What is Inflation: Definition and 413 Discussions

In economics, inflation (or less frequently, price inflation) is a general rise in the price level of an economy over a period of time.
When the general price level rises, each unit of currency buys fewer goods and services; consequently, inflation reflects a reduction in the purchasing power per unit of money – a loss of real value in the medium of exchange and unit of account within the economy. The opposite of inflation is deflation, a sustained decrease in the general price level of goods and services. The common measure of inflation is the inflation rate, the annualised percentage change in a general price index, usually the consumer price index, over time.Economists believe that very high rates of inflation and hyperinflation are harmful, and are caused by excessive growth of the money supply. Views on which factors determine low to moderate rates of inflation are more varied. Low or moderate inflation may be attributed to fluctuations in real demand for goods and services, or changes in available supplies such as during scarcities. However, the consensus view is that a long sustained period of inflation is caused by money supply growing faster than the rate of economic growth.Inflation affects economies in various positive and negative ways. The negative effects of inflation include an increase in the opportunity cost of holding money, uncertainty over future inflation which may discourage investment and savings, and if inflation were rapid enough, shortages of goods as consumers begin hoarding out of concern that prices will increase in the future. Positive effects include reducing unemployment due to nominal wage rigidity, allowing the central bank greater freedom in carrying out monetary policy, encouraging loans and investment instead of money hoarding, and avoiding the inefficiencies associated with deflation.
Today, most economists favour a low and steady rate of inflation. Low (as opposed to zero or negative) inflation reduces the severity of economic recessions by enabling the labor market to adjust more quickly in a downturn, and reduces the risk that a liquidity trap prevents monetary policy from stabilising the economy. The task of keeping the rate of inflation low and stable is usually given to monetary authorities. Generally, these monetary authorities are the central banks that control monetary policy through the setting of interest rates, through open market operations, and through the setting of banking reserve requirements.

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  1. A

    Calculating average inflation rate per year

    Homework Statement An economist has predicted that for the next 5 years, annual inflation will be 8%, and then there will be 5 years at a 6% inflation rate. This is equivalent to what average price change per year for the entire 10-year period? Homework Equations The Attempt at a Solution...
  2. Vigardo

    Inflation of a clamped isotropic and thin circular plastic membrane

    Appreciated experts, I want to model the inflation of a thin and isotropic circular plastic membrane clamped by a ring. I need to determine the maximum deflection at the pole, stresses, strain, etc..., as a function of the applied pressure difference. The large deflection range complicates it...
  3. A

    Does inflation theory have any confirmed predictions?

    Inflation theory, as far as I know, is completely ad-hoc (that is, created to fit already available data). What testable predictions does inflation theory make, and which of these have been confirmed to be accurate?
  4. S

    Next step in inflation theory ?

    Hi Guys, After data release of Planck satellite , at least about early universe cosmology, nothing new except few( i.e Dipole asymmetry of the CMB temperature fluctuations ) in comparison to WMAP results was found. As a case existence of non Gaussianity at the level of squeezed limit has been...
  5. I

    According to the inflation theory

    According to the inflation theory there is a horizon where space is receeding so fast from an observer such that light will never reach the observer. First, I thought that matter could go equal to or faster than light. This being so, if A is receeding at 0.999...c and B is receeding at the same...
  6. S

    Exponential potential for inflation

    hi I want to solve inflation problem for exponential potential. v(\phi) = v_0 exp(-\alpha \phi) (it's known as barrow or pawer law inflation ) we have 2 main equations: H^2 = 8π G / 3 (1/2 (\dot{\phi})^2 + v(\phi)) \ddot{\phi} + 3H \dot{\phi} + v(\phi)'=0 I must solve this 2 equ...
  7. H

    Comparable size of the observable universe immediately after inflation

    Regarding scale. How big was the region of the universe we now understand to be the observable universe, immediately after early inflation? I'm tyring to understand the scale. I know our sphere of observation is very approximately 45 billion light years or something, I don't know for sure...
  8. H

    Early cosmic inflation and the expansion of the universe.

    My question is regarding the early inflationary phase of the Big Bang. As I understand it, inflation is what gave rise to the expansion energy of the universe. Meaning, inflation gave the 'push' so to speak that set the everything moving apart. This makes sense because obviously the universe...
  9. S

    Can Super Inflation Explain the Planck Anomalies?

    I was under the impression that the super inflation generated by the LQC was not enough to give us the 60 minimum e foldings for inflation to solve the horizon problem. However I have just noticed this paper on the arxiv today and I am wondering now if that conclusion is too hasty, any thoughts...
  10. A

    Inflation and Element Formation: Irreconcialble?

    I write this in the hope that somebody reading this can explain to me, a laymen, in non-mathematical, plain English terms, why my thinking is wrong regarding the calculation of the age of the observable Universe and the formation of the elements in the Periodic Table given the (short) age of...
  11. H

    Universe finite or infinite during the first instance of inflation?

    -In the first few fractions of a second after the big bang, was the universe finite and closed during early inflation, before it smoothed out and became flat and infinite? I am wondering because I would like to know if the theory implies that the universe initially inflated with a finite...
  12. wolram

    Exploring Inflation with Rainbow Gravity: A Layman's Guide

    ] arXiv:1310.2072 [pdf, ps, other] Intermediate inflation from rainbow gravity John D. Barrow, Joao Magueijo Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc) It is possible to dualize theories based on deformed dispersion...
  13. jbrussell93

    Grade Inflation: Is a 4.0 GPA from a State School Suspect?

    I've heard people say that a 4.0 GPA can look a bit suspicious to admissions committees for grad school. I'm wondering how true this actually is... I assume it depends greatly on whether the 4.0 is coming from a well known university. Let's say that the 4.0 is just coming from a large state...
  14. andrewkirk

    Can Einstein's Field equation explain inflation?

    I was looking at the wikipedia article about cosmic inflation (you know, the first 10-32 seconds). It says that an inflation hypothesis is a neat way to explain a number of otherwise puzzling observations, but it doesn't say much about what would make inflation occur and it doesn't mention...
  15. D

    What is wrong with eternal inflation model?

    I was thinking that "eternal inflation" model deals nicely with the problem of the beginning of the universe. If I understand this model correctly, Multiverse is a boiling bulk of some sort of very dense vacuum, creating inflationary "bubbles" (baby Universes), finite from the outside but...
  16. Dilatino

    How are inflaton particles that drive the early inflation created?

    Assuming that the early inflation of the universe is driven by the potential energy of some inflaton field(s), the "normal" matter is created only after this rapid inflation has stopped by conversion of the latent energy of the corresponding phase transition to particles. Does this mean that...
  17. A

    Breaking of time diffeomorphisms in inflation

    Hello here, I am currently working on the topic of inflation. It seems that at the stage of inflation, the universe can be described as a de Sitter space. In such a space, all spacetime diffeomorphisms are preserved. (That is something I don't really understand but I keep reading that so I...
  18. A

    Inflation Deflated ? the dead of inlation models ?

    according inflation, the universe should to be uniform in all directions at large scale, but observations from the Planck spacecraft found fluctuations in the cosmic microwave background that undermines the model. http://www.kavlifoundation.org/science-spotlights/kicc-planck-universe
  19. marcus

    Blackforest's question about George Ellis inflation paper

    Blackforest asked about an interesting paper recently posted by G.F.R. Ellis, that MTd2 spotted and added to our bibliography. I hope we can have some discussion of the Ellis paper. Unimodular gravity is a variant of the usual GR which is restricted to metrics which do not feel "vacuum...
  20. marcus

    Where' the hoops? 145 e-fold inflation predicted

    There's a belief floating around that it takes "jumping through a lot of hoops" for a theoretical model to predict inflation AND give an adequate amount AND then stop . The conventional wisdom is it requires fine-tuning for inflation to turn on, go for at least 60 efolds, and then turn off, i.e...
  21. G

    Speed of light during inflation

    It is often said that although the expansion of the universe may create the illusion of objects in very far regions of the universe to recede from each other at superluminal speed, that does not violate c because locally they never move faster than c. This I can understand. How would things...
  22. K

    Early Cosmic Inflation: Questions & Answers

    Hello, In the early stages of Cosmic Inflation, immediately after the Big Bang, all matter was basically energy in a plasma form. It continued to expand for 380,000 years before cooling enough to form the first atoms. I have two questions: 1. Did this matter continue to exist in a...
  23. Mordred

    LambdaCDM inflation model dependancies

    I've been haqving a tough time tracking down which particular inflationary models form the basis of \LambdaCDM. the model I have discounted already is false vacuum A.Guth. some articles seem to suggest concepts from slow roll inflation. Others deal specifically with the inflaton field in...
  24. S

    Did inflation set off the universe?

    Was it inflation that started off the universe to exist, or was it the Big Bang? The reason I ask is because from I've read is that the universe wasn't an explosion, but rather a rapid expansion. Was there a small explosion we call the big bang, then the cosmological inflation? Or was there...
  25. H

    Exploring Inflation: Is the Flat Universe Theory Correct?

    Hi, I've been reading about inflation, and I'm not totally convinced about how it is proposed to result in a flat universe. If I understand it correctly, inflation expanded the universe so rapidly that the actual size of the universe now is 23 orders of magnitude larger than the observable...
  26. marcus

    Bianchi I LQC, Kasner transitions and inflation

    Slides and audio for this talk by Brajesh Gupt were posted online today. LQC bounce creates conditions for inflation. It's important to extend the quantum bounce model to anistropic cases, such as Bianchi I. Anisotropy can affect what one expects from the ensuing inflationary episode. Here...
  27. A

    What slowed or stopped inflation?

    Was it gravity? Does the expansion of the universe have anything to do with the original inflation? One more. What actually is the "fabric" of space that is expanding? You always hear the balloon analogy, so what makes up the rubber of the balloon in real life? Thanks in advance for my...
  28. M

    Exploring Higgs Inflation After Moriond & Planck

    I figure that we need a thread specifically for this topic, while we try to sort out just how minimal physics could be, in the wake of the Moriond conference on the Higgs and the data release from the Planck collaboration. Fedor Bezrukov has written many papers on Higgs inflation, and curiously...
  29. J

    Inflation of singularity at moment of evaporation?

    I have had an idea kicking around in my head for some time now. It all started last summer when I was kayaking down a river and I had stopped in an eddy to relax for a moment. The rate of flow of the water was strong enough to make sizable vortices along the eddy fence around the boulder that...
  30. P

    Inflation, as a tool for supersymmetry breaking

    Hi I know that gravitninos are produced in the Early Universe in reheating (after inflation), is this because the end of inflation/reheating period where the inflaton is oscillating about the minima of the potential is analogous to symmetry breaking?
  31. P

    Inflaton after chaotic inflation

    Can anyone explain to me why after chaotic inflation with V=\frac{1}{2}m^2 \phi^2 that the inflaton behaves as; \phi=\frac{m_p}{m \sqrt{3\pi}t} \sin(mt). because this doesn't satify the slow roll conditions or the eqn of motion for the inflaton. I have read that it asymptotically approaches...
  32. B

    Before Inflation: Elementary Particles Q&A

    Hello all . I have two questions : 1 - Before inflation elementary particles such as matter and photons could not be created and destroyed or could be created and destroyed but could not be permanent ? I mean can we say matter existed before inflation but it was created and destroyed in...
  33. P

    Inflation & Quasars energy and 'fast-forward effect' ?

    Having read the 'The bigger bang' book two times over, I am struck by the fact that the author seems to ask and answer the question of quasar energy emission without stating he is doing so or explaining why it would be wrong to assume he is doing so. In the beginning of the book, Lindsey...
  34. N

    How do inflation, and the zero energy flat universe tie into one another?

    New to cosmology and somewhat confused. I get all the ideas indvidually, that inflation is the exponential growth in the beginning of the universe, than that gravity and matter cancel each other out to make the zero energy universe, and that a flat universe is the only one that is zero energy...
  35. P

    Cosmic Inflation & Fine Structure Constant: Theory & Observations

    I saw this question (in a far removed forum), and I thought it was interesting. Do we have any theoretical reason (or observations) that would suggest that inflation change the fine structure constant.
  36. S

    Inflation as a solution to the Early Universe Enrtopy problem

    I really think this paper http://arxiv.org/abs/1212.1087 which Chronos mentioned in another thread deserves its own thread. Has anyone had a chance to look at it? what do you think? This has been a lot of noise about this issue raised by people like Roger Penrose and Sean Caroll . They have...
  37. thenewmans

    Questions on the Inflation Debate

    The commonly accepted age of the universe is 13.7 billion years. I assume that assumes an inflationary epoch. Since inflation is in debate, what’s the age without it? And since expansion is accelerating, I assume expansion was slower 10 (or 20) billion years ago. Could it be infinitely old? (IE...
  38. N

    No Inflation in Brane Cosmology: Is Dark Energy the Driver?

    In brane cosmology how can there be no such thing as inflation. I was watching a lecture with Neil Turok and he said he made a bet with Hawking that says that the new Planck satellite will give us information that could prove against inflation. So, my question being, instead of inflation in the...
  39. I

    Are Supersymmetric Inflation Models Still Viable After LHC's Latest Results?

    Does anybody know what is the status of supersymmetric inflation model after latest results of LHC concerning SUSY? Have some models been excluded? or do you know some review papers talk about that issue?
  40. R

    Dark Matter and Eternal Inflation

    Before i begin, i will note that i truly don't have any idea of what I'm about to ask, but the questions elude me so ask i must. Firstly, Dark matter: finding it on earth. I've just finished watching a documentary on mapping our universe and within the program was shown a theory of trying to...
  41. S

    How inflation solves the horizon problem

    Hi Guys I've just made a sheet illustrating the horizon problem and how it is solved by inflation. I thought it might be handy for anyone interested in it, or having trouble with it. I'd also appreciate it if some of you could check it over and see if there's anything I have gotten wrong...
  42. F

    Power of inflation in relation to expansion

    how much more power had big bang in inflation theory than in standard expansion theory? (if standard expansion big bang = 1 ) i assume it was over-c because of that power standard expansion would be 18000000 km/min and inflation... ? and after how much time did speed of light...
  43. R

    What is the scientific reasoning behind Inflation after the big bang?

    I understand what inflation is, but what are the reasons behind why scientists are near definitive that it indeed happened? Please go as in depth, complex, or over the top as you need/want.
  44. A

    Inflation and particle horizon

    How can inflation explain the particle horizon's problem?
  45. C

    Inflation model of the universe

    I understand that (from what we can tell) the universe is expanding at an accelerating rate. I'm just curious if it's possible that the universe is expanding in some areas, and receding in others. despite this going against the cosmological principle, is it possible that beyond our bubble of...
  46. R

    Density fluctuations that result after inflation

    This is from Krauss' A Universe from Nothing How could Guth know what density fluctuations arise after inflation? More context to better help a potential answerer:
  47. R

    The phase transition of the universe during inflation

    This is from Krauss' A Universe from Nothing: It seems like he's saying that before inflation kicked in around 10^-36 or 10^-34 I forget which that the universe, I'm guessing from 10^-43 - 10^-36 was in some sort of false vacuum state, analogous to the way matter changes phase from gas to...
  48. T

    Why does inflation lead to a smaller universe at 380000 years?

    Why does inflation mean that the universe was much smaller at 380000 years after the big bang than we would predict from the Big Bang model alone? What would we expect the two sizes to be?
  49. PhysicoRaj

    Time at which price doubles in inflation.

    anybody knows how to calculate the period which a commodity which faces inflation takes to double it's price, without knowing anything except the rate of inflation? You must give a very shortcut method. Thanks.
  50. P

    Big Bang & Inflation: Exploring Infinite Inflation

    "Infinite" inflation Hello all, I have a series of questions relating to the Big Bang and Inflation! First, a disclaimer: I am a science/astronomy/cosmology enthusiast, but I have no advanced education in the subjects. My knowledge is gleaned from as many books as I can read and shows I can...
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