Definition of Closed Timelike Curve

Definition of Closed Timelike Curve A closed timelike curve (sometimes abbreviated CTC) is a theoretical solution to the general field equations of the theory of general relativity. In a closed timelike curve, the worldline of an object through spacetime follows a curious path where it eventually returns to the exact same coordinates in space and time that it was at previously. In other words, a closed timelike curve is the mathematical result of physics equations that allows for time travel. Normally, a closed timelike curve comes out of the equations through something called frame dragging, where a massive object or intense gravitational field moves and literally drags spacetime along with it. Many results that allow for a closed timelike curve involve a  black hole, which allows for a singularity in the normally smooth fabric of spacetime and often results in a  wormhole. One key thing about a closed timelike curve is that it is generally thought the worldline of the object following this curve doesnt change as a result of following the curve. That is to say, the worldline is closed (it loops back on itself and becomes the original timeline), but that has always been the case. Should a closed timelike curve be used to get a time traveler to travel into the past, that most common interpretation of the situation is that the time traveler would have always been part of the past, and therefore thered be no changes to the past as a result of the time traveler suddenly showing up. History of Closed Timelike Curves The first closed timelike curve was predicted in 1937 by Willem Jacob van Stockum and was further elaborated by the mathematician Kurt Godel in 1949. Criticism of Closed Timelike Curves Though the result is technically allowed in some very highly-specialized situations, many physicists believe that time travel is not achievable in practice. One person who supported this viewpoint was Stephen Hawking, who proposed a chronological protection conjecture that the laws of the universe would ultimately be such that they prevent any possibility of time travel. However, since a closed timelike curve doesnt result in changes to how the past unfolded, the various paradoxes that we would normally want to say are impossible dont apply in this situation. The most formal representation of this concept is known as the Novikov self-consistency principle, an idea presented by Igor Dmitriyevich Novikov in the 1980s that suggested that if CTCs are possible, then only self-consistent trips backward in time would be allowed. Closed Timelike Curves in Popular Culture Since closed timelike curves represent the only form of travel backward in time that is allowed under the rules of general relativity, attempts to be scientifically accurate in time travel generally try to use this approach. However, the dramatic tension involved in scientific stories often require some sort possibility, at least, that history could be altered. The number of time travel stories that really stick to the idea of closed timelike curves are pretty limited. One classic example comes from the science fiction short story All You Zombies, by Robert A. Heinlein. This story, which was the basis of the 2014 film Predestination, involves a time traveler who repeatedly goes backward in time and interacts with various previous incarnations, but each time the traveler who comes from later in the timeline, the one who has looped back, has already experienced the encounter (albeit only for the first time). Another good example of closed timelike curves is the time travel plotline that ran through the final seasons of the television series Lost. A group of characters traveled backward in time, in the hopes of altering events, but it turned out that their actions in the past create no change in how events unfolded, but it turns out that they were always part of how those events unfolded in the first place. Also Known As: CTC

Expert Guide How Many Times Should You Take the SAT

Expert Guide How Many Times Should You Take the SAT SAT / ACT Prep Online Guides and Tips How many times can you take the SAT? Is there a limit if you're retaking it to achieveyour ideal score? Why would you want to keep sitting through this high stakestest, anyway? There are several compelling reasons to take the SAT more than once, but you also shouldn't go totally overboard. Let's go overwhen you should retake the SAT, and when it might be time to move on. Reasons to Take the SAT More Than Once Students almost always improve when they retake the SAT.When you take the SAT,you gain valuablereal test experience that helps youfigure out how to manage your time and deal with pressure. Youmight encounter certain problems that stump youand learn the concepts youmissed out on for next time. Because theycan take time to study and improve, lots of students choose to take the SAT more than once to improve the scores they'll ultimately add to their college applications. Some students strategically build up their SAT score section by section. If your college superscores your test resultsor takes the highest scores by section across all the timeyou sat for the test, then you could theoretically focus on Math for one test date, Reading for another date, and Writing and Language for the third. While you shouldn't treat any section as a throwaway section, since a major discrepancy in scores could raise red flags both to your colleges and the College Board, this approach is one way to really hone your knowledge in one area and potentially achieve near-perfect section scores one test date at a time. If you scoreworse than you expected to on the SAT, you might have had a fluke test. There could have been a major passage that just didn't make sense to you, or maybe you were tired, sick, or distracted that day. If this is the case, you should schedule for the next test as soon as possible. So if you're likely to improve your SAT scores every time you take the test, should you just keep taking it over and over again until you hit perfection? Can You Take the SAT an Unlimited Number of Times? How many times can you take the SAT? Technically, you can take the SAT as many times as you want! There are no restrictions for registering for and taking the test. There are 7 test dates throughout the year, so the only limit that stands in your wayis time. Many schools allow you to use Score Choice, or to pick and choose which scores from which test dates you want to send as part of your college application. Not all schools support the use of Score Choice, however, and they take it on good faith that you'll send all your scores. Some notable schools with a "send all scores" policy include Yale, Stanford, Cornell, Carnegie Mellon, and the University of California. So if you can use Score Choice to send only some scores and keep the rest private, and you have the time and money to keep retesting, then technically you could take the SAT as many times as you want. But if your schools don't use Score Choice and you are expected to send all your test scores along with your application, how many times retaking the SAT is too many? How Many SAT Tests Is Too Many? If you're applying to schools that require all scores, like the ones mentioned above, I would recommend not taking the SAT more than six times. If you take the SAT this many or more times, you might be sending the signal that you're not taking the test seriously enough to prep each time or that you have a lot of trouble improving your scores. The SAT is meant to test all students on a level playing field and determine their readiness for college, so it wouldn't look all thatstrong to have to take the testmore than six times to perform well. While real test experience is valuable, you also will gaina lot from focused and purposeful test prep. Perhapsyou keep retaking the SAT and your scores are not improving as much as you'd like. Rather than asking, "How many times can I take the SAT?" you should reconsideryour test prep approach. Are you really uncovering and targeting your weak spots and filling in your knowledge gaps? Are you timing yourself when you take practice tests to practice your pacing? Are you familiar with the best strategies for analyzing the Reading passages or writing the essay? By honing your approach to test prep and really putting in the time and effort to study, you should be able to achieve your target scores within a few administrations of the SAT. Besides what excessive retesting indicates about how you're prepping for the SAT, it also might not be the best idea for a few other reasons. Planning your SAT testing schedule is all about balance. Reasons Not to Overtake the SAT First, it's important to take control of your test prep, diagnose your strengths and weaknesses, and figure out what you need to do to improve your scores. Apart from this, you're probably also taking other tests, like finals or the SAT Subject Tests, along with all your schoolwork, community service, and clubs or sports that require your attention. You wouldn't want to drop the ball at this point in your high school career by diverting attention away from these other pursuits, as these are also all key parts of your college application. Plus, unless you're superhuman or highly skilled at meditating, sitting for the SATtends to involve stress and anxiety.Getting real test experience is helpful in teaching you to regulate your nerves, calm yourself down, and focus, but you also don't need to put yourself through this too many times. Taking the SAT more than six times could potentially become a waste of time, money, and energy. Again, while you can definitely have a fluke testing experience and score much lower than you should, you also don't want to treat any tests as throwaway tests. It's important to take every test seriously so you can get a real sense of your skills and scoring capacity. You can use this same mindsetwith practice tests - by simulating testing conditions and timing yourself, you can build on your testing experience and figure out what you need to learn and practice to boost your scores. Like with everything else you're involved in through school and outside of school, taking the SAT is all about balance. If you set and stick to a study plan and testing schedule, then you'll be able to find the happy medium between testing too often andtesting too little. Belowis one common guide that works for a lot of high school students. SAT Study Plan and Testing Schedule Guide This timeline is effective for a lot of students and gives you time to prep and retake the SAT a few times to hit your target scores. Rather than scouring for test dates to figure out how many times can you take the SAT, you can have everything planned out in advance. 1.Study for the SAT the summer before junior year. You can use online prep, answer SAT Questions of the Day, print official practice tests, try sample questions, and study from books. 2. Register for and take your first real SAT test in the fall of junior year. Depending on how you do, you can later register for the test again. 3. If you're retaking the SAT, you can prep during the winter of junior year and take the SAT again in the spring. You might also be taking SAT Subject Tests at the end of the school year. If you still aren't scoring where you want to score, then you can sign up to take the SAT in the fall of your senior year. 4. Put a lot of effort into test prep the summer between junior and senior year. Figure out what you were missing on the first two administrations of the test, learn the concepts, and apply them through practice problems. You want to do everything you can to prepare, as this test in the fall will likely be your last chance. 5. Take the first available test senior year, before you get too busy with schoolwork and your summer studying is fresh in your mind. This would be in October for the SAT. If you feel this test did not go well, you might be able to retake it one more time, depending on your college deadlines. This is also not an ideal time to take the SAT, as you'll be busy finishing up and sending off the rest of your application. If you're not sure if your scores will be sent to your colleges in time, definitely call or email the admissions office and ask if they'll accept these scores.They might wait for your scoreseven if they arrive after the stated deadline, but you can't bank on this unless they've told you this explicitly. Ambitious students who feel they can achieve a high score even earlier in their high school career might choose to push this schedule forward a year.You could start prepping as a 9th or 10th grader, take the SAT throughout sophomore year, and be all set with yourscores before youeven start the rest of the application process. If you're a strong, academically achieving student, you might already have the math, reading, and writing skills you need to score highly on the SAT before you even reach junior year. Just like with your test prep, it's important to reflect on what works best for you. As everyone has different preferences, strengths, and weaknesses, there's no one size fits all approach to studying for and taking the SAT. This testing schedule works for a lot of students, but ultimately it's up to you to decide on and stick to the schedule that will allow you to perform your best. To Sum Up: How Many Times Should You Take the SAT? Around four times of sitting for the SAT (sometimes more, sometimes less) should likely be enough for you to reach your target scores, along with many more practice tests and effective test prep on your own. Don't underestimate the power of prep in helping you master the SAT. In the end though, you shouldn't be afraid to take real tests, as they are valuable training experiences and you can almost always improve your scores or make up for an off day. Give yourself enough test dates so you don't run out of opportunities to take the test, and find the balance between retesting, studying, and accomplishing your goals in time for your college deadlines. What's Next? What's a good SAT score for 10th grade? 9th grade? What about overall for your college applications? These articles explore this topic of when to take the SAT even further, revealing what your early test scores indicate about your future performance. Are you aiming for a perfect 1600? This full scorer shares his strategies for scoring an 800on both Math and Reading and Writing. While most schools place a great deal of importance on the SAT or ACT, there are actually some schools now that have test optional or test flexible policies. Before you design your plan, make sure you understand the requirements of your colleges. Want to improve your SAT score by 160 points? Check out our best-in-class online SAT prep classes. We guarantee your money back if you don't improve your SAT score by 160 points or more. Our classes are entirely online, and they're taught by SAT experts. If you liked this article, you'll love our classes. Along with expert-led classes, you'll get personalized homework with thousands of practice problems organized by individual skills so you learn most effectively. We'll also give you a step-by-step, custom program to follow so you'll never be confused about what to study next. Try it risk-free today:

MCH Programs and Policies Assignment Example | Topics and Well Written Essays - 250 words

MCH Programs and Policies - Assignment Example y contraceptives were safe for use and a litigation by over 60 women and medical groups’ in 2001 forced FDA to approve emergency contraceptives for use over-the-counter for all women. Thereafter, various state government established laws that allowed sale of emergency contraceptives without a doctor’s prescription but in 2011, the Obama administration restricted access to those under 17 years (Center for Reproductive Rights, 2015). The policy has improved economic welfare of many women. They are not inconvenienced by unwanted pregnancies, although it has not reduced the risk of acquiring sexual infections. Religious groups believe plan B causes abortion while but researchers prove it prevents implantation. Emergency contraceptives have reduced agony and suffering from women who previously had to seek abortion services after unprotected sex. College girls no longer drop out of school due to unwanted pregnancy inconveniences (Glasier & Baird, 1998). Drug manufacturers, women rights group, FDA and religious groups have vested interests the bill. Drug manufactures, would want it approved for use by all without restrictions. Women groups find it a right violation and medical groups such as pediatric associations believe that it important because it reduces the cost of unwanted pregnancies and the risk of complications during delivery and late abortions. Religious groups find it immoral. The FDA and government find that people are likely to abuse the drugs (Culp-Ressler, 2013; Faà ºndes, Tavara, Brache, & Alvarez, 2007). Culp-Ressler, T. (2013). Judge Rules Emergency Contraception Should Be Available To All Women Over The Counter. Retrieved from http://thinkprogress.org/health/2013/04/05/1826411/judge-plan-b-over-counter/ Faà ºndes, A., Tavara, L., Brache, V., & Alvarez, F. (2007). Emergency contraception under attack in Latin America: response of the medical establishment and civil society. Reproductive Health Matters, 15(29),