Big bang theory Definition and 93 Threads

The Big Bang theory is the prevailing cosmological model explaining the existence of the observable universe from the earliest known periods through its subsequent large-scale evolution. The model describes how the universe expanded from an initial state of high density and temperature, and offers a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background (CMB) radiation, and large-scale structure.
Crucially, the theory is compatible with Hubble–Lemaître law — the observation that the farther away galaxies are, the faster they are moving away from Earth. Extrapolating this cosmic expansion backwards in time using the known laws of physics, the theory describes an increasingly concentrated cosmos preceded by a singularity in which space and time lose meaning (typically named "the Big Bang singularity"). Detailed measurements of the expansion rate of the universe place the Big Bang singularity at around 13.8 billion years ago, which is thus considered the age of the universe.After its initial expansion, an event that is by itself often called "the Big Bang", the universe cooled sufficiently to allow the formation of subatomic particles, and later atoms. Giant clouds of these primordial elements – mostly hydrogen, with some helium and lithium – later coalesced through gravity, forming early stars and galaxies, the descendants of which are visible today. Besides these primordial building materials, astronomers observe the gravitational effects of an unknown dark matter surrounding galaxies. Most of the gravitational potential in the universe seems to be in this form, and the Big Bang theory and various observations indicate that this excess gravitational potential is not created by baryonic matter, such as normal atoms. Measurements of the redshifts of supernovae indicate that the expansion of the universe is accelerating, an observation attributed to dark energy's existence.Georges Lemaître first noted in 1927 that an expanding universe could be traced back in time to an originating single point, which he called the "primeval atom". Edwin Hubble confirmed through analysis of galactic redshifts in 1929 that galaxies are indeed drifting apart; this is important observational evidence for an expanding universe. For several decades, the scientific community was divided between supporters of the Big Bang and the rival steady-state model which both offered explanations for the observed expansion, but the steady-state model stipulated an eternal universe in contrast to the Big Bang's finite age. In 1964, the CMB was discovered, which convinced many cosmologists that the steady-state theory was falsified, since, unlike the steady-state theory, the hot Big Bang predicted a uniform background radiation throughout the universe caused by the high temperatures and densities in the distant past. A wide range of empirical evidence strongly favors the Big Bang, which is now essentially universally accepted.

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  1. J

    Questioning the Big Bang Theory

    I am having problem with understanding the concept of big bang theory. Actually I don't believe in the theory. How can we say that this universe was formed because of a big explosion? We can't answer the question what happened before that.
  2. C

    What caused the tiny variations in the Cosmic Microwave Background?

    In my opinion if the Big Bang Theory is correct, it would have resulted in a really massive black hole, "Ultramassive Black Hole(UBH)". Great Attractor could be the location of the "UBH", origin of the Big Bang. This could explain the Dark flow and all galaxies should orbit around the "UBH"...
  3. M

    Why Do We Believe the Big Bang Contained All Matter and Energy in the Universe?

    Why do we think that the Big Bang contained "all" the matter/energy in the universe? If we imagine the point, the "big bang point" to be some accumulation of mass, what makes us think that it should have "waited" for all the mass in the universe to accumulate in it before exploding? That's...
  4. S

    Big Bang Theory: How Could Something Without Part Erupt?

    If it was an infitesimally small point, then the composition of said infitesimal point would be dimensionless, and by definition without part. How could something without part erupt? I understand that an infitesimal point could form a substance if there is an infinite amount (in fact, any...
  5. H

    The big bang theory and why i think its wrong

    The Big Bang Theory: The Big Bang Theory is one of many theory's on how the universe was created. From what i have learned of it, the universe was thought to have been created by to atoms (or particles) colliding together and causing a massive explosion which created the universe we know today...
  6. C

    Big Bang Theory: Fact or Fiction?

    I know the topic is incredibly original, but I was just curious as to how many people genuinely accept this as a feasible explanation for the creation of the universe. Personally.. I think (at least for a long time) that there is no way of knowing. I don't like how mainstream this theory has...
  7. G

    BBT's Portrayal of Nerds: Offensive or Accurate?

    As everyone here is into physics in some shape or form, I am sure everyone has at least heard of The Big Bang Theory by now. So, what is everyone's thoughts on the show? Do you like it, love it, got to have it? Who is everyone's favorite character, or favorite episode? Let's talk about the...
  8. N

    Alan Guth video on the BIG BANG Theory

    Excellent presentation: An introduction, or possible review, of the BIG BANG theory by an originator of inflation theory, Alan Guth of MIT: Note the video is in TWO PARTS...scroll down a bit for part II. 13 October 2009, Institute of Physics Inflationary Cosmology: Is Our Universe...
  9. U

    Is the Alternate Big Bang Theory Supported by Scientific Evidence?

    Hi everybody. There is a theory that the big bang was a whole bunch of matter from another reality, transported to this reality by an inter-demintional bridge. I do not agree with this. What does everyone else think?
  10. H

    What are the odds of falling in love with a physicist at an ice cream parlour?

    I heard this joke on the latest episode of the Big Bang Theory today and I thought I can share it with you. Penny tells the four guys this joke to pull their attention away from a new girl that just moved into a flat above them, and here it is: (A physicist goes to an ice cream parlour every...
  11. C

    Did Time, Mass, and Energy Exist Before the Big Bang?

    Please clarify and tell me where I am wrong. Before the big bang Time did not exist, nor mass, nor energy, nor velocity. Or did they? Thanks you for your help.
  12. 2

    Law of entropy vs. Big Bang Theory?

    Sorry if this isn't the right place for this post. Please do help me move this topic if necessary. I'm just a bit curious that the law of entropy states that the disorderness of a closed system will continually increase. However, the big bang theory says that the universe will expand until...
  13. F

    Did You Miss Out on The Big Bang Theory Last Season?

    I've been kind of in a cave lately, so I don't know if this is really news to any of you folks, but: I just found out about this awesome show that was on this past season. Guess the writers strike must have seriously dampened their viewer-ship. Take a look...
  14. Y

    Mathematica Mathematical proof of the Big Bang Theory

    Can anyone tell where I can find the mathematical proof of the Big Bang theory and by whom, I'm interest in the calculation only. If you have a scientific paper available with you please send it to me(yousifhot@hotmail.com) I really need it. Thanks a lot,
  15. K

    Question regarding the big bang theory

    How can the distance from the sun to the end of the universe be only 137 000 times longer than the distance from the sun to the end of the galaxy?
  16. A

    The Big Bang theory, and gravity

    Two questions and theories... #1. Gravity The sun, a nuclear reactor, holds all the planets in orbit. However, if it's force is strong enough to reach Pluto, billions of miles away. Why then, hasn't Mercury been sucked into the sun? My theory is, nuclear reactors, like a blown out candle...
  17. Q

    Big Bang Theory Self-Contradictory?

    Big Bang Theory Self-Contradictory!? There is so much hooplah floating around cyber-space. And there's way too much to talk about in terms of BBT. So, how is one to differentiate between truth and unfounded philosophy. And everyone seems to be shooting their mouth off lately as far as what...
  18. M

    Does the Big Bang Theory Break Down at the Planck Time?

    I know that Hawking and Penrose proposed that a singularity existed at the beginning of the big bang (and that they apparently changed their minds later). They extrapolated GR back and according to the mathematics, the density and gravitational field becomes infinite. But doesn't quantum...
  19. M

    Awesome geeky show: The Big Bang Theory

    Just thought I would tell you guys about this new show called The Big Bang Theory. It is very geeky, and there is tons of Physics/Math/Computer Science jokes everywhere. There is also plenty of Quantum Mechanics and other really good stuff, I think most of you would really like it... (i just...
  20. J

    Questioning the big bang theory.

    The big bang theory states: That at one time, everything that is known of our universe was once at a single point before it commenced "The Big Bang". Correct me if I'm wrong but, that means that every single particle in our entire universe could have been seen at some point in time after...
  21. ?

    In-Depth Guide to The Big Bang Theory

    Hi, I'm looking for an in-depth book discussing the Big Bang Theory. It is rather essential to me that it begins as a very basic explanation and then progresses into more interesting and more complex ideas. Any recommendations are appreciated, Thanks.
  22. Q

    The Big Bang Theory: Exploring the Beginning of the Universe

    What went bang to start everything?
  23. X

    Exploring the Science Behind the Big Bang Theory

    I was discussing the Big Bang theory with a friend, but couldn't answer a question he asked. Why is it that people believe that the Big Bang is true? Is there any scientific proof to it?
  24. D

    Big Bang Theory: Can Universe Expand Faster than Light?

    Let me preface this by saying that I know very little about astronomy, but this is a question that has been bugging me for quite a while. I've tried looking it up online and in books, but I can't find it directly addressed anwhere. My question is that if the universe began with a single...
  25. R

    Confirming the Big Bang Theory with QM: Dr Bob's Perspective

    I do not necessarly see what this has to do with a confirmation of the big bank theory. On the surface I would view this as a confirmation of QMs. It simple says that ocassionally you have enough KE to flip a spin of from the basic ground state. Maybe the "intensity" of the radiation might...
  26. vincentm

    Will cosmology ever confirm the Big Bang theory?

    confirm the Big Bang theory? I know that we currently have a lot of evidence to support it. But what I'm not sure of is why can't we see beyond the Planck Epoch 10^-43 or confirm that yes the universe did exist as a singularity beyond this point? And did this "singularity exist as some kind of...
  27. M

    Big Bang Theory: Exploring the Creation of Atoms

    All right, so what I don't understand about the big bang theory is that when it describes the creation of atoms, does it mean that the particles were already in existence and the explosin only made the particles come together? or were the particles actually created by the big bang? If the...
  28. Lisa!

    Everything about Big Bang theory

    I want to know everything about Big Bang theory. For example what were the clues which led scientists to this theory and how much they are certain of this theory. Big Bang theory says how this universe came to existence and started its expansion, now I want to know what will happen to the...
  29. Y

    Exploring the Big Bang Theory: Is Expansion Possible?

    this guy is one of those "modern science is wrong because i don't understand it" types. and this is the first time i can't see a flaw in his logic. what am i missing? * refers to the universe pre big bang
  30. Lisa!

    Does Big Bang Theory Allow for God's Existence?

    Do you think that Big Bang theory reject God existence? I don't know if you discuss about it before.But I want to know do you think that we couldn't accept Big Bang theory and God existence together?
  31. D

    I have a Question about the big bang theory

    undefinedundefinedundefined So. how can all the matter in the whole universe be compressed into one small little ball. all the matter in the UNIVERSE. it seems impossible. but I am sure a lot of u guys have a lot of ideas. maybe all the matter in the universe was under a great deal of force...
  32. phoenixthoth

    Is the Big Bang Theory Debunked?

    I came across this and was wondering if it was just hot air or if it was serious: http://www.rense.com/general61/bbang.htm
  33. M

    Big Bang Theory: What We Know So Far

    Big Bang...? ok so this is basically what I know of the theory can sombody point out if I'm go wrong with any of thi? ok so once there was an endless void of nothingness.there was no matter no particles nothing, and then a random explosion accured in the empty void and thus crated particles...
  34. T

    Did Supermassive Black Holes in Quasars Form Before Those in Galaxies?

    Edwin Hubble, 1929, formulated his hypothesis that the universe was expanding. George Gamov, in 1940’s, predicted the back-ground radiation, which was accidentally discovered by Penzias and Wilson, in 1965. However in 1969, Lyndon-Bell, laid the foundation that, at the heart of every...
  35. R

    What caused inflation in the big bang theory?

    What caused inflation in the big bang theory? I've read a few things that seem pure speculation designed to give a cause for something thought to necessarily have happened such as an antigravity force that faded at the end of the inflationary period. It seems too contrived to me.
  36. W

    Alternate Explanations for Redshift in the Universe

    Are there other ways to explain redshift than an expanding universe?
  37. R

    Two Big Bang Theory Vs Other Theories

    Hi, India rarely helps scientific advancement. Recently this country has made some wonderful advances in the field of missile technology and information technoloy. Their recognition has become strong now. Indians are now more popular in American due to outsourcing issue. Similarly some...
  38. J

    Can a Theory of Everything Exist Without Understanding the State of Nothing?

    10) How can Physicists propose a Theory of Everything without considering more closely the state of nothing from which energy was created? A second impasse faced by cosmological theory - insofar as it attempts to explain the origin of matter – is when describing the circumstances under which...
  39. J

    Searching for the Centre of the Universe: Is it at Rest?

    3) Why did it become unfashionable to mention the centre of the universe after the 16th century, when Copernicus placed the sun near there? Every body has a centre of gravity, whether it is a galaxy, a person, or a pebble. The universe had one when it first appeared: What happened to it? What...
  40. J

    Big Bang Theory: Exploring the Origins and Physics of the Universe

    Here follows the first part of the questions. Their appearance here is with thanks to Marcus and Nereids' encouragement:- Questions arise on what has been written for we ordinary people about how matter began – and on what has received little to no mention at all. To a cosmologist, these...
  41. J

    Seeking Answers to Geophysical Questions About the Big Bang Theory

    Can anybody suggest an avenue for resolving a predicament I face over big bang theory? I'm a geophysicist and work in remote areas, engaged in seismic data acquisition projects. I am fascinated by what I read on theoretical physics, and the fascination is focused on the (so far unsuccessful)...
  42. R

    Precision of The Big Bang Theory with John Gibbin's "In the Beginning"

    During the last few years I have read a number of books on The Big Bang including recently one By John Gibbin; "In the Beginning." Most if not all of the books mentioned the precision with which the initial values of some important parameters had to be for the universe to have formed as it has...
  43. W

    Reasoning behind the big bang theory

    [SOLVED] Reasoning behind the big bang theory Is there are way to qualitativly explain this, or is the math beyond most people? I understand that according to this model, the universe expanded from an unimaginably tiny particle with unimaginable mass desity, and that during the first fraction...
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