Big Bang Theory misconceptions

bigbangtheoryNot only is the Big Bang Theory a popular TV sitcom, but it’s perhaps one of the most well-known scientific theories of our age. Except, how much do you really understand about the Big Bang? I find that most people have a completely incorrect understanding of what the theory says, so I thought it might be useful to explore some of these misconceptions here.

The Big Bang theory is not an explanation of how the universe was created
It’s an explanation of how we find the universe to be today. I noted in my earlier article about the astronomer Edwin Hubble, that at the beginning of the 20th century, astronomers imagined that the universe was an essentially static object, with stars fixed in space. Hubble showed that galaxies are moving away from each other, and that the more distant the galaxies are, the faster they are moving.


The light from these stars took so long to reach us that the stars themselves have now moved much farther away.

Clearly this is a description of how the universe is today. But if we extrapolate the data back in time, we find that almost 14 billion years ago, the galaxies that we see today must have been compressed into a tiny volume – so small that normal matter like atoms couldn’t have existed in their current state. Once we get back that far in time we can’t really say what happened, because we don’t understand the physics of such hot, dense states. Yet.

Of course, scientists speculate about what that early universe was like, but the Big Bang theory itself doesn’t really tell us. That’s one of the reasons why the Large Hadron Collider at CERN is so important. It allows us to explore much higher energies than we find today – the kind of energies that were around during the first second the universe existed.


What’s a hadron? A proton, or hydrogen nucleus.

There’s a lot of other data that supports the Big Bang Theory too, like observations of the cosmic microwave background.

The Big Bang didn’t happen in one place
This is perhaps the hardest part of the theory to grasp. People imagine the whole universe being compressed into a tiny sphere and then exploding outwards into space, but this is entirely wrong.

First of all, there was no explosion. There was, disappointingly, no Bang. Instead there was an expansion, which is still continuing today (and in fact accelerating, thanks to something called Dark Energy).

Secondly, the Big Bang didn’t happen at some centre point of the universe. It happened everywhere simultaneously. There is no centre point of the universe. You can’t point at a cosmological map and say, “The Big Bang happened there.” So, 14 billion years ago, when the universe was very, very dense and hot, the whole thing expanded in every direction, at every point, at the same time. What happened before that? The theory doesn’t tell us.

Thirdly, the universe isn’t expanding into space. Space itself is expanding. Yeah, that’s weird, blame Einstein. What’s happening is that the distance between any two stationary objects is increasing with time, as explained by Einstein’s General Theory of Relativity. But don’t rush out and buy a new ruler – the rate of expansion is only 46 miles per second per megaparsec. Now in case your smartphone doesn’t have a handy conversion tool for this unit of measurement, a megaparsec is roughly 3 million light years, so this works out at about 2.6 E-18 miles per second per mile. Still baffled? It means that your ruler will still be accurate for at least several billion years, which will come as a relief for all “Back to School” parents.

The Big Bang Theory doesn't explain this.

The Big Bang Theory doesn’t explain this.

So forget explosion and think expansion. Yeah, I know that explosion is more fun, but there just wasn’t one, OK?


This never happened.

Space doesn’t have an edge
Cosmologists don’t know how big the universe is, but the best data indicates that it’s infinite. This isn’t a guess.

We can’t see anything beyond a certain distance in the universe. That’s because the light travelling from the most distant stars has been travelling for nearly 14 billion years, and that puts a limit on how far we can see. As the universe gets older, light from ever distant objects will reach us and we will be able to see further. But we’ll have to wait a long time before we can see a lot further.

So how do we know that there’s anything beyond the distance we can see now? It’s because wherever we look in the universe it all looks the same – not in detail, but in broad terms. Stars are stars, gravity is gravity, whatever direction you look and however far you look.

That tells us that the observable universe is nowhere near the edge of the entire universe. We can’t see any “edge effects.” So, the current data suggests that the universe is unbounded – or at least that the universe is much bigger than the part that we can see.


“So much for your stupid theory!”

By the way, the diameter of the observable universe is 93 billion light years, or 546,000,000,000,000,000,000,000 miles. That’s why cosmologists don’t use miles to measure things.

Question – how can the observable universe be 93 billion light years in diameter if the light from the furthest stars has only been travelling for 14 billion years? Surely that would make the observable universe 28 billion light years across?

Answer – it’s because of the expansion of space. In the time that the light from those most distant stars has been travelling, space itself has expanded, and so those distant stars are now much further away from us than when they first shone light in our direction. You see – the theory all hangs together, even if it’s a bit mind blowing to grasp.

28 responses to “Big Bang Theory misconceptions

  1. It’s mind blowing for sure, and so interesting. Our brains may have evolved to remember where the blueberry bush was, or how to take a tree limb and use it for our own purpose, but infinite or expanding space? There’s nothing in the architecture of my brain that can really grasp that. But that doesn’t stop us from staring out into space agog, thrilled with the mystery. Great post!

    • Absolutely, Craig. Science works by deducing what must be true based on the evidence, not what “feels right” or what “ought” to be true. Sometimes the conclusions make our heads hurt.

      As Richard Feynman, the late Nobel Laureate in physics once said, “If you think you understand quantum mechanics, you don’t understand quantum mechanics.”

    • if you can bottle space it’s not expanding

      • two boats floating in the ocean will allways drift apart an the ocean is getting no bigger.
        plus if you go into space and scoop some up in a jar ,put a lid on it and bring it to earth you know you put something in that jar yet everyone is unable to find it so there mus t no be anything in the jar
        and how can something that i’n’t there expand !
        It can’t Although i’m not a big fan if Alberts theory
        Space is not expanding so you are also wrong

        • JUST READ AN EXPLANATION OF RELITIVITY something about a train pluse of light from floor to mtrrored celine then back to flashlitebut the guy on the train passing by the guy outside the train standing stationary will see the light pluse as a blur while the guy on the train will not meaning the guy outside is seeing the same pluse of light at a differnt speed becouse the distance releitive to the passing train would change time for the guy outsideI ‘m not sure that is correct heres why If you gave both two stop whatches to both people and the whatches worked the same way they would both measure the time it took the pulse of light to travel its fixed distance , both would read the same concluding that no matter where you relitive postion to the light beam may be there has been no change in speed space or time to anyone yet the guy outside veiw of the light pulse is still buredbut proves nothing

          we are stuck on this speed of light thing the mechanical opperation of the universe would not change if there were no light why is it so important? If there was never any lighjt Alberts theory would be a lot differt the only contance would be the two stopwatches

        • You are making your remarks from the perspective of someone who has never travelled at speeds close to the speed of light (nobody ever has.) It appears to you (to everyone) that light travels instantaneously when you turn on your flashlight. Scientists working with high energy particles, such as the Large Hadron Collider at CERN in Geneva, deal with particles travelling at or close to the speed of light, and they can witness Relativity Theory in action every day. Einstein’s predictions describe the behaviour of high energy particles to a remarkable degree of accuracy.

          For a more accessible proof of Einstein’s results, I would recommend that you read about how two extremely accurate atomic clocks flown around the world were found to differ from each other by tiny amounts, in agreement with Einstein’s predictions. Even GPS satellites have to be corrected for time dilation effects, using Relativity Theory.

          The Theory of Relativity is a wonderful achievement of modern science, but as it deals with the physics of things we don’t experience daily as humans, it seems counter-intuitive.

        • Before the 20th century, astronomers pictured the universe as static. The astronomer Edwin Hubble first realized that space is expanding. He measured the speed at which distant galaxies are moving and discovered that everything in the entire universe is moving away from everything else. Einstein’s Theory of Relativity provides a mathematical framework to explain this expansion.

      • Unless your bottle expands at the same rate.

  2. Thanks for writeing back ,
    but you did not answer what is inside the bottle it of corse is space not the universe. the universe is made up of the TANGABLE thing that are inside space,. and although the tangable objects may be moving away from eachother this dose not prove that the space these objects are expanding inside of dose not prove that space it’self is expanding. Innkow light has a speed limit and I know about the big gun that smashes particals together and it is all great but the atomic clocks you were talking about is looking at only one side of the coin , so to speak

    if you have clock #1 on earth and clock #2 a couple of galaxeies away
    and both clocks read 12.00 and it took five clock minutes to get from one to the other , it would not matter if and object travels at 10x the speed of light or 1 mph both clocks would read 12.05 why? the speed that an obect is not going to change the time on those clocks,, and this would be the same with or without light

    • The expansion of space itself was first predicted by Georges Lemaître in 1927, by solving Einstein’s equations of General Relativity. The first astronomical observation of galaxies moving away from each other was made by Hubble in 1929. Hubble’s measurements confirmed the predictions of General Relativity.

      But you are right that an alternative explanation might be that space itself is static, and that distant galaxies are flying through space at high speed. One piece of evidence that this is not what is happening is that the most distant galaxies appear to be moving away from us at speeds faster than light, which is impossible.

      Another critical piece of evidence is that the further that galaxies are from Earth, the faster they are moving. This is not what you’d expect from, say, an explosion, where objects would fly away at the same speed.

      Yet another piece of evidence is that the expansion of the universe is actually accelerating. There are additional more subtle measurements that can only be explained by the expansion of space itself, not by galaxies moving rapidly through space.

      As for Special Relativity, and the two clocks you describe, Special Relativity predicts that time slows as an object moves faster, so the situation you describe would not actually happen. Atomic clocks have demonstrated this directly, and many other experiments have too.

      Relativity Theory predicts many strange results, such as the Twins Paradox, black holes, the expansion of the universe, and so on. It is a fascinating subject and there are some excellent popular science books available. Since you clearly have an interest, I would strongly recommend reading one of these books. It will explain the evidence in much more detail than I can, examine some popular questions, such as those you are asking me, and generally provide a fascinating insight into how the universe works.


  4. The mechical workings of a windup alarm clock is going to tik toc the seconds at the same rate no matter how fast it is moving I repeat the mechnical workings of a clock can’t be changed by something non tangable like the speed of any object

    • That is what we would think from our everyday experience of time. It seems to progress at the same constant rate. And yet, a mechanical clock travelling at a speed close to the speed of light, would actually slow down.

      How intriguing! I really would urge you to find a popular science book on relativity, as it is a fascinating subject.

      Briefly though, Einstein came up with his theory after scientists had made detailed measurements of the speed of light and discovered that it was always the same, even for two observers moving at different speeds relative to each other. Scientists were unable to explain how this could be true, according to the simple laws of motion everyone believed at the end of the 19th century. Einstein accepted the constancy of the speed of light as a truth, and from that deduced the Laws of Motion that must be true. His theory is based on two assumptions:

      1. The principle of relativity: The laws of physics are the same for all observers moving at constant speed relative to each other.
      2. The principle of the speed of light: The speed of light is the same for all observers, regardless of their motion.

      From these two simple principles, the rest of his theory follows. There’s a short introduction here: The diagram tries to explain why time slows as speed increases. But this is a very condensed article. You will probably still have just as many questions after reading the article. A book would be much better as an introduction.

      Special Relativity is usually taught in the final year of a Physics degree. It’s not an easy subject to follow. But it’s a fascinating one.

  5. Hey thanks for tailing to me about this I have a few more questions so please humor me..

    In this case model If the people on planet [A] and planet [b] had stop watches that and at 12.00 the watcthes were started and an oject was also thrown at the same time , close to the speed of light when it flew by the person on planet [B] that person was able to stop both stop watches and he stoped the watches at 12.05 both people on planet {a} and {b} would agree it took five minutesto travel that distance at the speed it was travelingwhy? becouse in this case model the only thing that is missing in this case model is a universe without light soif the person on planet {a} although not knowing the real speed of light threw the stone just under the speed of light they would still have to agree that it took 5 minutes …STAY WITH ME PLEASE, asecond rock is thrown at a speed just a little faster than the unknown speed of light ,, the second oject was trown at 12.00 on next day it would have to arrive at a time before 12.05 becose of the speed it is traveling over the same distance,, remember becouse there is no light there would be no way of knowing that the second oject was thrown faster than the speed of light STAY WITH ME.. knowning all this would the second oject get to the person on planet [b} and the stop watch stoped before 12.05 ,, the answer is yes!

    now do the same thing in a second case model with the addition of light would this change the clock times of the of the ojects {thrown at the same speed} as in case frist case model just becouse you add light an know the speed that light travels
    The answer is NO,, Why becouse the to people were only connected in a Mechanical nature an therefor both unaware of the final time of an objects arival.. until it got there,, Please write back,…

    • The situation is not as simple as you sketch it out here.

      “the person on planet [B] that person was able to stop both stop watches” – how? I am not being pedantic. How could a person on planet B stop a watch on planet A? He would have to send a signal to planet A to stop the watch, and that signal would take time to travel, so the time would be different.

      To do relativity calculations correctly, it is necessary to be very careful and precise about how and when and why things happen. The experiment you describe is actually impossible to do, hence your paradoxical conclusion.

  6. One last thing to consider

    Aworking mecanical clock would have enough energy in the spring to run the watch forword at normal speed lets call this a positive force,to slow the workings of the clock down you would need a negitive force , and some how some way aenough the faster the watch travels the more energy of negitive force would be created to counteract the positive force that keeps the clock running forward..

    If enough force could be to effect the forward movement of a working clock would that mean that the mechanlcal workings of a clock that was not wound up and have no positive forces driving it forward be subject to the same negative force created by how fast you are going , to move the mechnical workings of the clock in reverse …i DON’T SEE HOW SPEED COULD CREATED ENOUGH NEGITIVE FORCES TO RUN THE NON WORKING CLOCK BACKWARDS ,, IF IT CAN WHAT IS THE NAME AND COUSE OF THIS NEGATIVE FORCE .but if it dos’t then would that mean that there is not enough negative forces to slow down a normal working watch,,

    Regaurdless , of any answer It’s kind of like chess , you can make all the right moves and still not win the match,, talk to you later,,,

    • This is a misunderstanding. There is no force. It is not about energy, or springs, or anything mechanical. It is time itself that slows, not the movement of the clock hands. An observer travelling with the clock would not notice that the clock had slowed, until he returned to Earth and compared his clock with a clock that had remained on Earth.

  7. Alan, consider the following example. There are two scientists, A and B. A stays on Earth and has a flashlight. B gets in a spaceship and heads into space at half the speed of light (0.5c). After one minute, A shines the flashlight towards B. Question – how long does the light take to travel from A to B?

    Let’s first do the naive calculation, assuming that there is nothing special about the speed of light. From A’s point of view, the time taken must be one minute, because in one minute, B travels a distance of 0.5c and light travels a distance of c. From B’s point of view, the time is the same. This is the classical pre-Einstein view of the universe.

    However, there is a problem here. From A’s point of view, the light is travelling at a speed of c, but from B’s point of view, the light is travelling relative to him at a speed of 0.5c. We know from very precise measurements that this is not how the universe works. The speed of light is always c from the point of view of any observer. So the simple, naive model is wrong.

    To be continued …

  8. Let’s now take into account the fact that the speed of light is always c, for any observer.

    For A, the situation is the same as before. B moves at 0.5c, the light from the flashlight moves at 0.5c, so the time taken for the light to reach B is one minute, just like before.

    For B, things are different. B sees the light from A moving towards him at a speed of c (the speed of light is always c). Therefore the light is travelling twice as fast from B’s point of view as in our naive calculation. Therefore the light will arrive at B in less time than we calculated before. The time taken is less – time has slowed.

    Therefore, in order to keep the speed of light the same for all observers, time must slow down as an observer approaches the speed of light.

    It is the constant speed of light for all observers that causes spacetime to “stretch”.

    I agree with you that it sounds crazy. In normal life, we have no experience of such things. The speed of light is 186,000 miles per second, so even the fastest man-made vehicles travel much slower than this. Yet it is a real phenomenon, with an abundance of experiments that prove it.

  9. hummm,
    since the space ship ends up at half the distane to the one minute line why not just start the ship from there the same time you turn on the flashlight so that you cross the one minute finish line at the same . but if you exchange the flashlight beam for a rock traveling at the speed of light the ship could see the rock catching up to them and crossing the one minute finish line just as the beam of light would have ..

    at what point did time slow down for the ship ,rock,or beam of light ,,

    There is athird side to a coin the edge
    my universe without light was a representaion of alberts theroy an explanation to someone who has never seen light A Blind Man the speed of light and the rules that are governed by it are as useless as the the colrs blue and yellow to make the speed of green,,wouldn’t you agree,,

    • Problems: You can’t start the spaceship B from the halfway point at the same time as A turns on the flashlight, because B doesn’t know when that happens until the light reaches him. Again, I’m not just being pedantic, but describing the real situation.

      “A rock travelling at the speed of light” – no rock can do that. Because, Relativity.

      Time slowed for the spaceship as soon as it started to move.

      As for your last question – a blind man may know nothing about light, but that doesn’t change the way the universe behaves. Light does what it does regardless of whether there is anyone around to see it. Besides, visible light is just one part of the spectrum – we can’t see radio waves or X-rays, but we can make them and detect them with machines.

  10. why not two watches and a start time would sovle that problem,,situation sloved Iasume that the spaceship is just as quik as the light beam but can only top speed of .5cthey cross the finish line at the same time ,,,
    now you suold give that little ol’ rock a fighting chance,,, so what your saying is light in a universeal sense is pretty much useless becouse it dose not effect how the mechanical universe behaves and therfor unabble to change universal spacetime,,, how fast dose it take light to atchive it’s max speed it must take a small amount of time would it not? write back,,

    • “two watches” – OK, but it’s still not as simple as you think, because A sees a different result to B (both see the light move at the same speed, but they see each other differently).

      “light in a universeal sense is pretty much useless” – don’t know what you’re getting at here?

      “it dose not effect how the mechanical universe behaves” – rather, the behaviour of light is a feature of the mechanical universe.

      “how fast dose it take light to atchive it’s max speed” – light always travels at the same speed. It doesn’t accelerate from a standing start. Light is a wave, with no inertial mass associated with it.

  11. Is there any way offinding the second fastest thing in the universe or would that be such a large undertaking that it would take to long to find it ,and is this why the speed of light was used not just becuose it was a contant but mostly becouse of conveince

    by the way thaks for being a good sportabout the questions but you never said what would be inside the jar if you scooped some empty space put a lid on the jar would it just be a vaccum of empty space?

    write back

    • OK, so there isn’t a second fastest thing in the universe. Light travels at the speed it does because it has no mass. Anything with mass can approach the speed of light, but never actually reach it. As it gets faster its mass increases, so it becomes harder and harder to accelerate. That’s what E=mc2 is all about. So the speed of light is the universe’s speed limit.

      What’s inside an empty jar? Well, according to classical physics, there is nothing, but quantum physics tells us that even empty space is a buzzing soup of virtual subatomic particles that pop into existence for an unbelievably short amount of time before vanishing again. You can actually measure the effect of these particles, as it creates a minute force acting on the walls of the jar. It’s called the Casimir effect. The vacuum also contains its own intrinsic energy, related to the “dark energy” that you may have read about elsewhere.

  12. Then how can light very in intensity [briteness} it has no mass ,, mening , if a flash light with good batteries ware down the light becomes dimmer how do you change the intensity of light if there is no mass to light to take away from ,,but lets try that again
    What do YOU think is inside the jar not what do you think other pepole think is inside the jar,.. no pressure write back

    • Light carries energy, and different wavelengths have different amounts of energy too. So, X-Rays and gamma rays carry more energy than visible light, which in turn carries more energy than radio waves. Increasing the intensity (brightness) increases the number of photons, so more energy is transmitted.

      What I think is inside the jar is exactly what I described – a sea of virtual subatomic particles at a density so low they are not normally observed. There is a huge amount of evidence to support quantum physics. But don’t get the wrong idea – an empty jar is empty to most intents and purposes. It’s just empty space.

  13. It’s strange how I see a vitual sub- patrical that might be to small to interact with a photons of light , to prove E= mc2 is a lot of really smart vodoo only to be cursed by that old saying ,
    What’s the shortest ditance between to point , of course we will never know becouse there’s always a shorter distance or in this case a smaller partical that always seems to be in that pandora’s box full of paradoxx oh! by the way a new word to discrice an unfornateb behaiver allthough I’ll end up spelling it wrong ETHNICIST should be the replacement for the word racist be bouse it;s hard to say and sence theres on one race ,the human race being a racist would mean you would dislike the whole human race .. but thats the media for you maybe try to get it into that world dictionary besides 15 minutes of fame is still fame , till next time,,,

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