Inflation Definition and 415 Threads

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. B

    I How we are in a matter dominated universe (without antimatter annihilation)

    Assuming the situation where there is an infinite inflation stream, from which bubble universes are appearing in locally slowed regions. There could be many many such bubble universes and so very rare occurrences in some bubbles can sometimes happen. Also assumed, as is often postulated, that...
  2. Mordred

    A Is the Jeffry Scale/Bayes Factor Still Used for Testing Inflationary Models?

    I know Encyclopaedia Inflationaris (ASPIC library) used the Jeffry scale/ Bayes factor to test various inflationary models but I'm also aware there was contention in that methodology. Does anyone know if the methodology is still being used or has it been replaced with a different methodology ?
  3. M

    A Higgs inflation and quadratic gravity

    After the news of Peter Higgs's death, I was thinking of the Higgs field and boson, how central they are to physics now, and the remaining mysteries associated with them. One such is the meaning of the mass actually observed for the Higgs boson. In the mainstream of theoretical physics, the...
  4. Samama Fahim

    I Cosmological Scalar Field Density Dilution

    This is from Modern Cosmology, Scott Dodelson, Chapter 6. For the part "Show that its energy density dilutes as ##a^{−3}##", following is my attempt: In the equation ##\frac{\partial \rho}{\partial t} = -3H(P+\rho)##, put ##P = \frac{1}{2} \dot{\phi}^2-V(\phi)## and ##\rho=\frac{1}{2}...
  5. W

    B Cosmic Graviton Background and Primordial Gravitational Waves

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  6. chasrob

    What is the Theoretical Energy Density of Inflation?

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  7. AHSAN MUJTABA

    A Scalar Field Dynamics in Inflation

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  8. KingoftheChaosEmpire

    "Rigid airship" using low density hydrogen (LDH) inflation

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  9. Cody Livengood

    B What if we cut out the Big Bang and inflation?

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  10. svenz706

    A Non-minimally coupled inflation — expansion

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  11. AHSAN MUJTABA

    I What is the significance of slow-roll inflation in cosmology?

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  12. PainterGuy

    I Some questions about Cosmic Inflation

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  13. L

    B Cosmic Inflation & Censorship: Validation or Corrections?

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  14. P

    B Explaining Cosmic Inflation using analogies

    An analogy to understand Cosmic Inflation: If the universe grew in size from a subatomic size to the size of a tennis ball (or softball) in a tiny fraction of a second, then a football inflated at the same rate will grow to an approximate size of our solar system. Is this a correct analogy...
  15. S

    I Varying laws of high energy physics in inflation?

    I am have some questions that have arisen while reading an old but interesting article by Andreas Albrecht [1] that cites an article by Andrei Linde in the 90s on cosmic inflation [2]...Albrecht's paper is related to his ideas on "clock ambiguity" in which he proposes that the laws of physics...
  16. K

    I Higgs inflation and primordial black holes

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  17. Alpha2021

    A Graceful exit of a cosmological inflation model

    How to determine whether a cosmological inflation model (say single-field slow-roll inflation) gracefully exit or not? Is it like showing that inflation is ending at some value of inflaton?
  18. RogerWaters

    B Does dark energy or cosmic inflation explain flatness?

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  19. RogerWaters

    B Why doesn't cosmic inflation violate conservation of energy?

    Hi all, I'm not a physics student (although I have a PhD in a different field) and so don't have the math, but I'm trying to interpret a key passage from Krauss' book 'A Universe from Nothing' where he is (trying?) to explain, in 'layman's terms', what Alan Guth termed 'the ultimate free lunch'...
  20. B

    I Why aren't Gravitational waves factored in to inflation formulas?

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  21. Ranku

    I Inflation and size of the Universe

    Among other things, inflation explains the horizon problem, as to why even though the proper distance between two antipodal points on the last scattering surface is greater than the horizon distance, and therefore causally disconnected, yet the two points have the same temperature. So is this...
  22. elcaro

    I How long did inflation last in an eternal inflating universe?

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  23. kyphysics

    How is Inflation Affecting Your Daily Expenses?

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  24. AHSAN MUJTABA

    I Slow-roll Inflation and Horizon Problem

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  25. T

    Inflation rate and discount rate?

    I have a payback for a project of 6 years without counting the inflation rate and discount rate. If the Payback is 6 years, how do you add an average yearly inflation rate of 2.10% and a discount rate of 5.75%?
  26. J

    I Exploring Rivals for Inflation in Cosmology: Characteristics and Implications

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  27. S

    I Wheeler's Pre-geometry model and multiple universes?

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  28. S

    I Is there any inflationary model without a fundamental theory?

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  29. Buzz Bloom

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  30. T

    I Is the Universe bigger than we think?

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  31. W

    B Nearly Scale Invariant Power Spectrum in inflation

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  32. I

    I Big Bang singularity: can we say anything about its size?

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  33. N

    Inflation and measurement of cosmic bodies

    Hi, Is it true that measurement proves the universe has inflated by 13.8 billion light years, and if so, how do we estimate the age or distance of those measurements? What's giving me pause is my assumption that the oldest light measured (furthest away) is 13.8 billion light years old, but...
  34. S

    A Can Cosmic Inflation and String Theory change fundamental laws?

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  35. S

    A Calculating the Gravitational wave spectrum with Inflation as a source

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  36. C

    I Tom Banks' New Paper - Contra Eternal Inflation

    https://arxiv.org/abs/1910.12817 As a layman I've come to share this paper, mainly to garner the opinions of others to see what you all think, it was fairly insightful and seems interesting at least.
  37. O

    I What does the cosmic inflation theory actually say about flatness?

    I just read an article by Natalie Wolchover (a smart and knowledgeable writer as far as I can tell) in Quanta about the new analysis supporting a closed universe. In the article she makes this comment, "The leading theory of the universe’s birth, known as cosmic inflation, yields pristine...
  38. Quantum Alchemy

    B How constrained are the initial conditions of the universe?

    Do we know? Do we have any idea? There seems to be 2 schools of thought. 1. The initial conditions can be almost any value with universes inflating with different laws of physics. This is the multiverse and string theory 10^500 false vacua view. 2. The initial conditions are more restrained...
  39. QuarkDecay

    I Solving the Horizon Problem: 1 Source or 105?

    It says that since there is homogeneity in the Universe's temperature, all these points must have come from one source (or a source close to each other?) at a certain time. Then it also calculates the number of these sources and it's ~105. But isn't that very dense mass right before the Big...
  40. W

    I Does Spatial Curvature Falsify Eternal Inflation?

    I have often heard it said that the picture of a multiverse inspired from eternal inflation is not falsifiable. However this paper from 2012 claims that it is: https://arxiv.org/pdf/1202.5037.pdf specifically it says, as I understand it, that if one were to measure sufficient positive spatial...
  41. W

    B Can Hypothetical FTL Technologies Enable Travel to Other Bubble Universes?

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  42. M

    A Observables when the symmetry is not broken?

    Hi, Let be a scalar field φ that permeates all space. The quantum of the field has a mass m. The field is at the minimum of its potential. When this minimum is for φ≠0 (a broken symmetry), the quantum may be observed by exciting the field, as with the Higgs boson. But if the symmetry is not...
  43. Ken Lehn

    B Is Dark Energy Born at the Big Bang or Continually Created?

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  44. QuarkDecay

    Where Did I Go Wrong Solving the Inflation Model Integral?

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  45. newrd

    B Andromeda Collision VS Expansion

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  46. Arman777

    B How exactly inflation solves the Horizon Problem

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  47. A

    I Inflation resolves the horizon problem

    Can anyone please explain how inflation removes the horizon. problem of standard cosmology . As much I know inflation is a period of accelerated expansion which can be approximated by ~exp(βt) which can be achieved if the energy density remains constt. throughout (e.g ≠ε(t)),which is the case...
  48. FallenApple

    Is There a Safe Way to Beat Inflation?

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  49. Ranku

    I Inflation and the size of the Universe

    By how many times is the size of the observable universe larger than expected because of inflation?
  50. Green dwarf

    I Is inflation needed to explain uniformity?

    Inflation seems to explain why distantly separated parts of the universe are at the same temperature etc. But I've never seen any reason why the different parts should have been at different temperatures in the first place. Is there a simple answer to that?
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