My New Articles on Big Bang, Inflation, Etc.


Let’s start from the beginning. How did the universe begin?


How did the universe begin? We haven’t the faintest idea.



So what do we actually know? or at least suspect?




73 responses to “My New Articles on Big Bang, Inflation, Etc.

  1. Do you mean , before the space exploding expansion , space itself existed then some region of it started to expand ?
    If today they announce that Gravity waves proven then Field then Graviton , then gravity is a field not geometry ??

  2. But even that we cannot tell , right , we cannot tell if a volume of space appeared then expanded or a batch of existing space started to expand ?

  3. What is the meaning of “giant explosion”? One meaning of “explosion” is “a sudden, rapid, and widespread increase” — is Prof. Strassler an expert on semantics?

    • Explosions occur from a localized region and are driven by the release of pressure. The Big Bang was no such thing.

      • Consider “population explosion”, “information explosion” — the big bang was a non-localized explosion of spatial volume.

        • Do you really believe that if you say “the big bang was an explosion” that people don’t think about a bomb?

          Every video illustrating the Big Bang incorrectly shows it as a bomb. Every one.

          I’m trying to explain something that I think is conceptually important. Being semantic about the possible broadening of the meaning of “explosion” into other metaphorical situations, without actually looking at how people in fact misinterpret “Big Bang”, is not pedagogically useful. Should I start explaining all those semantic issues to the public? “It’s an explosion, but not an explosion like a bomb. It’s more like the population explosion, or the information explosion — a rapid growth, but not like a bomb.” Do you think that would really help?

          • Prof. Strassler: Good point. The concepts of bomb and physics are strongly correlated in terms of psychology. I concede that you are correct.

  4. From what I have read written by some experts in the field, like Alan Guth, it is inflation itself what happened and not an explosion.

    The point is that the inflation process in itself was incredibly fast (it is predicted based on certain evidence that at some point the expansion was faster than the speed of light).

    I have also read about some of the theories that predict that at the very early stages, the dimension of time was “transformed” in such a way that it was a dimension of space, so, at the very early stages of our universe, it started with four dimensions of space and later one of these dimensions turned into the dimension of time.

    It is my understanding that without the proper equations, this description by itself may not say much, even though I guess that an expert in the field of cosmology could work out the proper equations to validate or refute this assertion.

  5. Didn’t Neil deGrasse Tyson just present the BB as an explosion?

  6. Kevin Fairweather

    I look at it like this…. Our knowledge starts from a period where space/time is expanding from a very small, hot dense state. It is filled with energy which cools and forms the lightest elements.

    That is it.

    Anything before that time is speculation, we do not know where this hot, dense state came from or why. The “inflation field decaying”, quantum fluctuations, eternal inflation and so fourth or all very cool and good ideas but there is no hard evidence for them.

  7. One point of confusion with me is that talking about the beginning of existence (the universe as a whole) is like talking about the creation of a house with no building materials or a car with no parts–absurd. I don’t see how expansion of the local patch implies that the universe as a whole had a beginning at all.

  8. kashyap vasavada

    Matt: I agree with you pretty much. My guess is that the reason why important scientists call it explosion or big bang is that the only place where common people have seen a sudden expansion is when there is an explosion,chemical, nuclear etc. No body has seen expansion of space. So if after mentioning explosion, they just add a sentence that it is expansion of space it would be OK!

    • I think if you tell people something that they understand but that’s quite wrong, and then you say “well it’s not quite like that”, you are assuring that they will forever remember the wrong thing and never understand what you say after that. There are all sorts of statements about the universe that make no sense if you think the Big Bang is an explosion of stuff from a point.

    • They shouldn’t be targeting the common people anyway. It would be much better to assume your talking to a bright high school student whose interested in actual science and would be angry knowing that what was being said was crap. Such books in the hands of these kids would do wonders for the future of science. At the same time, discuss the inductive processes that led to the conclusions; science shouldn’t be taught as dogma to be memorized and parroted.

  9. Tony (Racz) Rotz

    Looking from the outside, I imagine a bubble popping into existence from some eternal timeless unknown.

  10. You say inflation started 10^-34 seconds after ……. After what ? Of what ? If there is no zero volume point that “”Exploded””then that figure is refering to what indeed ?

    • I didn’t say that. I most certainly did NOT say that. In fact I was extremely careful not to say it. Where, in any of my posts or articles, do you find that statement?

      And certainly there is no evidence, from data or from theory equations, that there was ever a “zero-volume point” from what the universe emerged. That’s a completely wrong interpretation of the Big Bang theory. Even the original form of the Big Bang theory, if you ran it backward, gave you an “infinite-density time”, not a “zero-volume points”.

      • OK , Sorry but i read that in so many places , I still wondering about one point , inflation of what ? A local existing space or a popped up space ?

  11. It is my recent understanding that when the density of the expansion diminished to a critical level, a change of state occurred that precipitated into the matter and energy which commenced baryogenesis.
    Is that true? If so, are there any good explanations or references to that hypothesized event?
    I am science-nerd layman who has been fairly well educated so far by the wealth of published explanations of Matt, Sean Carroll, and a host of others. Understanding the bigger picture is a continuous life-changing work-in-progress for me.

    • So first things first: the “matter and energy” terminology will only confuse you, and make it very hard for you to understand what happened. Please read this carefully.

      Nobody knows for sure why there are more baryons than anti-baryons in our observable patch of the universe. There have been many suggestions, even going as so far to suggest that dark matter is an exotic form of anti-baryon and that there’s actually no real asymmetry. Baryogenesis (the creation of the baryon excess over antibaryons, not to be confused with nucleosynthesis, the creation of nuclei from those baryons, which is well understood) is something about which there are many scientifically-grounded speculations, but very little knowledge. This may have occurred during a sort of phase transition (a change of state) but what type of transition, and at what time, is not known. It very probably occurred before (or while) the Higgs field turned on, though there are even speculations that it came later.

      I do not know of a good review article for a public audience on this subject. It’s all too vague, with a lot of guesswork and nothing concrete, at this point.

      • Thanks. I gave the link a quick scan and will read it later today with greater scrutiny. Concerning fields, I read a recent comment (don’t remember physicist ) who said he considered this a universe of fields rather than particles.

        I’ve kept a couple of your articles on virtual particles and particle/anti-particle annihilation bookmarked so I can refresh myself if ever needed.

        By the way, I so liked a comment you made in a talk radio broadcast with Sean Carroll a while back that I put it in a general quotes collection I keep:
        “The way I like to think about it, or like to pose it when addressing this issue with people who raise questions about the scientific process, is that one needs to understand that scientists in general do not trust scientists, they trust science. There is a distinction.”
        I hope I have permission to quote that.

        • Particles are ripples in fields; you cannot have particles without fields. However, you can have fields without particles. Most of my colleagues consider fields to be primary, and particles secondary. I do have some articles on this scattered around on this site. I have a series of posts on “Quantum Fields, String Theory and Predictions”, which you can find via google, but it’s quite sophisticated.

          Yes, you are welcome to quote me on that statement, which I have made many times.

          • “Particles are ripples in fields.” Hmmm, certainly a new idea for me–much different than the idea of fields coming from particles that I got back in my ancient undergrad physics. I’ll follow up with some reading. Thanks.

          • Curious about whether you see space as primary and fields as mathematical properties of space or fields as physically something. The concept space has a history dating back to the pre-socratic Parmenides who thought that “there is no nothing” and Plato who went in the opposite direction and reified space and made everything out of it. (Very tough stuff to think about–IMO.)

  12. If there is an infinite expance of space in which a certain point started to inflate , then our local universe should be started from the start of inflation without any reference to any prior point , right ?.

  13. Before Inflation every one agree that we can never know how can we decide if a sphere of space appeared from ?? Then started to inflate Or it is a particular region within an infinite space extension that inflated ….as I under stand this cannot be known inprinciple , right ?

  14. Then what do you mean by “Infinite density time?

    • What I said about infinite density time versus zero volume limit applies only in the old, outdated case that you naively assume the Big Bang is everything and you just run time backwards. If you include inflation and the new things we know about how quantum space can behave, then neither zero-volume point or infinite-density time applies. In any case, we do not know what preceded inflation, or indeed if inflation ever had something before it. The whole point of Figure 4 in my inflation article is that the process of inflation tends to erase that information, so it is going to be hard to learn it.

  15. It all a bunch of BS of scientists and cosmology specialists catering to the prejudices of their and the publics religious upbringing, of their desire for a beginning.

    The reason so many explainers of popular cosmology get details wrong when writing for the public has as much to do with them having fundamentally wrong ideas as is the difficulties of explaining things to the public.

    Inflation is an ad hoc creation of the human mind in a similar fashion as epicycles were created to account for the counterintuitive apparent retrograde orbital motions of the other planets when Earth was believed by popular prejudice to be fixed and unmoving.

    How come no discussion of the reason for the need for the creation of the inflation idea? Inflation was proposed because of the incompatibilities of the Big Bang expanding universe model with observations of our real universe; specifically the horizon and flatness problems.

    Furthermore, the Big Bang model is built from layers of fundamental mistakes. For example see and links within.

    All these crazy ideas proposed to fix the Big Bang expanding universe go away when one realizes that the cosmological redshift and cosmic background radiation and the flatness observations can be accounted for naturally with an infinite model that does not expand. Too bad today’ science is too afraid to admit to being wrong for most of them to give an inch to the possibility. Jobs and reputations are at stake, so instead we just get more and more layers of crazy epicycles.

    • I disagree with you.

      • Tony (Racz) Rotz

        Vincent is most definitely wrong.

        • Comments from the leader of the research team on the COBE mission support my position:

          Every culture has had myths about how the world began. In modern times, we are very technological and we have our scientific version. And it turns out that science’s version is more incredible than any myth anyone ever made.

          Then, last week, American scientists announced the discovery of radiation patterns in space that may mark the beginning of time itself. Said astrophysicist George Smoot, leader of the research team: “If you’re religious, it’s like looking at God. The order is so beautiful and the symmetry so beautiful that you think there is some design behind it.”

          Whatever caused the rapid expansion of the universe following the Big Bang–the same forces caused tiny ripples. Because if you try to do something too fast, you shake a little. God might be the designer.

          –Maclean’s, May 4, 1992 (the three above quotes are by George Smoot).

          “It is a mystical experience, like a religious experience,” Smoot said, reflecting the unscientific thoughts he had allowed himself in recent days, after the rigorous analysis of data was well behind him. “It really is like finding the driving mechanism for the universe, and isn’t that what God is?”

          –(San Jose Mercury News, May 12, 1992. Story by John Noble Wilford of the New York Times.)

          I heard that one person quipped something like this regarding Smoot’s comments: “Did you see if God was wearing a shirt?”

          • You seem very involved with this question of religion vice versa science. I don’t see anyone else here who is bringing in the topic of religion as you do. Seems like an old fight you are fighting considering the age of the quotes you have been enlisting. You and religion. 🙂

          • Margot, these recent news stories on the BICEP2 observations are extremely similar to the overreaching hype of 22 years ago when the cosmic background explorer (COBE) team announced their conclusions. The leader of that team said that it was like looking at God. This new team is concluding that they are seeing the beginning of the universe. I see neither in the data, just circular polarized light. I guess if I was a good little boy I would say that the Emperor is wearing clothes, but I just don’t see any.

          • It’s not circular polarized light; that’s inaccurate.

            It’s B-mode patterns of linearly polarized light — twists in the pattern of linearly polarized light. At large scales, it is difficult to create this pattern in all wavelengths without gravitational waves.

            In any case, this experiment has to be confirmed, and the interpretation of it has to be confirmed, before it is permissible to make any definite claims. Guth, Linde, and whoever the third person will be in the Nobel trio will have to wait at least until then.

          • Some physicists believe in God – whatever they mean with this term – some not. Some in a moment of elation reveal they believe in God. This is not surprising. No reason to be intolerant. You don’t know the truth. Life has such a span from grossest to subtlest. In this forum nobody introduced trhe term God, except yourself. This is a purely scientific discussion.

  16. Stanford Professor Andrei Linde celebrates physics breakthrough

  17. A layman question. If we define Big Bang as the expansion of space, what was the size of that space right when the expansion began?

  18. Ignore my question please. I got the answer. 🙂

  19. Prof. Strassler, would you comment on the cautious reaction of the Perimeter Institute?

  20. If the results stand, they are a landmark discovery. They provide our first look into energy scales that are perhaps a million million times larger than that of the Large Hadron Collider, and will greatly sharpen our theoretical understanding of events that happened perhaps a billionth of a billionth of a billionth of a billionth of a second after the Big Bang. The results also affirm, once again, the astounding power of mathematical analysis to lead the way into the most remote corners of creation. –Brian Greene on his Facebook site today




    Kind regards, GEN

    • I don’t see “god did it” as an epistemologically valid form of causal explanation. It’s only an arbitrary assertion because the cause can’t be found and the cause can’t be traced through to the effect.

      Science and religion are incompatible. Science seeks natural causes. If there were supernatural causes of some events, every scientific attempt to explain those events would fail. Science must use man’s only primary form of awareness: sensory perception. Religion does not want to be limited by the severe constraints of perceptual observation. BTW, the validity of perception is not a matter of faith as the pious love to claim: w/o giving the argument here, it’s axiomatic.

      I also see no possibility of the supernatural. Supernatural events involving an entity (miracles) would, in principle, violate an entity’s identity. The law of identity is a rock bottom axiom: if one doesn’t accept it’s truth, one can’t think anything definite about an entity. I believe this to be the same point of view about axioms as Aristotle used in his discussion of PNC (the principle of non-contradiction). For more about this, see the deepest atheist book I know of: Atheism: The Case Against God by George H. Smith.

      Also, I think the evolutionary biologist and author of the book and popular blog “Why Evolution is True,” Jerry Coyne, is writing a book which will attempt to blow away the whole idea of any compatibility of religion and science. Jerry Coyne’s blog is also a great place to hang out. Jerry even recently went so far as to read the whole goddamn Bible and a slug of theology books too.

      A last note. The pious seem to be aware that reason is their enemy and have developed–over many centuries–an enormous arsenal of attacks on reason. For example, some claim that the demand for evidence is itself arbitrary and based only on faith. These attacks remain enormously effective. It would take a whole book to catalog and refute these attacks. Unfortunately, the book hasn’t been written.

      To Matt (if you’ve read this far): I didn’t come here to discuss religion and I’ll make every effort not to do so again; it just stinks up your fine blog. You are a person who can say “I/we don’t know.” It’s not scientifically necessary to refute the claims of those who trot out their “god of the gaps.”

      • I don’t think that these questions have answers; and if they do, they don’t have scientific answers. We can pursue scientific avenues as far as we are able — and it is amazing how far they have taken us — but there will always be questions that they cannot answer, so there will always be gaps, and therefore always the option for people who are so-inclined to appeal to a divine force that explains what’s in the gaps.

        So let’s return to the science, where progress is possible.

        • Lots of people are agnostic and say: “God can’t be proven or refuted.” I’ve never seen anyone try to explain that. Really, epistemology is a valid and necessary philosophic science. It’s inescapable because every claim has two parts: 1) content or “what” is known and 2) “how” do you know it. We are not omniscient or infallible; considerations of “how we know” are vital.

          Anyway, today’s big issue is not whether natural science can answer every question; it’s whether reason can answer every question. The range of reason is a vital philosophic issue. We’ve seen the destructive results where some form or another of irrationalism has been allowed to grow like a weed in intellectual areas that have been abandoned by reason. Consider what’s going to happen when the religious right gets the political power to control science in universities. You can kiss goodby to research into the origins of life, for example. Forget about an objective cosmology.

          Reality is the only thing that exists and the only thing to know; there’s no reason to exclude reason (science in general) from any of it.

          • Mel. : Do not cofuse matters , who told you that believing equals to excluding reason ? That is your mirage , our only rejection is when science claims that it can know every thing , remember TOE ? This is nonsense , we hope that science limit itself to the observables that can be tested , ….
            I accept very much and admire the illustration in history of the universe post , science starts at HBB and any claim about what was before HBB is not science according to the scientific method itself.
            I would never accept any scientist telling me that nature generated the universe since inprinciple science can never prove that , if you do not agree then tell me about a natural material mechanism that is able to generate All the manifistations of the equations physicists use to describe the micro and macro realms ,,,,,it is not how to talk , it is how to reason.

      • Consider first his argument (apparently based on Branden’s view) that to assert that a god exists is contradictory (41-44). First, he argues that anything that exists has a specific nature. Second, he argues that a specific nature is determined by natural law. Third, he argues that since a god by definition transcends natural law, a god does not have a specific nature. Finally, he concludes that a god cannot exist since it has not a specific nature. Consequently, to assert that a god exists is contradictory. One debatable premise in this part of the argument is surely that natural law determines an entity’s specific nature.

        • Ok — enough. If the two of you would like to carry on this conversation, you are welcome to do so — elsewhere. This is not a post aimed at the discussion of the existence of God, gods, divine intelligence, creators, intelligent design, or Max Tegmark’s mathematical universe. So let’s stick to the topic. Please.

        • I think that God isn’t a topic to deal with, but consciousness is – a huge topic in science and unclarified. Then there is the question how the randomness of quantum physics which is basically the foundation of all physical and neurophysiological (!) processes, maybe even not only the foundation, more than that (see Vlatko Vedral’s Scientific American article, 2011), how that randommness can lead to meaning as ‘in the classical world, it goes without saying that each of us lives our life with purpose and meaning in mind, in what appears to be a linear time. To accept this as self-evident is crucial to getting out of bed every morning. Can randomness produce meaning, and if so, how?’ Those are open questions. I recommend to read some articles on that.

    Kind regards , Shami with respect.

  23. What this experiment might also be giving proof in an indirect way is about the tenet of the Information Theory tha information is never completely lost, even though it may be twisted, warped or otherwise “encrypted” by some process.

    Before the event of the first recombination, our universe was hot enough for electrons and other particles to wander freely away from the tigh grasp of nuclei, and free electrons means an opaque universe (light cannot get through) due to a high level of scattering.

    Until some years ago, it was argued that this opaqueness of the universe did not allow us to prod into the past beyond this point.

    But this prediction was a break into that line of thought, and now we can expect to make better use of predictions like this to prod even more into the very early stages of our universe.

    This is the outcome of experimental results validating theoretical predictions , but we still need here to have other teams running their own experiments to validate or refute these results and interpretation.

    Once we have other teams validating both results and interpretation, we will be standing on more solid ground to give much stronger support to this theory.

    Kind regards, GEN

    This is a scientific fact , take it or leave it .

  25. It is my understanding that keeping the conversation smooth and polite is a good way to conduct it in an orderly fashion that is consistent with the goals of this blog, a blog about Physics.

    Besides, we are all visitors, so, it is a basic rule that, as visitors, we play by the rules of the house.

    Kind regards, GEN

  26. Tony (Racz) Rotz

    Everyone has their own opinion of who or what or even if God exists, this is not the place to argue. I, as well, have mine. Let’s stay with science and especially Physics. Whatever you believe, it’s still remains HOW.

  27. Did you read the new article on the Future of Quantum Gravity?
    It discusses some interesting new views on locality….

    (…) Physicists are still actively debating the information paradox, but there is a growing consensus that its resolution will ultimately force them to relinquish a long-standing assumption called locality, the notion that particles only interact from adjacent positions in space and time. If particles inside and outside black holes can somehow exchange information, then information from evaporating black holes can be rescued. “Locality is a cornerstone of our fundamental description of physics today,” Giddings said, “but in my mind, the least crazy thing to do is modify it in some way.”

    Removing locality from particle physics could require a complete reformulation of the way Bern and other physicists calculate scattering amplitudes, because Feynman diagrams are drawn on the assumption that particles interact from adjacent points in space-time. Motivated by this problem, a group led by Nima Arkani-Hamed, a professor of physics at the Institute for Advanced Study in Princeton, N.J., recently discovered a much simpler approach to calculating scattering amplitudes — at least for a highly supersymmetric version of quantum physics. In the new approach, gluon scattering amplitudes can be computed by measuring the volume of an amplituhedron, a geometric object whose shape is determined by the number and properties of the gluons involved in an interaction. Locality does not enter into the calculation at all; the impression that collisions occur in space and time is merely a feature of the outcomes of calculations.

  28. Is the articele at Quanta magazine still valid?

    Sounds pretty weird:
    “If there was an amplituhedron-like object for gravity,” Arkani-Hamed said, “the idea would be, there’s this object sitting there outside space-time that gives you the answer to any scattering event.” Sometimes, the answer would be local, conveying the impression that space and time exist. For interactions with the unknown quantum system that constitutes black holes, answers would not depend on space and time.

    • It was all speculation in the first place; Arkani-Hamed is expressing a hope, but nothing’s actually been shown about gravity, despite that article going viral.

      But there’s no conflict between what they’re trying to do and inflation. These ideas don’t really affect each other.

  29. i think that the hawking’s radiation is being observed into the gravitational waves as echoes of the strongest ondulations produced in the spacetime be the inflattion-with speeds greatests that the speed of light;only inot the geometry of spacetime was inflated but the material l spacetime( quantic vacum) was inflated.

    congratulions for guth,linde and Hawking.
    the Works made by s donaldson in smooth toplogical geometr
    might be seen as the physics generated by the geometry and vice versay


  31. Matt,
    I don’t quite get how gravity can affect polarization of light at all.
    What’s the physics of it in simple terms ?
    Is it because at the time right after inflation the fields of gravity and electromagnetism were still ONE and further separation caused it or there are other reasons for that ?
    Please clarify my layman’s Q.
    Your fan, bob-2
    P.S. Sorry for the delay to coming back to your blog.

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