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. Z

    An interesting notion about inflation.

    I was thinking about how big the universe got after inflation occured. Then I thought about Hubble's parameter. Ho = V / d (At the big bang, the distance between the two edges of the universe were zero) Ho = V / 0 Ho = ∞ km*mpc / s Therefore, the rate of the expansion must have been...
  2. bcrowell

    Inflation requires initial symmetry?

    I'm reading Roger Penrose's Cycles of Time. On p. 124 he's explaining why he thinks inflation doesn't solve the mystery of why the universe started out in a low-entropy state. He argues that a high-entropy collapsing FLRW universe would consist of "a horrendous mess of congealing black holes,"...
  3. E

    Inflation Theory: Matter-Antimatter Annihilation Concept

    How is the inflation theory supported by/related to the matter-antimatter annihilation concept of quantum mechanics?
  4. S

    Inflation and initial conditions

    Its been argued that inflation needs the initial conditions to be finely tuned: eg: http://en.wikipedia.org/wiki/Inflation_(cosmology)#Fine-tuning_problem does this paper resolve this problem...
  5. H

    Examining Grade Inflation in High School: My Daughter's Experience

    My daughter is a senior in High School (local public, not private) and just found out her GPA (4.0 unadjusted, ~4.4 adjusted for AP classes) ranks her 44 out of 450 seniors in her school. While I'm delighted she is in the top 10% of the class, I think it's absurd that 43 seniors have better...
  6. N

    Universe inflation faster than c

    The current theory regarding the beginning of the universe insists that there was a brief period of inflation where the growth of the universe out paced the speed of light growing to light years in diameter in a few minutes. How is it possible?
  7. J

    Inflation is not an Aggregate Quantity

    Economists try to reduce inflation to a single quantity in order to plot changes in such things as real income and real GDP. However, the changes in buying habits do not change equally for people of all income levels. 85% of productivity increases of the 35% increase in productivity we have...
  8. K

    Eternal Inflation Time Will End

    Eternal Inflation "Time Will End" This paper came out last week and looks very interesting but of course relies on M-Theory: http://arxiv.org/abs/1009.4698
  9. marcus

    Hartle Hawking offer probabilities for observations (eternal inflation picture)

    Hartle Hawking suggest probabilities for observations (eternal inflation picture) http://arxiv.org/abs/1009.2525 Eternal inflation without metaphysics James Hartle, S.W. Hawking, Thomas Hertog 4 pages (Submitted on 13 Sep 2010) "In the usual account of eternal inflation the universe is...
  10. K

    Doppler Effect Proven by Red Light from Distant Galaxies

    claim: the red light observed from distant galaxies proves they are moving away. (doppler effect right?) null: because light becomes red diffracting through a medium like space dust or even by gravitation. sorry if I'm off base or 50years behind, just a general "yes/no" or "get out of my forum...
  11. MTd2

    How to avoid singularities in AS Gravity? Find non perturbative inflation

    http://arxiv.org/abs/1008.2768 "To pursue our analysis further, we must determine more carefully the relationship between the renormalization scale µ and the density ρ. One appealing choice, advocated by Weinberg in his analysis of inflation in asymptotically safe gravity [3], is to take the...
  12. R

    Given LQC would a massive black hole undergo inflation?

    I just read the thread on inflation is very unlikely. Then I read the paper by Abhay Ashtekar, David Sloan Loop quantum cosmology and slow roll inflation Although, I did not comprehend all of the implications what seemed to be implied was Given enough mass at some critical density...
  13. T

    Universe expanded faster than the speed of light during inflation

    How is it possible that the universe expanded faster than the speed of light during inflation when this is the "cosmic speed limit"?
  14. E

    Inflation is very unlikely less than 10^-6.6×10^7

    Do you agree with physicist Sean Carroll that inflation is very unlikely? http://blogs.discovermagazine.com/cosmicvariance/2010/07/08/how-finely-tuned-is-the-universe/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+CosmicVarianceBlog+%28Cosmic+Variance%29
  15. D

    How much did the universe grow during inflation?

    Was reading that shortly after the BB, the universe blow up by a factor of 10 to the 50 in 10-33 seconds. What does 10 to the 50 mean in terms of distance & size? All i know is its a large number.
  16. R

    Was Gravity turned off during inflation?

    Do the current models of inflation contain an implicit understanding that gravity is some how turned off during the inflationary expansion? Does the scientific community believe that gravity is a temperature dependent phenomina?
  17. P

    Why do we need inflation to explain the homogeneity of CMB?

    Can't we simply assume that the initial condition for the universe is perfectly spherically symmetric, and the problem is solved? In other words, can't we make the CMB homogeneous just by imposing homogeneous initial conditions? The fluctuations can be explained by quantum effects. Of course...
  18. P

    Inflation or normal space/time misunderstood?

    Please forgive my ignorance but: I am trying very hard to understand how expanding space works. The problems I have are: 1. If expanding space has enough "connection" (friction?) to pull galaxies apart then it should also have a resistance to planets in orbit, rockets continuing on their...
  19. S

    Are Inflation and the Multiverse Indisputably Linked?

    It seems many forms of inflation, such as eternal inflation and chaotic inflation imply a multiverse, but do they all?
  20. G

    Did inflation itself make the universe bigger than what we currently observe

    Noob alert. Totally naive question. Reading V.J. Stenger's "God: The Failed Hypothesis". He says that the observable size of the universe, 10^26 meters, is only 10^61 times bigger than the Planck distance, and he says inflation caused the universe to expand by a factor of 10(10^100) from...
  21. H

    Gravity and Time Dilation: Length Contraction and Mass Inflation?

    According to SR theory, relative motion leads to -length contraction -mass inflation -time dilation. In GR theory, gravity leads to time dilation. Does it also lead to -length contraction? -mass inflation?
  22. E

    String theory cosmology on inflation, CMB, gravitional waves?

    cosmology strings vs loops How well does string cosmology account for inflation, CMB, gravitational waves, evolution classically using FRW metric? does string cosmology offer either qualitative or quantitative predictions? This paper addresses these in the loop framework...
  23. C

    Inflation and Assuming the 'just so'

    In essence, is it the case that there is no advancement in understanding that we still must assume that like in the classical big bang theory that conditions were 'just so' at the 'start'? I don't have a problem with inflation but essentially the same problem remains. Conditions are assumed...
  24. M

    How can space be created faster than light during inflation?

    I have a question that bothers me. well, i have a lot of question that bother me. But for now, i will share only one. When inflation began after the big bang, the amount of space that was created exceeded the speed of light. How was that possible?
  25. A

    What changes the rate of inflation

    I was wondering, if inflation caused space to expand so rapidly, what happened to slow it down to the current rate?
  26. edpell

    News What is the real rate of inflation?

    What is the "real" rate of inflation? What is the "real" rate of inflation? The U.S. Federal Government used one formula to calculate before the Clinton administration and now uses a different formula. The two give answers that often differ by a factor of two. Which, if either, is the right...
  27. M

    Is the temperature of the universe affected by inflation?

    hi everyone, i am not a physicist, so please forgive me and help me to clarify some basic concepts. in the context of the inflation of the universe, as i understand it, it was the energy density of the void that expanded space-time, so that the energy density remaining (almost) constant coupled...
  28. C

    Inflation Theory: Could There Be Other Bubble Universes?

    does the inflation theory say that there could be infanet other bubble iniverses or that our bubble universe is expanding as the galexys move outwards?
  29. S

    Does the Big Bang Model Support Instantaneous Inflation in an Infinite Universe?

    The Big Bang model describes a smoothly expanding universe from a point where the current laws of physics break down. However if the universe is infinite, it would be infinite down to this point and presumably before it. This would imply instantaneous inflation from 0 to infinity. The universe...
  30. edpell

    Inflation - can someone please explain it?

    What is inflation (in big bang theory not economics)?
  31. D

    Horizon problem - why do we need inflation?

    Why do we need an inflation to solve the horizon problem? http://en.wikipedia.org/wiki/Horizon_problem If O(t) is omnuim ((c) Frederik) - wavefunction of the whole Universe then initial conditions like O(t=0) = const solve the problem?
  32. A

    Find out how much the universe grew by during the period of inflation

    Is it possible to find out how much the universe grew by during the period of inflation after the big bang?
  33. marcus

    Steven Weinberg offers a way to explain inflation

    Mtd2 spotted this paper by Steven Weinberg that just went on arxiv. http://arxiv.org/abs/0911.3165 Asymptotically Safe Inflation Steven Weinberg 13 pages (Submitted on 16 Nov 2009) "Inflation is studied in the context of asymptotically safe theories of gravitation. It is found to be possible...
  34. P

    Inflation theory; dead or alive?

    Not so long ago, any article, book or treatise regarding the history of the universe seemed to take the "inflation" theory as more or less established fact, whilst also admitting that the finer details were not quite figured out. Is this spectacular theory still regarded as being part of our...
  35. M

    Recommend some papers or books on Inflation

    Could someone recommend some papers or books on Inflation? I know nothing about it, so I need some accessible ones. Thx.
  36. E

    What is the more puzzling our universe with inflation or without it?

    Hi all, I know that inflation solves shortcomings of Standard big bang cosmology, but doesn't intoducing inflation puts us in another puzzle , what is the mechanism which is responsible for inflation? I mean what is the more puzzling our universe with inflation or without it?
  37. C

    Q: About the relations bitween the inflation and matter's properties

    My question goes like this: Did the inflation following the Bing Bang caused matter to emerge as it is in our universe? In other words, was it the inflation itself that gave matter - electrons, neutrons and protons - its properties (physical size, quantums, velocity, mass), or perhaps the two...
  38. T

    How does inflation fit into the position of the Earth?

    You can get a calculator and start counting the errors and false assumptions contained below if you want.. but I got to ask.. If the furthest we can see is 14 billion light-years away (because it's been 14 billion years since the big bang and that's all the time light has had to travel such a...
  39. E

    Chaotic Eternal Inflation vs. False Vacuum Eternal Inflation

    I hope someone can help me understand some inflation principles. In Alan Guth's popular book: The Inflationary Universe, he presents a schematic of a false vacuum universe decaying into pocket universes. The false vacuum expands exponentially as the pocket universes are continuously...
  40. A

    Solving Nicaragua's 1988 Inflation Problem

    Homework Statement During 1988 Nicaragua's inflation rate averaged 1.3% perd day. This means that on average, prices went up by 1.3 percent from one day to the next. By what percentage did Nicaraguan prices increase in June of 1988? What was Nicaragua's annual inflation rate during 1988...
  41. J

    Inflation and GUTs: Energy Scales & Model Dependence

    Can someone please clarify if the energy scales of Inflation & GUTs are identical, or model-dependent ? One typically sees ~10^15 Gev to 2x10^16 Gev in the literature, which is a small variance, but its not clear if there are `standard values'. I am also curious if one can have inflation...
  42. K

    What exactly is cosmological inflation?

    What exactly is cosmological inflation? Just a hypothesis that the rate of expansion is increasing? What is negative-pressure vacuum energy density? If the universe is expanding faster than the speed of light, how do any photons reach us from anywhere other than our sun? Thanks in advance!
  43. E

    Chaotic Inflation Models & Equations

    When using the Friedmann equation (flat space, no cosmological constant): H = sqrt (8 pi G / 3 ) * rho, if we use rho in mass/volume, H is in (time)^-1 like it should. Now for some inflation models, we use: H = sqrt (8 pi G / 3 ) * V(Phi). It seems that V(Phi) should also be able to be...
  44. M

    Exploring the Hypothetical Inflation of the Universe

    Hypothetically, was there ever a time during inflation of the universe when the density of the universe would have been equal to that of water, and we could have swam through it? If so, how big would the universe have been at that moment?
  45. Xezlec

    Inflation: Why all the 10^27s everywhere?

    I was reading about inflation on Wikipedia (warning: I don't really understand physics and cosmology) and I noticed that it said that inflation and dark energy were kind of broadly similar but that their energy scales were off by a factor of about 10^27. This weirded me out a little because I...
  46. Z

    Scale of inflation and dark energy

    I keep reading that the energy scale of inflation is possibly 1024eV, while the energy scale of dark energy is around 10-3eV. What exactly are these scales referring to? Is it the energy required to accelerate the universe at the corresponding rates of acceleration? What...
  47. H

    Finite universe and inflation theory

    Hi, I haven't found special topic about cosmology on this site so I hope this cathegory fits the best. The questions are: 1) Is cosmos(universe) finite or infinite? According to some articles I have read about inflation it seems that inflation theory works only with finite number of particles...
  48. T

    Explanation on how inflation solves the horizon and flatness problem

    Hi, I'm totally lost on how inflation solves the horizon and flatness problem. Flatness Problem Explanation I have d/dt(1/Ha)<0 and therefore |\Omega-1| is driven towards zero rather than away from it. My Confusion Doesn't inflation increase the volume of the universe...
  49. rootX

    Unpredictable inflation and borrowing money

    Is it true that we should borrow money during high inflation periods and lend during deflation periods?
  50. F

    Is there a beginning to chaotic inflation?

    Is chaotic inflation eternal into the past forever, as well as into the future forever. In the theory was there a beginning to it, or has it always been?
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