@Anphase the universe is expanding at a rate where light can not catch up to the outer border of the universe at its place where the last light source would be. but at the same time the universe expansion theory suggests that light sources like our sun are following this ever expanding border and eventually finding their place and staying their.
I have a question though. If the distances increases while the light is reaching from lets say a star, how do we know the star acutally exist right now? Maybe if we are up in space with a super fast space ship and wants to fly to a star, while flying towards it it slowly faints away, and when we get there it's gone. It wa sjust the light that was still there!
By the way, it is not 13.4 billion years, because that would indicate that the photon was emitted when the universe was 300 million years old (not thousand). It would be about 13.69-something billion years. But anyway (not a big deal), great video. Thanks!
@stuner760 Yeah I thought so too. Haha yeah I thought of that as well. But the reason I asked is because he says that there exists part of the universe that is outside of our 13.7 billion year light bubble. So I assumed from that that the expansion is faster.
Any it gives me food for thought and opens a possibility that travelling faster than light has always been possible which might be beyond our current perception.
dude, no planet of particle can travel faster than light. so as time proceeds, the distance between the photon and particle decreases rather than increase to 30M light years from 10MLY by the time photon travels 10MLY
@visu119 There is also nothing stopping the universe expanding faster than the speed of light. Although at any local point within the universe, nothing can travel faster than the speed of light, this is not true for the entire universe. There is no limit on how fast space can expand.
Why the universe is expanding faster then light or why its still expanding at all is still in speculation, but we do know that it is though, based on experiment and complex science and mathematics. Maybe you guys should become scientists to solve this huge questions, I know will.
as time goes on, the distance in front of the photon that it still has to travel keeps stretching into a longer distance. So how does that photon EVER get to us. I cant conceptualize this, can anyone explain?because it seems that every time he draws a diagram further in time, the distance in front of the photon gets longer.
This video sort of explains "inflation":( /watch?v=_LGia74lu70) ... Inflation as a theory is supported by non-uniform temperature in cosmic background radiation. I still don't totally understand but apparently no one really does.
Here is what confuses me about big bang theory. The objects in the example are 30 million light yrs apart yet the universe is 300,000 yrs old. Both objects originated at the same point. This means they appear to have traveled many, many times the speed of light away from each other. The explanation is inflation. What does that mean exactly? Objects cannot exceed the speed of light but the expansion of space can(or appears to)? Please explain.
@HigherPlanes I get that. I still don't understand how the two objects, originating from a single point, got 30 million light years apart in 300,000 years. Do you understand what I am asking?
@mrcoconutdick This is my understanding of inflation: Look at the big bang and inflation as the same phenomenon. Without inflation, objects really have no way of distancing themselves.
Let's assume you have two objects 1 light year apart and we can stop inflation, it takes light one year to travel from one object to the other. If you take another measurement in 1 million years, you can assume to get the same result. With inflation, distances increase, light travels more in the same time.
@Xernoxis - Oh, of course, hence the term "visible." Doy! Thanks for clearing that up.
Yes, nothing can be accelerated to faster than light speed, but if it's already going faster... Of course, the whole thing confounds me because velocity needs frame of reference to be meaningful, and that's hard to grasp in an expanding universe.
Hmm, I would like to make my research lab when I turn old. But the problem is getting materials for my research, especially about this subject. I'm from the Philippines. Well, I guess I would just update with the 3-dimensional world.
Good analogy maybe: The Photon travelling between the distant star and our eye is like a Marathon runner who starts a race, and then while running hears that the Begin line and End line are being steadily moved away from him in either direction by a mile every hour.
The idea of "expanding space" doesn't make any sense to me. Yea I know, it was Einstein who invented it and maybe mathematically it has its inner logic. But at the end of the day space and space coordinates are a human idea, an imagination, a thinking model in the first place, not a physical reality in itself.
"Expanding space" is like distorting the axes of a function graph in order to get a straight graph where otherwise a curve would be. Its nothing more than a cheap trick.
If the universe can expand at a greater speed than a photon can move, Light speed cannot be the fastest speed there is.
8.30 Surely it has moved only 10 million light years, but the sun as it's point of origin has also moved 10 million.
A person leaves their house, but the house moves and the path the person walks on streaches and the place sort also moves, the distance the person walks is set surely, total distance on arrival realtive only to the path and distination sort, not P.O.O.
in essence when some one asks how tall you are you are infinitely tall a 1.9m isn't exactly 1.9 he's 1.9000000335656 e.g so in essence he's infinitely tall between the 1.9m and 1.91m my point is that is how you must look at the universe to truly understand it its not infinitely big its bigger than any number we can fathom (graham's number) there is an edge to space there's not infinite darkness its basically a bubble and i believe its one of many bubbles a multiverse if you will
@wozzers2 I belive that the universe is wrapped around. Our 3-dimensional space I belive is the surface of a 4-dimensional sphere. The origin of the universe would be somewhere outside of our 3-dimensional space. So the edge of the universe, or the maximal distance away from our current position possibly would then be half way around the 4-dimensional sphere, half way back to where we are now. I don't know who came up with this theory but I think it's the most logical explaination. :)
@AX53B60 i think the answer is within the inner frontier i thinkwe have to look inwards to see outwards life is basically a fluke in my eyes i feel every galaxy has its habital zone some have several the universe just has tobe curved in my eyes it just has to be we will never ever be able to map it the vastness of our universe just humbles me everytihng in my life isn't even trivial compared to a universeal scale i hatte that its called universe its one many
i think i've worked it out the OU is to the whole universe isn't even what the OU is to a quark(smallest known elementary particle) it relatively is smaller i believe the inner frontier will allow us to learn about the outer frontier the OU is basically less than an atom relative to the Universe
Confuzzled. Does (is) space expand (created) between objects? or is it that it expands from the outer "layers" of the universe, taking the rest of objects with it?
I wonder how many thousands of galaxies leave our visible universe every day. probably millions whole civilisations lost for ever everyday and basically become non-existent to us
is there a mathematical ratio in which space is expanding? like you were saying about the photon taking 13.4 billion years to reach us from 46 billion light years away... what is the ratio?
So this means newer and newer light from that far away object will eventually never reach us? So.. deep space observation should get dimmer and dimmer, until we got all the light we could from that far away object. So the observable universe should be shrinking?? (aside from new emmiting objects).
if the expansion rate of space is increasing then wouldn't the strength of any force holding sub atomic particles together also need to increase at the same rate? (like running on a treadmill) but apparently these forces are constant?
@neutronstarx This is just a guess because I don't know but I think this might be a good anology / reason. Think of people in a vehicle that's going X meters/second. When you're in the vehicle it doesn't feel like you're moving even though you are. Then I guess the big bang expansion would be like having a car wreck and everyone flying out of the vehicle except not stopping. Some of the stuff flying out could be a massive black hole or it could just be big blocks of atoms.
if space is expanding and light is expanding... then so to is time. So what was initially going to take 10 million years to traverse will still take 10 million years to the photon. But to an outside observer it took 13.7 billion years.
At 5:48 you state that the photons emited from the period of recombination were done so at microwave wavelengths. This is not correct. The photons energy was much higher when emited, but have been heavily redshifted since, hence they are now in the microwave part of the spectrum.
How will you prove the 13.7B light year distance? You can use math to finagle it any which way you can (like Clint's chimp), and as one ape to another, "The fool! To think his ape's brain could contain the secrets of the Krell!" Jesus was a Krell!!
@Fentro Please read up on this before calling the people who came up with the 13.7 billion year numbers. Your claim is as foolish sounding to people who know what this is about as is the claim that fools think the earth orbits the sun. This is outside your knowledge. Calling astronomers and physicists fools is like calling a mechanic a fool when you know nothing about cars, but he's steadily tuning and fixing yours. Even your knowledge of Jesus is off. Saying to your brother, "thou fool," =fail.
It's rather ironic we call it the big bang considering Fred Hoyle, an advocate of steady state, named it sheerly due to the inaccuracy and ugliness of the name while he launched a media blitzkrieg against it.
This may be a dumb question: is the universe expanding faster than the speed of light?
Anphase 1 week ago
@Anphase the universe is expanding at a rate where light can not catch up to the outer border of the universe at its place where the last light source would be. but at the same time the universe expansion theory suggests that light sources like our sun are following this ever expanding border and eventually finding their place and staying their.
BEASTATHEISTGUNNUT 1 week ago
Comment removed
xcvsdxvsx 1 month ago
I have a question though. If the distances increases while the light is reaching from lets say a star, how do we know the star acutally exist right now? Maybe if we are up in space with a super fast space ship and wants to fly to a star, while flying towards it it slowly faints away, and when we get there it's gone. It wa sjust the light that was still there!
nils4545 1 month ago
Comment removed
ChillDudelD 1 month ago
Oh, well than there's your answer. :D
stuner760 1 month ago
If the universe is 14 billion years old how can something be 46 billion light years away from us?
lolwut162 1 month ago
@lolwut162 he explained that this whole time bro
najafnajafali 1 month ago
This photon seems like a swell guy!
novanovalove 2 months ago in playlist Cosmology and Astronomy
By the way, it is not 13.4 billion years, because that would indicate that the photon was emitted when the universe was 300 million years old (not thousand). It would be about 13.69-something billion years. But anyway (not a big deal), great video. Thanks!
yamenhawit 2 months ago
Wait, what's faster: the rate of expansion of the universe or the speed of light?
yamenhawit 2 months ago
@yamenhawit I thought they were the same?
but think of this...if the speed of light were faster..what would happen to the light?:o
stuner760 1 month ago
@stuner760 Yeah I thought so too. Haha yeah I thought of that as well. But the reason I asked is because he says that there exists part of the universe that is outside of our 13.7 billion year light bubble. So I assumed from that that the expansion is faster.
yamenhawit 1 month ago
42
kingpranw141180 3 months ago
Any it gives me food for thought and opens a possibility that travelling faster than light has always been possible which might be beyond our current perception.
visu119 3 months ago
dude, no planet of particle can travel faster than light. so as time proceeds, the distance between the photon and particle decreases rather than increase to 30M light years from 10MLY by the time photon travels 10MLY
P.S.MLY-Million Light Years
visu119 3 months ago
@visu119 There is also nothing stopping the universe expanding faster than the speed of light. Although at any local point within the universe, nothing can travel faster than the speed of light, this is not true for the entire universe. There is no limit on how fast space can expand.
Coppertunes 2 months ago
i did finally understand it! thanks! for the good video, im going to work with astronomy, and maybe search for life! that is my dream! :D
eirik230696 3 months ago
@Z2k11 Lol I meant " I know I will"
INMATE2468 3 months ago
As I keep telling people all along...
WE DON'T KNOW THE TRUE SIZE OF THE UNIVERSE!
and we may never know..
vlweb3d 3 months ago
Why the universe is expanding faster then light or why its still expanding at all is still in speculation, but we do know that it is though, based on experiment and complex science and mathematics. Maybe you guys should become scientists to solve this huge questions, I know will.
INMATE2468 4 months ago
@INMATE2468 Is Will nice?
Z2k11 3 months ago
as time goes on, the distance in front of the photon that it still has to travel keeps stretching into a longer distance. So how does that photon EVER get to us. I cant conceptualize this, can anyone explain?because it seems that every time he draws a diagram further in time, the distance in front of the photon gets longer.
moeisgreat 4 months ago
I don't get it! How can there be a distance of 30 million light years inside the universe if it could only travel a maximum of 300 000 light years
Socom1112 4 months ago
Hello Khanacademy,
Respectfully, I ask that you explain faster than light inflation of the universe?? I don't get that????
mrcoconutdick 5 months ago
This video sort of explains "inflation":( /watch?v=_LGia74lu70) ... Inflation as a theory is supported by non-uniform temperature in cosmic background radiation. I still don't totally understand but apparently no one really does.
mrcoconutdick 5 months ago
This was actually very poorly explained which is very rare for a khan video. The idea of relative velocities need not be so complex...
c00kiemonsters 5 months ago
Here is what confuses me about big bang theory. The objects in the example are 30 million light yrs apart yet the universe is 300,000 yrs old. Both objects originated at the same point. This means they appear to have traveled many, many times the speed of light away from each other. The explanation is inflation. What does that mean exactly? Objects cannot exceed the speed of light but the expansion of space can(or appears to)? Please explain.
mrcoconutdick 5 months ago
@mrcoconutdick No- if the expansion of the universe exceeded the speed of light, the night sky would appear pitch black.
HigherPlanes 5 months ago
@HigherPlanes I get that. I still don't understand how the two objects, originating from a single point, got 30 million light years apart in 300,000 years. Do you understand what I am asking?
mrcoconutdick 5 months ago
@mrcoconutdick This is my understanding of inflation: Look at the big bang and inflation as the same phenomenon. Without inflation, objects really have no way of distancing themselves.
Let's assume you have two objects 1 light year apart and we can stop inflation, it takes light one year to travel from one object to the other. If you take another measurement in 1 million years, you can assume to get the same result. With inflation, distances increase, light travels more in the same time.
HigherPlanes 5 months ago
It would be kinda trippy if there was only life on earth and no where else in the whole universe cuz that a lotto space
Honestyandyourself 6 months ago
Shouldn't the origin point of the big bang be considered the "center" of the visible universe?
Is the universe itself expanding faster than the speed of light?
One thing that makes this confusing is that (it seems that) there is no fixed coordinate system in the universe.
GlorifiedTruth 6 months ago
@GlorifiedTruth The visible universe is the light that has reached the earth. Nothing to do with The Big Bang.
Yes I believe that the universe is expanding faster than the speed of light.
That's the fun part :)
Xernoxis 6 months ago
@Xernoxis - Oh, of course, hence the term "visible." Doy! Thanks for clearing that up.
Yes, nothing can be accelerated to faster than light speed, but if it's already going faster... Of course, the whole thing confounds me because velocity needs frame of reference to be meaningful, and that's hard to grasp in an expanding universe.
GlorifiedTruth 6 months ago
Hmm, I would like to make my research lab when I turn old. But the problem is getting materials for my research, especially about this subject. I'm from the Philippines. Well, I guess I would just update with the 3-dimensional world.
niconikko 6 months ago
Thanks Sal. Still trying to figure out how special relativity fits into this whole picture. :P
nikanj 7 months ago
Now, from the creators of the award winning game The Big Bang, comes an expansion pack like never before
The Big Bang: The Universe
Explore new features like
*Life
*Everything
*Epic flying mounts
LidlFisken 7 months ago
There has to be intelligent life out there, I just know it!
IcarusTouma 8 months ago
Good analogy maybe: The Photon travelling between the distant star and our eye is like a Marathon runner who starts a race, and then while running hears that the Begin line and End line are being steadily moved away from him in either direction by a mile every hour.
How annoyed would that runner be? XD
Destro7000 8 months ago
ok so if i get it right spacetime (the universe ) can expand at a speed greater than the speed of light. is that right?
amidrastein 1 year ago
When you start feeling extremely confused about this, it's because you're starting to understand. Keep thinking!
KodierungHerz 1 year ago 27
The idea of "expanding space" doesn't make any sense to me. Yea I know, it was Einstein who invented it and maybe mathematically it has its inner logic. But at the end of the day space and space coordinates are a human idea, an imagination, a thinking model in the first place, not a physical reality in itself.
"Expanding space" is like distorting the axes of a function graph in order to get a straight graph where otherwise a curve would be. Its nothing more than a cheap trick.
Skandalos 1 year ago
If the universe can expand at a greater speed than a photon can move, Light speed cannot be the fastest speed there is.
8.30 Surely it has moved only 10 million light years, but the sun as it's point of origin has also moved 10 million.
A person leaves their house, but the house moves and the path the person walks on streaches and the place sort also moves, the distance the person walks is set surely, total distance on arrival realtive only to the path and distination sort, not P.O.O.
099749 1 year ago
in essence when some one asks how tall you are you are infinitely tall a 1.9m isn't exactly 1.9 he's 1.9000000335656 e.g so in essence he's infinitely tall between the 1.9m and 1.91m my point is that is how you must look at the universe to truly understand it its not infinitely big its bigger than any number we can fathom (graham's number) there is an edge to space there's not infinite darkness its basically a bubble and i believe its one of many bubbles a multiverse if you will
wozzers2 1 year ago
@wozzers2 I belive that the universe is wrapped around. Our 3-dimensional space I belive is the surface of a 4-dimensional sphere. The origin of the universe would be somewhere outside of our 3-dimensional space. So the edge of the universe, or the maximal distance away from our current position possibly would then be half way around the 4-dimensional sphere, half way back to where we are now. I don't know who came up with this theory but I think it's the most logical explaination. :)
AX53B60 1 year ago
@AX53B60 i think the answer is within the inner frontier i thinkwe have to look inwards to see outwards life is basically a fluke in my eyes i feel every galaxy has its habital zone some have several the universe just has tobe curved in my eyes it just has to be we will never ever be able to map it the vastness of our universe just humbles me everytihng in my life isn't even trivial compared to a universeal scale i hatte that its called universe its one many
wozzers2 1 year ago
i think i've worked it out the OU is to the whole universe isn't even what the OU is to a quark(smallest known elementary particle) it relatively is smaller i believe the inner frontier will allow us to learn about the outer frontier the OU is basically less than an atom relative to the Universe
wozzers2 1 year ago
Basically he's saying the universe expanded faster then light speed.
Shaunt1 1 year ago
Confuzzled. Does (is) space expand (created) between objects? or is it that it expands from the outer "layers" of the universe, taking the rest of objects with it?
ultimage7 1 year ago
I wonder how many thousands of galaxies leave our visible universe every day. probably millions whole civilisations lost for ever everyday and basically become non-existent to us
spaceghost1313 1 year ago
That's it, I'll be a cosmologist.
n1a1s1i1m 1 year ago 33
is there a mathematical ratio in which space is expanding? like you were saying about the photon taking 13.4 billion years to reach us from 46 billion light years away... what is the ratio?
SaphiraPorter 1 year ago
So this means newer and newer light from that far away object will eventually never reach us? So.. deep space observation should get dimmer and dimmer, until we got all the light we could from that far away object. So the observable universe should be shrinking?? (aside from new emmiting objects).
Thats kinda sad if its true !!! :-(
SSuperCuriouss 1 year ago
so space expands but the matter doesn't?
Kastralis 1 year ago
Goddam, I love this stuff.
Sconz32 1 year ago
You seem to be using "light year" and "year" as if they were the same thing. Eh.
seabm4 1 year ago
@seabm4 He just made a mistake talking fast, he obviously knows the difference having a degree from MIT and all.
metabog 1 year ago 6
if all the space is expanding why does matter not also expand? how about the space between atoms?
captncosmos 1 year ago
@captncosmos intermolecular forces and bonds?
silencedfable 1 year ago
@silencedfable
if the expansion rate of space is increasing then wouldn't the strength of any force holding sub atomic particles together also need to increase at the same rate? (like running on a treadmill) but apparently these forces are constant?
neutronstarx 1 year ago
@neutronstarx This is just a guess because I don't know but I think this might be a good anology / reason. Think of people in a vehicle that's going X meters/second. When you're in the vehicle it doesn't feel like you're moving even though you are. Then I guess the big bang expansion would be like having a car wreck and everyone flying out of the vehicle except not stopping. Some of the stuff flying out could be a massive black hole or it could just be big blocks of atoms.
silencedfable 1 year ago
Sal, clarify it to me please: if the universe is expanding (space in itself), is it expanding faster than speed of light? And why?
smicha7 1 year ago
if space is expanding and light is expanding... then so to is time. So what was initially going to take 10 million years to traverse will still take 10 million years to the photon. But to an outside observer it took 13.7 billion years.
McdonaldSpecial 1 year ago
As @MojjoRising asked, what playlist is this? Looked for it but cant find any?
And great work as always with these videos! All the love to you!
henriksultan 1 year ago
what is a singularity? is it the zero dimension?
PlutonGB 1 year ago
@PlutonGB thats what you get when you divide by zero
DeluxeWarPlaya 1 year ago
Is this topic of videos (Cosmology) in a play-list on the Khan Academy site? If so, what is the play-list called?? Cant seem to find it...
MojjoRising 1 year ago
At 5:48 you state that the photons emited from the period of recombination were done so at microwave wavelengths. This is not correct. The photons energy was much higher when emited, but have been heavily redshifted since, hence they are now in the microwave part of the spectrum.
Neutrinoghost 1 year ago
Oh god ! how can Mr. Khan can understand anything ?
what's next ? string theory videos by Khanacademy ? How can you get interest in all the fields of science.
You are unique!
I do not know how everything remains in your memory(whatever you taught in your videos)?
Good luck cool teacher...!
ScientificBoysClub
(SBC)
scientificboysclub 1 year ago
does the universe expand faster than the speed of light?
karim7ahsan 1 year ago 2
@karim7ahsan Yes, it is believed so.
Neutrinoghost 1 year ago
i<3universe.
Great and simple explanation all can understand.
zbe8 1 year ago
In the beginning, the expansion was actually going slower (current model) so it's "banging" harder each day.
FHomeBrew 1 year ago
How will you prove the 13.7B light year distance? You can use math to finagle it any which way you can (like Clint's chimp), and as one ape to another, "The fool! To think his ape's brain could contain the secrets of the Krell!" Jesus was a Krell!!
Fentro 1 year ago
@Fentro Please read up on this before calling the people who came up with the 13.7 billion year numbers. Your claim is as foolish sounding to people who know what this is about as is the claim that fools think the earth orbits the sun. This is outside your knowledge. Calling astronomers and physicists fools is like calling a mechanic a fool when you know nothing about cars, but he's steadily tuning and fixing yours. Even your knowledge of Jesus is off. Saying to your brother, "thou fool," =fail.
neoaeonian 1 year ago
It's rather ironic we call it the big bang considering Fred Hoyle, an advocate of steady state, named it sheerly due to the inaccuracy and ugliness of the name while he launched a media blitzkrieg against it.
azaz129 1 year ago
Good explanation.
Satak8 1 year ago
If you ain't first, you are last.
orientalgolem 1 year ago