and gravity work on the length scale of the universe though in fundamentally different ways. The different kinds of matter interact through these forces in different ways. Normal matter like that which we are all made of interacts via all four forces in the ways which we are familiar with. All of the science and technology we have done to this point is based on normal matter and how it behaves. But for a few experiments and in certain particle accelerators all we have done has been with normal matter. Hence it's name. Anti matter is just like normal matter only the sign of certain properties is different. The classic case would be the electron, which has as it's anti particle the anti-electron also known as the positron. Electrons are negatively charged, and Positrons are positively charged. Yet they are identical in every other way. Then their are particles like neutrons and protons which are made of even smaller particles called quarks. Quarks interact via the strong atomic force, and electromagnetism. Anti Quarks have opposite charges to Quarks in those two forces. Dark matter on the other hand only interacts by way of gravity and the weak atomic force. Dark matter does not interact via either the strong atomic force or electromagnetism hence dark matter cannot be seen and is hard to detect. It only interacts via the weak force which is what keeps neutrons and protons inside the nucleus of atoms together. Such is why experiments to detect dark matter directly rely on a particle of dark matter bumping into a particle of matter dead bang on the nucleus of an atom of normal matter. Most of the reason we think dark matter exists has to do with the fact that it solves problems in cosmology in a very expedient way without us having to alter General Relativity. It is widely agreed that dark matter whatever it turns out to be quantifies how much we really don't know about the matter in the universe. Negative matter is a hypothetical type of matter which if it exist will have negative mass and negative energy. It will in essence have a negative gravitational charge and repel normal matter. Yet it will interact just like any other matter in every other way. This table summarizes the differences in how each type of matter would interact with the different forces. Normal Matter Anti- Dark- Negative- Gravity As usual As usual* Opposite sign Electromagnetism No charge *We assume that antimatter behaves as normal matter under gravity. The truth is we have never seen a large enough mass of it to know for certain it behaves the same. When it comes to Negative matter we know nothing and it may not even exist outside of certain theories. Dark matter is on the edge of being a confirmed real entity.

We have already met gravitational fields, where the gravitational field strength of a planet multiplied by an objects mass gives us the weight of that object, and that the gravitational field strength, of Earth is equal to the acceleration of free fall at its surface. We will now consider gravitational fields that are not uniform and how to calculate the value of for any given mass. Gravity as a field of force [edit] The effects of the Earth's gravity extend far out into space. For example, the Moon is kept in orbit by the Earth even though it is 400, 000km away (where gravity is the centripetal force). The Earth has a gravitational field that will attract any object with mass towards the centre of the planet. Radial Fields [edit] The Earths radial gravitational field is represented by the lines. The Earth has a radial field of gravity, which means that the gravitational field is circular and acts from the centre point. You can see on the diagram that near the Earth's surface the lines are closer together than higher up. The closeness of the lines represent the relative strength of the field, so from the diagram, you can tell that the strength of the field decreases with altitude. Further apart lines represent points where the field is weaker. The arrows show the direction in which the force on an object will act, which is towards the centre of the Earth. Uniform fields [edit] Gravity field lines representation is arbitrary as illustrated here represented in 30x30 grid to 0x0 grid and almost being parallel and pointing straight down to the center of the EarthThe Earth's gravitational field is represented by parallel lines on small scales. A uniform field , however, has the lines perfectly parallel. The Earth's gravitational field can be considered to be uniform on the scale of small things such as cars, balls, and planes. For small heights at this scale (a few dozen kilometres), the strength of the field doesn't change enough to be noticeable. Again, the arrows point towards the centre of the Earth, since that is the way objects fall. Newton's ideas of gravity [edit] Isaac Newton was trying to find a way to explain why objects fell towards the centre of the Earth instead of simply staying put. He began to link the falling of an apple, with the "falling" of the Moon towards the Earth, and came up with his law of gravitation . He suggested that any two objects with a mass would have a force of attraction between them. This force of attraction would be proportional to their masses, so that larger masses would have a stronger force of attraction than a smaller mass. The gravitational field of every object is a radial field, since the mass is concentrated at the objects centre, and as you already know, this is the point at which gravity could be said to act. As you can see, a quarter of lines of force goes through the plane when the distance is doubled. The strength of a radial field decreases as you move further away from it. As you can see on the diagram on the right, the number of field lines going through the plane quarter when the distance is doubled, and it will be of the original value if the distance was tripled. This is called the inverse square law, and is true for anything which is a point source, such a light from a point or the amount of radiation emitted. The inverse square law follows . Using the above, Newton suggested that the force of attraction was proportional to the two masses as well as the distance between them: . This relationship is the basis of how Newton's law of gravitation is often stated: Any two point masses attract each other with a force that is proportional to each of their masses and inversely proportional to the square of the distance between them. However, to make this into an equation, we need to add in a constant of proportionality, G: . Where G is the gravitational constant . There is also a minus sign in the equation, which will be explained in the "electric fields" module, where we will encounter repelling as well as attracting forces. is also sometimes written as , so that capital M represents a large mass such a planet, and lower case m represents a small mass such as a ball or an aeroplane. Defining the gravitational field strength [edit] The gravitational field strength tells us how strong a gravitational field is. You may recall that the gravitational field strength of the Earth near its surface is . This means an object that is near the surface of the earth will accelerate towards it at . We could then define the gravitational field strength as the acceleration an object will experience within that gravitational field. A better definition, however, can be derived from the equation. Making the subject of this gives us , or . From this arrangement of the equation, our definition of gravitational field strength now becomes: The gravitational field strength at a point is the force per unit mass exerted on a mass placed at that point. This means that the gravitational field strength, is equal to the force experienced by a mass of 1kg in that gravitational field. From the new definition, it follows that gravitational field strength is measured in , though it is perfectly acceptable to use for situations where it is treated as an acceleration (such as the acceleration of an object in free fall). Finding the field strength of a mass [edit] Since and , they can be combined to give: (by substituting F for mg) (by cancelling the lower case 'm's) You can use this to find the gravitational field strength of a mass at a particular point, r. Note that the gravitational field strength of the Earth near its surface is numerically equal to the acceleration of free fall.

University of California Hastings College of the Law 2016 Abstract: In the American system of dual sovereignty, states have primary authority over matters of state law. In nonpreemptive areas in which state and federal regimes are parallel — such as matters of court procedure, certain statutory law, and even some constitutional law — states have full authority to legislate and interpret state law in ways that diverge from analogous federal law. But, in large measure, they don’t. It is as if federal law exerts a gravitational force that draws states to mimic federal law even when federal law does not require state conformity. This paper is the first to explore the widespread phenomenon of federal law’s gravitational pull. The paper begins by identifying the existence of a gravitational force throughout a range of procedural and substantive law felt by a host of state actors, including state rulemakers, legislators, judges, and even people themselves. It then excavates some explanatory vectors to help understand and appreciate why federal law exerts a gravitational force. Finally, the paper considers some normative concerns with state acquiescence to the federal gravitational pull. Number of Pages in PDF File: 52 Keywords: gravity, gravitational, federalism, following, federal rules, bowers, marriage, title vii,

You probably have an idea of what gravity is, but did you know that you, right now, are actually pulling on every other object in the universe? Find out more about the gravitational force and learn an equation to calculate its pull on other objects. Click "next lesson" whenever you finish a lesson and quiz. Got It You now have full access to our lessons and courses. Watch the lesson now or keep exploring. Got It You're 25% of the way through this course! Keep going at this rate, and you'll be done before you know it. Way to go! If you watch at least 30 minutes of lessons each day you'll master your goals before you know it. Go to Next Lesson Take Quiz Congratulations on earning a badge for watching 10 videos but you've only scratched the surface. Keep it up! Go to Next Lesson Take Quiz You've just earned a badge for watching 50 different lessons. Keep it up, you're making great progress! Go to Next Lesson Take Quiz You have earned a badge for watching 20 minutes of lessons. You have earned a badge for watching 50 minutes of lessons. You have earned a badge for watching 100 minutes of lessons. You have earned a badge for watching 250 minutes of lessons. You have earned a badge for watching 500 minutes of lessons.

The only thing one needs to do is observe the interaction of particles, such as gravitational attraction.All mass exerts and experiences gravity and, in space, the gravitational attraction even between masses of modest size can significantly affect their motion.Within a given region, the change in mass due to rising or falling water reserves influences the strength of the local gravitational attraction.Connoisseurs of watchmaking know that the tourbillon, in a vertical position, uses the rotation of the cage in a given time to shield the balance from the influence of the gravitational attraction of the Earth...

Universe May Have Been Around Since Forever, According to Rainbow

Physicists have used the quantum nature of matter to obtain a highly precise value for the universal gravitational constant, the 'big G' that appears in Isaac Newton's law of how gravity pulls together everything, from planets to apples. Although the technique still needs refinements, physicists believe that in the future it will beat the precision of conventional methods — and hopefully solve apparent discrepancies between measurements that have long puzzled physicists. In a study described today in Nature , researchers measured the minuscule gravitational tug between rubidium atoms and a 516-kilogram array of tungsten cylinders...

The galaxy cluster Abell 1689 is famous for the way it bends light in a phenomenon called gravitational lensing. Study of the cluster has revealed secrets about how dark energy shapes the universe. Credit: NASA, ESA, E. Jullo (JPL/LAM), P. Natarajan (Yale) and J-P. Kneib (LAM) A mysterious quantity known as dark energy makes up nearly three-fourths of the universe, yet scientists are unsure not only what it is but how it operates. How, then, can they know this strange source exists? The expanding universe In 1929, American astronomer Edwin Hubble studied exploding stars known as supernovae to determine that the universe is expanding. Since then, scientists have sought to determine just how fast. It seemed obvious that gravity, the force which draws everything together, would put the brakes on the spreading cosmos, so the question many asked was, just how much was the expansion slowing? These galaxy clusters are representative of more than 80 clusters that were used to track the effects of dark energy on these massive objects over time. Most of the matter in galaxy clusters is in the form of very hot gas, which emits copious amounts of X-rays. Credit: NASA/CXC/SAO/A.Vikhlinin et al. In the 1990s, two independent teams of astrophysicists again turned their eyes to distant supernovae to calculate the deceleration. To their surprise, they found that the expansion of the universe wasn't slowing down, it was speeding up! Something must be counteracting gravity, something which the scientists dubbed "dark energy." Calculating the energy needed to overcome gravity, scientists determined that dark energy makes up roughly 68 percent of the universe. Dark matter makes up another 27 percent, leaving the "normal" matter that we are familiar with to make up less than 5 percent of the cosmos around us. Quintessence Knowing how dark energy affects the spreading universe only tells scientists so much. The properties of the unknown quantity are still up for grabs. Recent observations have indicated that dark energy has behaved constantly over the universe's history, which provides some insight into the unseen material. One possible solution for dark energy is that the universe is filled with a changing energy field, known as "quintessence." Another is that scientists do not correctly understand how gravity works. The leading theory, however, considers dark energy a property of space. Albert Einstein was the first to understand that space was not simply empty. He also understood that more space could continue to come into existence. In his theory of general relativity, Einstein included a cosmological constant to account for the stationary universe scientists thought existed. After Hubble announced the expanding universe, Einstein called his constant his "biggest blunder." But Einstein's blunder may be the best fit for dark energy. Predicting that empty space can have its own energy, the constant indicates that as more space emerges, more energy would be added to the universe, increasing its expansion. Although the cosmological constant matches up with observations, scientists still aren't certain just why it fits. Dark energy versus dark matter Like dark energy, dark matter continues to confound scientists. While dark energy is a force that accounts for the expanding universe, dark matter explains how groups of objects function together. In the 1950s, scientists studying other galaxies expected gravity to cause the centers to rotate faster than the outer edges, based on the distribution of the objects inside of them. To their surprise, both regions rotated at the same rate, indicating that the spiral galaxies contained significantly more mass than they appeared to. Studies of gas inside elliptical galaxies and of clusters of galaxies revealed that this hidden matter was spread throughout the universe. Scientists have a number of potential candidates for dark matter, ranging to incredibly dim objects to strange particles. But whatever the source of both dark matter and dark energy, it is clear that the universe is affected by things that scientists can't conventionally observe.

Does the moon have significantly different gravity depending on

This article needs attention from an expert in International law . Please add a reason or a talk parameter to this template to explain the issue with the article. WikiProject International law (or its Portal) may be able to help recruit an expert. International legal theory comprises a variety of theoretical and methodological approaches used to explain and analyse the content, formation and effectiveness of public international law and institutions and to suggest improvements. Some approaches center on the question of compliance: why states follow international norms in the absence of a coercive power that ensures compliance. Other approaches focus on the problem of the formation of international rules: why states voluntarily adopt international legal norms, that limit their freedom of action, in the absence of a world legislature. Other perspectives are policy oriented; they elaborate theoretical frameworks and instruments to criticize the existing rules and make suggestions on how to improve them. Some of these approaches are based on domestic legal theory, others are interdisciplinary, while others have been developed expressly to analyse international law. Natural law [edit] Many early international legal theorists were concerned with axiomatic truths thought to be reposed in natural law. 16th century natural law writer, Francisco de Vitoria, a professor of theology at the University of Salamanca, examined the questions of the just war, the Spanish authority in the Americas, and the rights of the Native American peoples. Eclectic or Grotian approach [edit] Hugo Grotius, a Dutch theologian, humanist and jurist played a key role in the development of modern international law. In his ("Three Books on the Law of War and Peace") of 1625, and drawing from the Bible and from the St. Augustine's just war theory, he argued that nations as well as persons ought to be governed by universal principle based on morality and divine justice. Drawing, though, from domestic contract law, he argued that relations among polities ought to be governed by the law of peoples, the, established by the consent of the community of nations on the basis of the principle of, that is, on the basis of the observance of commitments. On his part, Christian von Wolff, contended the international community should be a world superstate (civitas maxima), having authority over the component member states. Emmerich de Vattel rejected this view and argued instead for the equality of states as articulated by 18th century natural law. In Le droit des gens, Vattel suggested that the law of nations was composed of custom and law on the one hand, and natural law on the other. During the 17th century, the basic tenets of the Grotian or eclectic school, especially the doctrines of legal equality, territorial sovereignty, and independence of states, became the fundamental principles of the European political and legal system and were enshrined in the 1648 Peace of Westphalia. Legal positivism [edit] The early positivist school emphasized the importance of custom and treaties as sources of international law. Early positivist scholar Alberico Gentili used historical examples to posit that positive law (jus voluntarium) was determined by general consent. Another positivist scholar, Richard Zouche, published the first manual of international law in 1650. Legal positivism became the dominant legal theory of 18th century and found its way into international legal philosophy. At the time, Cornelius van Bynkershoek asserted that the bases of international law were customs and treaties commonly consented to by various states. John Jacob Moser emphasized the importance of state practice in international law. Georg Friedrich von Martens, published the first systematic manual on positive international law, Precis du droit des gens moderne de l'Europe. During the 19th century, positivist legal theory became even more dominant due to nationalism and the Hegelian philosophy. International Commercial law became a branch of domestic law: private international law, separate from public international law. Positivism narrowed the range of international practice that might qualify as law, favouring rationality over morality and ethics. The 1815 Congress of Vienna marked the formal recognition of the political and international legal system based on the conditions of Europe.