How could the universe expand faster than the speed of light? That seems impossible!
- asks Paul
Joshua J Romero • July 9, 2007
![[CREDIT: NASA/L.BEWLEY]](https://scienceline.org/wp-content/uploads/2007/07/timespace.jpg)
[CREDIT: NASA/L.BEWLEY]
In science fiction universes, traveling the galaxy is a snap – just engage the “warp” or “hyperspeed” drive, and off you go, cruising the cosmos at several times the speed of light. But back in reality, we’ve all been taught that the speed of light is a strict traffic law that can’t be broken. This is true, but slightly misleading.
Einstein’s theory of special relativity, first published in 1905, asserted that the speed of light is a constant (300 million meters per second), no matter who measures it. It’s always the same whether you are in motion or at rest. This line of thinking is a lot different than we’re used to experiencing. For example, if you try to measure the speed of an oncoming car from a moving vehicle, you end up getting the combined speed of both cars. This is why cops have to stay parked. Light is different, because no matter what you’re doing it always goes the same speed.
The speed of light affects us more than we realize – it helps us understand the difference between cause and effect. If things could move faster than the light we see them by, we’d be in for weird experiences. If you were a catcher trying to catch a superluminal fastball, you might feel the ball hit your glove even before the pitcher starts his wind-up: The effect before the cause. That’s because the image of object would be traveling at the speed of light, trailing the faster baseball like the slower sound of thunder trails after the image of lightning.
Now that we have a taste for Einstein’s theory, we know that baseballs don’t go faster than the speed of light. But is there anything that can? It turns out that the speed of light is only a limit on objects – like baseballs – as they move through space. The movement of space itself, however, can make the speed of light seem slow.
Right after the Big Bang, the universe had a monstrous growth-spurt called inflation. The whole thing was over in less than a trillionth of a trillionth of a second, but the universe grew exponentially in that brief blip, repeatedly doubling in size. At the end of inflation, although the universe was still smaller than a car, the outer edge had traveled many times faster than the speed of light. Since then, the universe has continued its expansion, but at a more reasonable, steady pace.
This ultra-fast growth seems to contradict what we’ve just discussed, but it makes sense if you understand the distinction between expansion and motion. When astronomers say that the universe is expanding, they’re talking about the rather abstract concept of space-time. Basically, space-time is the three physical dimensions of our existence-length, breadth and depth-combined with the additional dimension of time; think of it as a wire grid that connects every part of the universe to every other part. When we say an object has motion, we’re referring to its change in position relative to the space-time grid. The speed of light is only a constraint for objects that exist within space-time, not for space-time itself.
To better visualize the theory, astronomers often illustrate the expanding universe as a loaf of raisin bread rising in the oven. The raisins are galaxies and the rising dough represents space-time. As the dough expands, the raisin galaxies find themselves farther apart from each other, even though they are not moving relative to the dough between them.
Now let’s imagine that there’s a beetle in the loaf and it starts crawling toward a faraway raisin (don’t worry- we’re not going to eat it anyway). The beetle represents anything within space, such as baseballs, spaceships or photons. When the beetle burrows through the bread, he is moving relative to the dough, and all the other raisins. The speed of light limits how fast the beetle can travel, but not how quickly the bread can rise. Just because the expansion of space can break the speed limit, it doesn’t mean that we can go faster than Einstein said we could.
So, while the speed of light remains an unbreakable barrier for those of us within the universe, it can’t limit the expansion of space-time itself. The universe keeps right on expanding, but the speed of light limits how much of it we can see, and how fast we can move. It may not be fair, but that’s physics.
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About the Author
Joshua J Romero
Josh comes to science writing in New York City after studying astronomy and physics in Arizona. While he misses never wearing real shoes, Josh relishes the opportunity to read about science, politics, arts and culture on his daily subway rides. A former college-radio DJ, he is often found late at night in a half-empty, downtown bar listening to a noisy, experimental band with no record deal. He is fascinated with the boundaries of science, where it must intersect with politics, art, religion, or human nature.
198 Comments
Cops don’t have to be parked. Some of the modern radar can calculate cop car speed plus / minus your speed and find your relative speed.
I thought light was only a constant in a vacuum?
you all need to get a life
I don’t understand why they compare the expansion of the universe with the loaf of bread. There must be a better logical and sceintific explanation what are the forces behind the expansion of universe. There must be forces that affects space and time. These spacetime forces must be atleast explained than comparing to the raising of the dough in which the microrganism is converting some indregient in the dough that produces gasses that cause the expanding of the dough. Besides what is these spacetime force that causing it to expand and not contract. These are my 2 cents or so.
“If you were a catcher trying to catch a superluminal fastball, you might feel the ball hit your glove even before the pitcher starts his wind-up: The effect before the cause.”
Yeah, and what then? This is already true for the sound. If the ball travels faster than the speed of the sound then I feel the catching before I can hear the hit. What is the difference with the light? I catch then I see. It is the same.
“As the dough expands, the raisin galaxies find themselves farther apart from each other, even though they are not moving relative to the dough between them.”
Yes, they do. This is what we call moving. Getting closer or farther. Look at the dictionary.
Space-time is something we imagine not something that exists. It is a model of our actual knowledge. Something that doesn’t exists just can’t expand. The galaxies are the ones who are moving from each other. It is that easy.
And they do that faster than the light. The final limit of the speed of the light is an assertation not a fact. And it is bad assertation.
Suppose that we have two rockets launched from a planet in opposite direction. They travel 0.7c from the planet. Which is possible, isn’t it?
Then they will move with 1.4c compared to each other. And you remove the planet and they still have 1.4c. Does that mean that we have another fresh bread?
Who is to say that gravity can’t be infinite? Einstein couldn’t comprehend this If gravity is infinite, space, time, mass, and speed could be infinite. So can the speed of light. The question is, can the speed of consciousness overcome the speed of infinite mass, time, and space. The answer is no. Let us assume that the expansion of our universe is at exactly the speed of light right at this instance. That would mean that everything had infinite mass, gravity, space, and speed. Would not everything we understand now be equally paradoxical? It would also mean that nothing we can conquer could explain the real because of our limited consciousness. In other words, how could we explain what we cannot project or predict. Now that we have discovered the neutrino has traveled seemingly faster than the speed of light how can we predict forces act in similar ways in which we have recently imagined?
Hello,
if the universe is ~13.75 billion years old and a region visible from earth is a sphere with a radius of about 46 billion light years with objects in different ends (an yet Earth isn’t the center of the universe). So the logical questions now would be to ask – how is it possible for objects (lets say object A is our galaxy and object B is the galaxy somewhere near the end of our visible radius of 46 billion light years)?
Ok, for worst scenario we could assume that those both objects since big bang, are moving in opposite directions (this is hardly possible, since we take distance of radius, not diameter, but nevertheless that won’t change my point). So we get that these two objects from starting point moved approximate 23 billion light years in only 13.75 billion light years. We get that minimum speed required for such result is that both these objects would move from starting point with speed of ~1.67 of light speed all those 13.75 billion years (notice that this math was done in worst possible scenario).
In conclusion I can assume that either the age of universe is incorrect, either the speed of light is not the fastest possible speed in accordance between one moving and one not moving objects.
The argument of expanding space is not acceptable, because the speed is measured by the time and the distance between object’s start and end points (it doesn’t matter that at beginning planned distance was 1 and at the end it became 1.7), in the end I will count my speed = distance/time and distance would be taken 1.7.
The spacetime is just one modern false belief, it doesn’t exist. It was made mixing the, non relativistic, Lorentz’s aether with Galileo’s relativity. Given the absurdity of this invention, its consequences are absurd too. Consequences are the paradoxes, among another absurdities. Try to wake up, if you can, if your brain, good energy saver, allow you do it.
I thought Joshua’s article was very lucid. I don’t know why all the comments, particularly like the last three.
Please help me understand this: in the expansion (inflation) of it all since the Big Bang, with everything traveling away from everything else light dots on the surface of an expanding balloon, why do we see things out there? It all should have begun traveling at faster that light (being space-time)and how can we see things now, even after some slowing has occurred….? Thanx…
It’s premature, if ever possible, for humans to try to understand and explain the universe just because we came up with some theories about light and ideas about space-time. In fact, these are just illusions based on our sensory experiences and have nothing to do with what’s really “going on.” This is partly why we can’t see beyond the so called big bang, which is nothing but a dead end in my opinion and doesn’t explain anything. And, needless to say, notions about creation are just another layer of our ignorance.
Universe is expanding. Because it had to accommodate the whirling masses that are expanding. This expansion may stay when some stars quickly die out, reducing the mass content. Light is not a limiting factor for universe as it is just a transition medium between mass & waves. What we see is 180 plain. Expansion is 360 surrounding. Seeing is experiment. Expansion is an inference / imagination. Ageing is expansion. Death is extinct. Mass expands, Universe expands – simple is it not?
Now, I know that much smarter men than me are working on this, but I gotta say, it seems pretty ad hoc to separate a speed limit for objects in space from a speed limit for objects in space while it’s expanding which it always is. This sort of negates the speed limit if the space a hypothetical object is traveling across can also expand while it’s traveling. Good example, the light from objects further away in light-years than the age of the universe has, effectively, traveled faster than the speed of light. Average speed, do keep in mind, is distance traveled by time spent traveling; if greater-than-light speeds relative to each other are attainable by galaxies, then greater-than-light speeds are attainable in the universe. Seems to me that insisting on an absolute speed limit proven not-absolute by splitting hairs between objects’ speed relative to each other and objects’ speed relative to each other is a pretty shaky definition for having followed conventional mathematics to scales beyond their utility. More likely one of our assumptions (cosmic speed limit, age of universe, distance of objects) is off and we don’t have the tools to verify yet.
Sorry, justification, not definition.
I am a novice but find this all fascinating. I was reading up on Neutral Density Filters for cameras and their effects. If we were veiwing the universe in a similar way could this explain why we cant see dark matter?
I may be off topic, and could be grasping at straws, yet I am building my understanding of physics.
According to Einstein’s Theory of Relativity, e=mc2 and in that philosophy, when an object nears the speed of light, its mass becomes infinite (mathematically). So, after the big bang, objects move at most the speed of light, yet time-space speed is limitless(wondering here)? So ergo, why is the mass of Earth not limitless after achieving the speed of light, as consequence of the Big Bang?
So there are a few things I would like clarifying. (If I miss somthing obvious please correct me – I am no physicist).
What lies outside the universe?
If it is nothing, then how is empty space nothing?
Where is the proposed start of the universe?
Have they located this and if not…why not?
If outside the universe is nothing, then how can something spring into existence from nothing?
Suppose there is nothing outside of the universe…yet our universe, from concentrated matter has unexplainably exploded into existence and continues to expand, without drag (thus explaining this movement faster than light), into nothing. Surely this would suggest it is likely there are more than one concentrated matter explosions probable, which will expand through nothing (considering gravity should not be strong enough to pull this back[??]).
…
What would happen when they hit one another?
And if gravity pulls the outskirt of our universe back before this happens, how?
Why can’t you travel faster then the speed of light yet the universe can?
Is what lies “outside of the universe” a vacuum or something; pulling nothing into nothingness, faster then the speed of light can reach us – leaving no visible trace of the universe’s edge?
This just does not make sense to me and I would greatly appreciate someone trying to make more sense of this without saying:
“it’s just physics and therefore it’s fact”
And just on more thing….
That picture at the top, I’m assuming this is not the actual proposed shape of the universe, merely a image to show the general gist of things?
Thanks
If universe (alongwith its galaxy stuff) is expanding in above-light speed then i think we would not be able to see other galaxies (light stuck in between?) Looks like science will repent its theory in this case when come up with something new
Given that the universe is expanding at greater than light speed and the galaxies are further away than the age of the universe, one could conclude that we are not seeing the galaxies at all but merely the light that is left it their wakes that hasn’t all completely passed us by, since the galaxies have been generating light far longer than our snapshot of observation time. They may not even exist at all.
AS we are measuring speed of light in this Universe and we are present in this Universe, we will end up with a wrong value because as per Einstein’s theory of relativity, we can not measure correct speed of a moving object unless we are steady. But actually we are also moving with this expanding Universe. So we will calculate wrong speed of light.
Einstein was a great mathematician but a lousy astrophysisist. His E=mc² helped us to understand a lot but the other theories have misguided us. He was unhappy with space till his death bed! The constant for light applies to our local galaxies and our position in the exploding universe. If you axcept that the pressure in the centre of any explosion is more than on the outskirts, you will agree with this. Therefore we can do away with all the warped theories of time-space and concentrate on mechanical physics. Mechanical physics, in turn, has do do with real matter. Anti-matter, dark-energy, gravity, have laws beyound that of our current thinking. We need to explore the mathematics of “stuff” where bosons (gravitons) travel beyound the speed of light and you will see the universe is easier to understand. RRG2013
The confusion many of you are having surrounds the rate of expansion of the universe. Even though the universe is expanding at a rate that is greater than the speed of light, that does not mean that distance between any two galaxies is expanding at that speed.
In a extremely simplified example, lets assume for the moment that the universe was flat, with a width of 47 billion light years. The expansion rate is a collective expansion of all space between the two end points (edges), based on the total width of the universe. An expansion rate greater than c is due to the fact that all of space is expanding equally. The space between two galaxies, such as the Milky Way and the Andromeda galaxies, is substantially shorter. This means the rate of expansion between these two galaxies is also substantially smaller.
(Galaxy Separation / Universe Width) * Rate of Universe Expansion = Rate of Galaxy Separation Expansion.
Now, these figures are complete guesses, as I don’t know the real numbers.
(2.52 million LY / 47,000 million LY) * 3.56c = 0.00019c,
which is approximately 57.26 kilometers per second. This no where near relativistic speeds, and is why we can easily see the Andromeda galaxy, even with the universe expanding.
The current expansion rate of the universe is 74.3 +/- 2.1 kilometers per second per mega-parsec. Since every mega-parsec is expanding at that rate, we get the net effect of the universe expanding at a rate of 3.56c (approx., based on 47 bLY.)
The idea that all of space between objects would be expanding at a rate greater than speed of light would have huge implications on our own observations. Everything would be black, as the sun, moon, planets, and stars would have quickly expanded away. Even our own bodies would be torn apart, the atoms separating at the same rate.
Another thing to consider is that we are looking at the light from objects, where they were at when the light left them. Those objects have since moved, due to their own direction and rate of motion, and the rate of expansion of the space between us and them.
I believe that when the source of light is moving (expanding) faster than the speed of light, then that light is not now stationary, or even moving backwards (which would be a huge discussion all in and of itself). The light would still move at the speed of light, as it has to do because that is it’s law. It is just a “thinner” force, thus producing different spectrums of light than it would on a stationary object. So the light we see from distant stars that are moving away from us faster than lightspeed, we just see a weaker, thinner light from where that object was when the light was emitted. Also, if an object was moving toward us faster than light, the image would be blocked from us, as it surpasses the light it emits. So lets say a planet is moving toward the earth faster than light, we would not be able to see this unless there was a way to get a different angle on it, but we would only see where it was, not where it is. In a direct line of sight, the planet would be invisible to us. If said object had been moving for billions of years, and you managed to get behind the planet, I would assume it would appear that from where the planet came from it would still be coming toward you, at least in some aspect. Pretty mind boggling if you really sit and think about it. That’s just my take on one situation with the speed of light.
Brent, i would like to comment you if I can (I’m once again sorry for my lack of knowledge in physics, since I’m IT analyst, nevertheless I would like to get your response):
“The idea that all of space between objects would be expanding at a rate greater than speed of light would have huge implications on our own observations. Everything would be black, as the sun, moon, planets, and stars would have quickly expanded away. Even our own bodies would be torn apart, the atoms separating at the same rate.”
1. Why it should be black?… – how come we couldn’t see it as a film with delays (at some the point of the observed object, which was in certain position and after a wile it got further moving in the speed that is faster than light – we would see its position at movement moments, but with delay)?
2. And about the “our bodies torn apart” – we have an example, when our planet Earth is moving at the speed, which we can’t even reach inside our planet, but still – we don’t fell that speed because of gravitation.
If the edge galaxies are traveling at the speed of the light or over then our universe is nothing more that big fat zero!That then may explain something out of the nothing! here we come the Noble prize :))
Cheers
OPS!
If the edge galaxies are traveling at the speed of the light or over then our universe is nothing more that big fat zero!That then may explain something out of the nothing! here we come the Noble prize :))
Cheers
PS:I meant the length contraction and infinite mass then ?is that true??
Various physicists have posited sizes of the inflationary space bubble that vary by astronomical orders of magnitude. It’s good to have faith. Given physicists posit the big bang to have sprung from a singularity, how could “space” have inflated faster than the speed of light, when there was no second body “out there” to define the space between the singularity and the second body? Space as defined in the simple illustration below is the distance between the two points. If one point is a singularity, space does not exist as at least two quanta sized bodies would be needed to define space.
. space .
no space . no space
I’d like to start by saying that I’m not even close to an expert in this. These are the theories as best I understand them.
To go faster, you need more energy. The faster you go, the more energy you need. When you reach the speed of light(infinite speed), you’d need infinite energy. Try filling your gas tank and driving at 10mph until it’s half empty; then, drive back at 50mph. You’ll run out of gas long before you return to that particular gas station. Lighter vehicles require less power to move that’s why a motorcycle will accelerate faster and go farther than a car with the same amount of horse power and fuel. Since space has no mass, it requires no energy to move; therefore, E=MC2 doesn’t apply because M=0.
The thing about the galaxies moving away from each other faster than light seems to have been misinterpreted in several of the posts that I read. The “faster than light” part is meant to represent relative speed, not absolute. Thus, if two things are moving away from each other both moving at half the speed of light, they are moving away from each other at the speed of light even though neither object is going at that speed. In other words: let’s make the speed of light 100mph; thus, if I’m in a vehicle travelling east at 50mph and shoot a beam of light west, the rationale is that that light would move west at 50. It won’t. It’d move west at 100. This will also be true if my vehicle is travelling 10 or 20 or 70. This will increase the distance between me and the light at 150 or 110 or 120 or 170mph, depending on the speed of my vehicle.
In my utterly unscientific opinion, there seems to be some sort of mechanism that only asserts itself at the upper limits of intensity. My intuition links this slowing of time around fast moving stuff to the same effect that happens near black holes. Don’t know why, just a gut feeling.
It is my humble opinion after reading a lot of these pseudo-intellectual comments, that God must get a regularly good chuckle out of the ignorance of Man’s understanding of His Creation. Because, you see, you cannot come to a proper and accurate conclusion to anything when you leave out the most important factor.
Nice site I like the information you have, but do you ever
update it?
ENERGY SPEED MASS
Mo
m = ———— { mass equals Mo / Kinetic mass equals Ko }
1- (v2/c2
D = v X t
KAWECKIUNIVERSE
If the universe expanded faster than the speed of light how can the age of the universe be calculated?
Hawkings says that in ten minutes the universe had expanded thousands of light years. Someone trying to calculate those ten minutes of expansion would get a result of thousands of years. So the 13.7 billion years calculated as the age of the universe are totally wrong. I’m not talking about religion here.
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Questions? 1) How hot was the leading edge of the expansion? 2) How would the heat energy disperse if there was nothing in front of the leading edge. (no area to cool) 3) Could that thermal energy be traceable even now? Thanks.
Nothing to add for now….I just read this whole thing in one go and need to lie down, or take a vacation. I’ve been on the net since it’s inception, I’ve been EVERYWHERE on it,…(a trip to Mars would be a let down in comparison), and I’ve never seen such interesting and intellectual responses all under the one topic. Just wanted to thank the contributors.
Rik Crarke, I will briefly explain why religion over science is wrong. Death is humanities greatest fear, driven deep into our inherent subconscious, so religion is mans way to explain death as our minds cannot cope with it, it is actually two of the four main meanings we might find in death (afterlife, reincarnation, possible immortality through science, and legacy) which is the reason it was inherently created, all religions share this. religion states some interesting “facts” to explain away proven science. religious scientists say that dinosaurs did exist (as fossils indicate) but that because the earth and indeed the universe is only six thousand years old that means that dinosaurs and humans co-existed, and that that is where the legend of dragons comes from. Religious scientists say that because biological systems are too complex to have evolved, that means God obviously must have created them. one relevant to this is that we can see light from distant galaxies just as Adam and Eve could at the beginning of the universe because (you might want to sit down) the speed of light is not a constant. another is that because their was no evolution, Neanderthals did not exist, they were simply disfigured humans. all of them. at this entire period. one explanation for radiocarbon dating is that because the flood scrambled the carbon atoms it doesn’t work, the other is that it is simply made up by scientists, the government, and sinners and Satanists. also because DNA is so complex and we can read it, it can be nothing other than God’s signature. it does nothing. it is just a signature. and if you closely read the bible it implies and rather states that all water same from the flood, so by the logic water cannot be found outside our planet. fellow men and woman of science as well as non religious people please try not to urinate laughing, these are all serious beliefs held by leading religious scientists (not just any scientist who is religious, but those with primary degrees in religious sciences)
Norman Diaz, they would only get that result if they did the calculation based on the assumption that the universe had expanded at what we know as the current speed of light. Luckily scientists are not that dense.
The first comment says it all, it is the product of gravitational constant and the space impedance that is constant.
Reading about special relativity, this question comes to mind: How can the universe expand faster than the speed of light. If an object gains mass as it accelerates then shouldn’t the universe gain mass as it propels itself away from … itself at an increasing velocity. At some point the velocity will reach a point where it will take an infinite amount of energy to propel itself apart any faster, this point which would occur long before the universe could propel itself near or beyond the speed of light.
That is my reasoning, though the above is more a question, if someone would like to correct my logic and help me understand this email me at zdpressl@ncsu.edu. Thanks
I think everything we see happens in reverse.
Everything is expanding in all directions at the same time at tha speed of light.
Something that seems to move in a direction is in fact slowing down in relation to everything that is moving creating the impression of moving away .it slams on brakes and this takes energy and time.
Light in other words is standing dead still (the photons).
You cannot go slower than standing still and that therefore limits the relative speed of light.
Does this sound far fetched.kindly comment.
William.
I have begun to think of time in terms of being relative to the observer (even if that is an inanimate object). So if inflation happened in a trillionth of a trillionth of a second, my philosophical conundrum is “To what observer?” All matter was a part of inflation, right?
Which brings up a direct contradiction to this article I think? Matter was a part of inflation. Not just space-time.
So it seems matter moved faster than light-speed.
And it seems all time had to stand still relative to all matter in existence.
So back to where I am hung up… the trillionth of a trillionth of of a second is measured at what observer?
Easy. Stop being the beetle. We need to ride space like a wave. Silver Surfer style.
this is in resonse to Thomas Smith, July 9, 2007 at 11:55 pm
The speed of gravity is not faster than the speed of light. If that were the case then it would be possible to send faster than light messages by moving a piece of mass and detecting the gravitational perturbations at another point in space/time.
According to Special relativity information cannot be sent faster than light.
How can we be certain that we are not all shrinking inward from the “edges” like a boomerang, a bang cast us out and now we are shrinking inward making it seem as the edges are getting further away from us (earth).
Could it be that if space is expanding @ > c then at the since it is faster than c it is actually travelling backwards in time receding. This shrinking effect is expressed as “gravity” pulling everything inward like a drain in a toilet bowl?
Given the center of the universe (origin point of big bang) in spacetime as a constant with no motion in comparison to the matter moving through it, how close to the speed of light is all matter moving away from the center. And what kind of time dilation effects do we experience?
The universe can’t be expanding all away from each other unless we’re creating energy, whether you think the universe is relatively flat like a disk or round like a basketball. It doesn’t even matter if the universe has an edge and you think we’re moving away from the edge, everything cannot be moving away from everything else because in any instance there must be some kind of center. Imagine this,draw a circle on a piece of paper now draw a dot to represent the center,now and draw another circle between the dot and the outer circle. label the dot with an A, the first circle with a B,and the outer circle with a C; there are only two possible explanations for an expanding universe ,both of which are impossible. 1) If anything between A & B are moving away from each other then some of them would have to be moving towards A whereupon a huge cluster would form at the center and keep growing(if everything is moving away from each other then some of them have to be moving towards the center)that would be like inverse infinity! 2) As you go out from the center,everything is moving in the same direction outwards and everything has to keep moving faster then that before it in order for everything to expand from each other which is like impossible,the further you go out from the center in all directions the faster everything goes and has to keep accelerating ,I’m not a physics expert but it seems like something just isn’t right here, it doesn’t add up or make sense! perhaps I don’t know anything, please tell me where I’m going wrong.
Perhaps that’s what a black hole does, it consumes mass turns it into energy and keeps accelerating everything in the universe outward faster and faster lol our solar system would be moving a thousand times the speed of light
Or….lol the solar systems towards the middle of the universe are standing still and just appear to be moving away