What is Cosmic inflation: Definition and 37 Discussions

In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10−36 seconds after the conjectured Big Bang singularity to some time between 10−33 and 10−32 seconds after the singularity. Following the inflationary period, the universe continued to expand, but at a slower rate. The acceleration of this expansion due to dark energy began after the universe was already over 7.7 billion years old (5.4 billion years ago).Inflation theory was developed in the late 1970s and early 80s, with notable contributions by several theoretical physicists, including Alexei Starobinsky at Landau Institute for Theoretical Physics, Alan Guth at Cornell University, and Andrei Linde at Lebedev Physical Institute. Alexei Starobinsky, Alan Guth, and Andrei Linde won the 2014 Kavli Prize "for pioneering the theory of cosmic inflation." It was developed further in the early 1980s. It explains the origin of the large-scale structure of the cosmos. Quantum fluctuations in the microscopic inflationary region, magnified to cosmic size, become the seeds for the growth of structure in the Universe (see galaxy formation and evolution and structure formation). Many physicists also believe that inflation explains why the universe appears to be the same in all directions (isotropic), why the cosmic microwave background radiation is distributed evenly, why the universe is flat, and why no magnetic monopoles have been observed.
The detailed particle physics mechanism responsible for inflation is unknown. The basic inflationary paradigm is accepted by most physicists, as a number of inflation model predictions have been confirmed by observation; however, a substantial minority of scientists dissent from this position. The hypothetical field thought to be responsible for inflation is called the inflaton.In 2002 three of the original architects of the theory were recognized for their major contributions; physicists Alan Guth of M.I.T., Andrei Linde of Stanford, and Paul Steinhardt of Princeton shared the prestigious Dirac Prize "for development of the concept of inflation in cosmology". In 2012 Guth and Linde were awarded the Breakthrough Prize in Fundamental Physics for their invention and development of inflationary cosmology.

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  1. Aromalsp

    I Developing Inflation Theory w/o Dark Energy: Alan Guth 1980

    The term "dark energy" was first coined by physicist Michael Turner in 1998. Alan Guth and his team proposed the inflation theory in 1980. The Einstein–Hamilton–Jacobi equation was used by researchers to calculate the rate of cosmic inflation by taking into account the effects of dark energy...
  2. S

    I No symmetries in the Universe at the Big Bang...?

    I apologize in advance if this is a stupid question but... According to some scenarios about the beginning of the universe (namely cosmological inflation), in layman's terms, everything was born out of a quantum fluctuation which caused a violent expansion. In this case, since an expanding...
  3. S

    I Particle production in an expanding universe?

    I was reading this interesting article [1] which talks about particle production in an expanding universe. Usually this process is proposed to have occurred in the early universe, when the expansion was in the inflationary phase and it was so powerful that matter was created in particle...
  4. SH2372 General Relativity - Lecture 10

    SH2372 General Relativity - Lecture 10

    0:00 Cosmological redshift 18:08 Solving the Friedmann equations 34:34 Accelerated expansion and the cosmological constant 56:10 Cosmological inflation
  5. PainterGuy

    I Some questions about Cosmic Inflation

    Hi, I have some questions about the cosmic inflation. As I tried to find the answers, I got little more confused. I have mentioned all the quotes from relevant articles which I found confusing. I understand that there are quite a few questions but they are all related to each other and I...
  6. L

    B Cosmic Inflation & Censorship: Validation or Corrections?

    Is it just waiting for empirical validation or are there still any corrections to do?
  7. 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...
  8. 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...
  9. 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?
  10. RogerWaters

    B Does dark energy or cosmic inflation explain flatness?

    As I understand, the main theoretical virtue of Guth's inflation hypothesis is that it explains a bunch of otherwise hard-to-account-for phenomena under the standard big bang model without inflation: the Horizon Problem, the Flatness problem, the Monopole problem, and also the problem of how...
  11. 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'...
  12. S

    A Can Cosmic Inflation and String Theory change fundamental laws?

    Is there any version of string theory or cosmological inflation that allows the most fundamental laws and constants change between universes? String Theory and Cosmological Inflation are two theories or models that allow multiple universes to exist. Laws and constants of physics could change...
  13. S

    A Calculating the Gravitational wave spectrum with Inflation as a source

    I am interested in knowing how to calculate the gravitational wave (GW) spectrum with inflation as a source, I have some background in inflation but I am not so familiar about calculating the GW spectrum. I am reading a paper (https://arxiv.org/abs/0804.3249) about it, however, a big part of it...
  14. 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...
  15. Sophrosyne

    B The Hubble deep field photos and the edge of the universe

    The Hubble telescope was able to capture images of the edges of our visible universe in its deep space photos. These were among its most breathtaking pictures. They show galaxies from about 14 billion light years away, as well as in the past, from the very beginning of time and space in our...
  16. BadgerBadger92

    B What Causes the Phenomenon of Cosmic Inflation?

    Not long after the Big Bang, space expanded faster than light for a brief amount of time, slowed down, then sped up again. Is there an answer to this question?
  17. R

    I Did cosmic inflation happen everywhere in the Universe?

    General Relativity equations tells us that the earliest time of the universe which our physics can tell us had infinite space and infinite density (i.e. matter). Then space started expanding, thus increasing the distance of any 2 points of that infinite dense matter, thus making it less dense...
  18. W

    I VSl as an alternative to cosmic inflation

    It has been proposed that a varying speed of light can resolve certain cosmological problems thought to be solved by cosmic inflation. An example is this paper here by Albrecht and Magueijo: https://arxiv.org/pdf/astro-ph/9811018.pdf and this paper by Moffat https://arxiv.org/abs/gr-qc/9211020 I...
  19. Arman777

    B The Universe without Cosmic Inflation?

    I don't know this question makes sense or not but; Respect to the two possible size universe models (finite and infinite) how would be the evolution of the universe without the cosmic inflation?
  20. S

    B Angular momentum, degeneracy pressure, and cosmic inflation

    Considering the angular momentum of a collapsing star preventing it from resulting in a black hole by degeneracy pressure, are there ekpyrotic universe models that include angular momentum and degeneracy pressure as key factors of cosmic inflation?
  21. W

    Mathematica Cosmic inflation using mathematica

    In cosmic inflation, we have the equation of motion for the inflaton given by, $$\ddot\phi + 3H(1 + Q)\dot\phi + V_\phi = 0$$ the Friedman equation is given by $$H^2 = \frac{1}{3 M_p^2}(\frac{1}{2} \dot\phi^2 + V + \rho_r)$$ where ##M_p## is the reduced Planck mass. The differential equation...
  22. Urs Schreiber

    A Starobinsky Inflation and Supergravity

    The available experimental data prefers plateau models of cosmic inflation, and among them Starobinsky inflation (aka R^2 inflation) is preferred, even if maybe not significantly. Since Starobinsky inflation is pure gravity (the inflaton field here is an effective incarnation of a higher...
  23. S

    B Matter-antimatter annihilation and inflation

    Is there any link between the energy released from the annihilation of matter-antimatter during baryogenesis and cosmic inflation or expansion/dark energy? This question came up when reading: https://www.nasa.gov/mission_pages/chandra/news/08-160.html
  24. DiracPool

    Inflation and Monopoles: Exploring the Mysteries of Cosmic Expansion

    1. Inflation--I've been doing a little study into cosmic inflation, and a question that many people (including myself) seem to have a hard time wrapping their head around is why was there a need for inflation rather than just assuming that the universe just started off flat, homogeneous, and...
  25. H

    Detecting the presence of other universes

    In the inflationary Big Bang model, our universe is one of the many pocket universes in the multiverse. How can we detect the existence of the other pocket universes? I presumed that all the pocket universes exist in the same physical space. So in principle, they can exert influence on one...
  26. T

    Covariance betw scalar amplitude & spectral index in Planck?

    I am reading some of "Planck 2013 results. XXII. Constraints on inflation." The paper is full of values for various inflationary parameters under various models, with their confidence intervals. For instance, in Table 5 on page 13, the authors report that — for a model including both running of...
  27. Kiyal

    Why are the more distant galaxies/stars moving faster away?

    The universe is expanding: Why is it that the further galaxies and stars are away from us they appear to be moving away at a much faster speed than ones closer to home?
  28. Kiyal

    Can someone explain what it is meant by a 'Flat Universe'?

    I have been reading and looking at videos regarding cosmic inflation and it said that the universe is flat. I am no expert and have no mathematical background - I love reading about space and learning new things about it. It just really irritates me when things go right over my head and this...
  29. N

    Does Cosmic inflation cause spacetime to move?

    I've thought about this a lot and have tried to find the answer but have been unsuccessful. In the event of the big bang did it inflate through spacetime without effecting it other than warping by mass or did it actually cause the spacetime to flow or move outwards with the inflation?
  30. S

    Cosmic inflation and singularity

    "Cosmic inflation" and singularity Hi. I saw this on Wikipedia: http://en.wikipedia.org/wiki/Chronology_of_the_universe#Planck_epoch Later: If there was no "traditional Big Bang" with inflationary cosmology, would this remove the singularity at the beginning of the universe? If so...
  31. 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...
  32. 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...
  33. 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.
  34. R

    Cosmic inflation and gravitational waves.

    After the big bang, did the cosmic inflation of space occur as a gravitational wave?
  35. S

    What gave rise to cosmic inflation of the early Universe?

    What gave rise to cosmic inflation of the early Universe?
  36. X

    Can Cosmic Inflation Explain the Accelerating Universe?

    If the hot Big-Bang model is accurate (and seems like it is), could cosmic inflation (maybe a further extension) explain why the universe is accelerating or will we have to retreat to extra-dimensions (superstring theory and leaking gravity)? There are other problems with this theory of...