How can we see 46 billion light years in space if Earth is less than 6 billion years old? (please read whole question below)?

Question

If Earth is under 6 billion years old, and we can see 46 billion light years in any direction in space, couldn't we see ourselves, or at least what Earth was before it was Earth?
How can we see 46 billion light years if we are only 5 billion years old? Doesn't that create a paradox?
If a car started at the base of a mountain, and drove forward for 3 light years and then looked back at the mountain, he would be viewing the mountain as it was 3 years ago, and would see his own car there at the base?
I understand that I must be missing something.
I just don't understand how we can see almost 10 times further than the age of our own planet. 46 billion years ago the Earth didn't even exist, and the universe looked very different. 

Answer 1

Do you mean that I cannot see the pyramids because I was born after they were completed?



1. We cannot see 46 billion light-years in space. When calculating distances that we can see, we use "look-back" distance:  if the light took a million years to get here, then that object is a million light-years away. Astronomers calculate distances and positions based on what we see now.



If a star blows up now, even if that start is a thousand light-years away, we call it "Supernova 2020" and not SN1020, even though we know it blew up a thousand years ago, and the light of the explosion took a thousand years to get here.



The position of the star would be given as its position where we see it now. We do not try to guess where it would have been a thousand years after the explosion in 1020.



In this scale of measurement, we can "see" as far as (roughly) 13,800,000,000 light-years (13.8 milliard in long scale unit names, 13.8 billion in short-scale unit names).



And what we do see at that distance (the Cosmic Microwave Background radiation), we see it as it was 13.8 billion years ago... with the redshift each photon had to endure during its 13.8 billion years of travel from "there" to here.



2. Cosmologists try to understand the universe, as a structure, the way it would appear to us IF (a big if) we were able to see all of it as it is NOW. This means that whatever we (astronomers) see at 5 billion light-years - where it was 5 billion years ago - they (cosmologists) place it where it would be NOW, considering all the expansion of space that has taken place during these 5 billion years.

For them, this thing is NOW located at (let's say) 10 billion light-years. However, they do not SEE it at 10 billion light-years. Whatever light this object is emitting NOW will take 10 billion years to get here.

The distance used by cosmologists is called the co-moving distance. It is the distance where things would be NOW, if we could see them where they are NOW (that is, if the speed of light was infinite).



The CMB radiation appears to be 13.8 billion light-years away in look-back distance. Back then, it was just a general glow (orange in color) that was simply caused by the temperature of the (mostly) hydrogen gas taking up the volume of space. Around 3000 K.

If you were to magically see what that looks like NOW, you would NOT see this hot gas. You would see whatever that region of space has become over 13.8 billion years: galaxies, stars, planet...

And, because space everywhere has been expanding during all that time, these objects would NOW be a little over 40 billion light-years away from us (co-moving distance). But there is no way anyone sees any of these objects at 40 billion light-years. All we see is the "glow" of that region as it was 13.8 billion years ago, when its distance from us was 13.8 billion light-years.



3. Roughly 8 to 10 billion years ago, within our already existing Galaxy, there were gimongous clouds of gas (mostly hydrogen, some helium) and "dust" (anything else blown out into space by exploding supernovas of earlier stars). Many of these clouds collapsed under their own gravity and caused mass to accumulate in pockets.



One pocket in one cloud became crowded enough to have a very high pressure (caused by gravity) at its centre. The pressure and temperature were sufficient to trigger hydrogen fusion in the central object: our Sun. Around the Sun, the rest of the matter assembled itself, more or less at random, into planets. That is where our Earth was 4.5 billion years ago. 



Since the formation of Earth, our Solar system has gone around the Galaxy approximately 20 times, orbiting at approximately 230 km/s relative to the Galactic centre.



To make things even omore complicated, our Galaxy itself is moving, relative to the Virgo Supercluster (itself moving...).  Relative to the CMB radiation, our Galaxy is moving at close to 400 km/s

Answer 2

46 billion years?  Wow, what a claim.  We can see about 13 billion years, and the radiation is rather easy to find...

Answer 3

We can't. We can detect objects up to about thirteen thousand million light years away, which is the approximate age of the Universe, but that's coincidental. The light which reaches us from them started out at a time when they were closer. It isn't necessary for the Earth to have existed at that time for this to be possible.

Answer 4

nobody can see whats 1 year in earth space or whatever you want to call it.



for instance, if something is measured in the time it takes to reach it, thats like me saying I am 20 years away from that little male baby that will need 20 years to grow up before it can sit down and talk about naked women and boobies with me.



do you see what i mean ?

Answer 5

Because the light from those distant galaxies was already traveling through space long before Earth existed.

Answer 6

Why do you assume the Earth was created right at the beginning of the universe?  It wasn't.  Of course we can see things that are older than the Earth.  Just like you can see antiques that were made before you were born.

Answer 7

the light we are and have been receiving is  12-13,000,000,000 years old,the distance limitations owe to gas and innumerable clumps  huuuge clumps of galaxies, glare from massive and old suns out there,floating bodies, until we launch rockets with vastly more powerful light gathering lenses,launching them far enough out where the beyond is much less crowded with gas clouds,we are at a roadblock  in seeing the edge or beyond the edge of creation

Answer 8

Light

And it travels at 186, 000 Miles per Second

A light year is the distance Light has travelled in a year

An object One Light Year away, we can see as it was one year ago

46 Billion Light Years away is also the time ago that the light left it

We are here on Earth, Base if you like and we can see as far in every direction as long as the Object is Bright enough

For what is not Bright enough, could it be Dark Matter ?

Something I would like to add

HD140283 is pretty standard apparent Magnetude 7. 205

A Metal Poor and Oxygen rich Subgiant star with a Rapid real movement of 800, 000 mph or how about 1.3 Million Km/ hr

In respect to earth though that is the width of the moon In 1, 500 years

 It has been studied for 100 years now

A Type 2 Star where our Sun is a Type 3

Type One Stars were the first to ignite from the Cosmic Soup

 Its given age  is 14 Billion years

Nicknamed Methusila it has a Highly Eliptical Orbit

from the outside edge of the Milky Way to across the Galactic Arms

180 Light Years away from 200 light years in less than one year

Say there was an Earth like Planet orbiting in its Goldilocks Zone, and why not

How much of an Evolution could it have by now and it is coming this way

Answer 9

We're not looking back in time, we're looking at light emitted from sources that are 46 billion light years away. This means that the light was EMITTED 46 billion years ago, 40+ billion years prior to our planet forming. We're not looking at our own planet as it was billions of years ago, we're seeing light from a source that most likely no longer exists. It took that light 46 billion years to cross the 46 billion light year distance. Understand?



So you're asking where the Earth was, 5 billion years ago relative to an object 5 billion light years distant?? Assuming that was after the earth formed, the Earth was right here in orbit around our sun. 

Answer 10

Under your feet, the Earth is still there, not out in space.

You are confusing the starlight coming from the great distances beyond our galaxy, billions of lightyears, with the age of Earth, measured in years.

The word "years" is used in both, but have nothing to do with each other.

Lightyears is a distance measurement.  One lightyear is almost 6 trillion miles long.  4.3 of them is distance from Sun to Proxima Centauri, closest planet outside the solar system.  Years by itself is a time measurement.  One year is how much time passed in months, weeks, days, hours, minutes, seconds to travel once around our sun.

If there was a giant mirror in space, covering a huge area, and was 2.5 billion lightyears away, you could look at the bounced image of Earth just being formed.

The round trip of light from earth from 5 billion years ago would be reaching you just now.

Light from farther away than 5 billion lightyears is reaching you just now.  That light left the source, stars in other galaxies, way before Earth formed.

Answer 11

It isn't a paradox, we cannot travel faster than the speed of light so we (the earth) are always "in sync" with the light from our own planet.



The only time you would be able to see yourself in the past is if you could travel faster than light, say by teleporting to another planet instantaneously. If you were to travel 3 LY away then in three years look back at earth with a REALLY  good telescope that could see the surface the you could actually watch yourself leaving the planet as it would take that long for the light that bounced off you three years ago to catch up with your new position in the universe.



The universe we see is actually not a realtime image for this resson, the closest star beyond our solar system is about 4 LY away so we see it on a 4 year delay and the outer edge of the universe is on a 13.8 billion year delay (as for how it is further than that in actual LY you will have to ask a real astrophysicist... expansion of spacetime is above my paygrade)

Answer 12

If you are actually interested in learning about it - you can start here:



https://medium.com/starts-with-a-bang/if-the-universe-is-13-8-billion-years-old-how-can-we-see-46-billion-light-years-away-db45212a1cd3

Answer 13

Stand on a mountain with a telescope and you can see for miles but why would you be able to observe yourself?

Answer 14

The earth did not exist how ever the light was travelling towards where earth will be in 5 billion years time.

Answer 15

Just a minute?  



You have some interesting concepts there but your language and use of wording is all mixed up.



I'll take your question to Joe Biden and see if I can get him to translate for you.    

Answer 16

I don't see why there's a problem. We should be able to observe things that are older than the Earth. The age of the Earth makes no difference because the universe itself is older than the Earth, and the light that we would be seeing could have been here before the Earth existed.

Unless the universe forms a loop, the light that the Earth emits is not likely to come back to us. Some other celestial body, maybe an alien, will be observing it, not us.

Answer 17

The light headed our way didn't care whether we were ready for it or not.  In essence, it started without us.

Answer 18

You're overthinking it.  A year is a unit of time, a light year is a unit of distance.

Answer 19

If we knew all you'd be correct on both counts.



But as we know now we cannot see 46 billion light years unless the earth is as old.



But like the creationists the science have their godlike geniuses too that know all and created the universe.



But the main thing to remember is the earth is estimated to be as old as it is. No one really knows.

Answer 20

The whole "seeing 46 billion lightyears" is something of a fake.  What is really meant by that is that material we currently see as it was 13.7 billion years ago --- that is, emerging from Big Bang as hot plasma (we see it as the Cosmic Microwave Background) --- is NOW 46 billion lightyears away, having moved away with the expansion of the Universe, and (presumably) as evolved as we are into galaxies, stars, and planets.



In truth, we cannot "see" more than 13.7 billion lightyears away, because those photons were released shortly after the Big Bang and have been travelling in our direction ever since.  Meanwhile, the Solar System developed and we were eventually born, and the matter that emitted those photons has moved beyond our event horizon, and formed galaxies, stars, and planets out there.



If there were a giant mirror 2.5 billion lightyears away, and we looked in that mirror, we would see the Earth forming.  If we look 5 billion lightyears away, we see conditions that are statistically similar to the conditions that formed the Earth 5 billion years ago.

Answer 21

The planet Earth is 4.5 billion years old.

The sun is 5 billion years old.

The Milky Way galaxy is 13.6 billion years old.

The universe is 13.8 billion years old.



The observable universe is a sphere that is 93 billion lightyears in diameter,

which means that we can see out to half that distance or 46.5 billion lightyears.

Since, as far as we know, nothing in this universe can travel faster than the speed

of light and the universe is only 13.8 billion years old, there appears to be a

paradox. The apparent paradox is resolved when we realize that, during the

universe's inflation era, space-time itself was expanding at faster than lightspeed.

While nothing within the universe can move faster than light, the universe itself can

and did expand faster than light. In fact, the universe might soon (in cosmological

terms) be entering another inflationary period, since it has been recently discovered

that the universe's expansion rate seems to be increasing.

Answer 22

Light years are units of distance - itdoesn't matter where you were when the light set out, it doesn't matter if you even existed, you just have to be somewhere to see that light.



46 billion light years makes things interesting because the universe is about 13.8 billion years old - it shouldn't be possible to see anything further away than 13.8 billion light years, should it?  Your example shows we can, and part ofthe reason is that the universe is still expanding.  The link has a better explanation than I can provide.

https://www.forbes.com/sites/startswithabang/2020/01/25/ask-ethan-how-can-we-see-46-1-billion-light-years-away-in-a-13-8-billion-year-old-universe/

Answer 23

If you were to look from Earth, 5 billion light years into space, then you'd see space, not Earth, because you're already on Earth!



You don't think very clearly!

Answer 24

The universe is older



THE EARTH  did not just POOF into existance when the  universe started 



assuming we had a big bang   the  explosion would have created many suns  before our sun was created ..



that means it was many years after the   universe started to expand  that the earth was created 



NO PARADOX ..  



you think you are  being complicated you are not



there is also  a  good  science video on the expansion of the universe  and   how  it expands at a certain rate and what light we see

Answer 25

You not actually looking that far into space.  What your seeing is LIGHT that has come that distance.   That Photon of Light left it's Source 46 Billion years Ago and traveled through space and is just now pinging on your eyeball.

When you look at the Sun, Your seeing it's light that left 8 Minutes Ago, not the actual Sun.

Answer 26

The Universe is older than the Earth.





Duh.

Answer 27

>>How can we see 46 billion light years in space if 

>>Earth is less than 6 billion years old? (please read 

>>whole question below)?

>>If Earth is under 6 billion years old, and we 

>>can see 46 billion light years in any direction 

>>in space, couldn't we see ourselves, or at least 

>>what Earth was before it was Earth? 

Light moves in more or less straight lines... Our age doesn't matter - the light coming to Earth came from elsewhere - and we wouldn't be seeing our planet at all. 



>>How can we see 46 billion light years if we are only 

>>5 billion years old?

Think of it this way... A quarterback throws a pass.  The receiver had to block two players, run a fake to the left, then bolt downfield to catch the pass that was already thrown - when he arrives at the right spot, he catches that football. 

Similarly, the light we're seeing from such a long distance away began it's journey long before Earth formed. Generations of humans grew, aged, and died - until finally the light we're seeing today just arrived... Earth didn't have to exist for that light to begin it's journey. 

>>Doesn't that create a paradox? 

No, not at all...



>>If a car started at the base of a mountain, and drove 

>>forward for 3 light years and then looked back at the

>>mountain, he would be viewing the mountain as it 

>>was 3 years ago, and would see his own car there 

>>at the base? 

So, lets  look at this two ways... first - he drives away from the mountain.  This is very similar to the Voyager craft leaving the solar system.  The car you're in is moving much slower than the speed of light... yes, the image you're seeing as you get further is getting older - but, **its never older than when you left.** So - whenever you look back at the mountain - the light you're seeing is always newer than the time you left. 



But... try THIS:

You don't drive your car 3 light years away - you use a transporter in Star Trek to simply *beam* yourself 3 light years away instantly....  NOW, when you look back at the mountain, the image you're seeing is from 3 years ago, before you even got there.  For the next 3 years, you could watch yourself show up, get prepared for your trip - and finally leave, only to then see yourself dematerialize when you beamed to where you are. 



>>I understand that I must be missing something. 

I hope I'm filling you in understandably...



>>I just don't understand how we can see almost 10 

>>times further than the age of our own planet. 

It's because the light we're seeing left long before our planet formed, and it's just now arriving from very far away. 



>>46 billion years ago the Earth didn't even exist, and 

>>the universe looked very different.  

True... the Universe is thought to be about 13.8 billion years old - but, there's a characteristic of expansion - which means it continues to expand as time goes on... (It's another can of worms...) 



>>Updated 12 mins ago: 

>>What I'm really asking is if we were to look 5 billion 

>>light years in space, where is the Earth relative to 

>>what we are seeing? 

Within that 5 billion light year radius, the light we're seeing from all the objects within is *newer* than 5 billion years ago. Our solar system formed from a great cloud of gas - and, from 5 billion light years *from here* - some alien could look through their telescope and see the light from that nebula as it was.  But - for us, here - the light has left; it's gone out to the universe... When we look at our own solar system, we can only see the light that's a few minutes to a few hours old...

Answer 28

I'm not a cosmologist, astronomer, nor astrophysicist but am educated in many ways. Let's start with a few thoughts and see it's enough. 



I can hold things today that were produced before I was born. The 10,000 year old ice I touched in a visit to Alaska was here before I could conceptualize "me" back hundreds of generations. I trust the science of the dating and do understand nuclear science and carbon dating and stratification and can get their science of date estimations. Just because I wasn't here, doesn't mean nothing existed. 

We know everything is in motion. Certainly we move across a room or drive a car. The Earth rotates and makes a path around the Sun. Our solar system moves around our galaxy the Milky Way, and galaxies hurl out from a central point we theorize as a Big Bang. When we look at the Sun we know that light left the Sun about 8 and a half minutes ago (varying) and it isn't exactly where we see it now. The Sun and Earth are both in motion and we see from our position what was 8 or 9 minutes ago. 



Under the same principles, the stars are not now where we see them. Adding in the first, I don't have to be in existence when something is created. It still was created, even without my presence. Therefore, if the distance is even 10 billion light years, that star or thing was there 10 billion years ago and whether I, the Earth, or anything else existed does not say that thing did not exist.



I will state I am a Free Thinking Atheist, accepting there could be a universal consciousness, life forces, physical things beyond our current measuring, but cannot envision an entity Creator of the major religions. I state honestly that we do not know the origin of life, the beginning of the universe or what happens after death, and would rather admit a lack of knowledge than fill it in with a timeless entity. 



I don't know whether a 46 billion number is accurate. It doesn't bother me. But, I do accept that things could exist somewhere before Earth, because I know the principles and logic presented here.  Good enough? If not, I may need a few extra years of school in the fields of cosmology and physics related.

Answer 29

The earth didn't exist, but the source of light, however many light-years away, did. So that's why we can see it. It doesn't matter how you g or old the earth is. Light that wanders our way from anywhere can be observed. And that light provides a static view (at any given instance) of whatever and whenever it came from.



The earth is very young in astronomical terms. Many celestial object were emitting light way before the earth existed. Some objects we can observe are so far away and so old they don't exist now. 

Answer 30

Earth is not the universe.

https://www.forbes.com/sites/startswithabang/2019/02/26/how-did-the-universe-expand-to-46-billion-light-years-in-just-13-8-billion-years/

Answer 31

It takes 8 minutes for light from the sun to reach us yet a new born baby can still see the sun.

Answer 32

No. It does not create a paradox. You are missing several points. The Universe was created 13.8 billion years ago, give or take tens of billions of years either way. The Sun and Solar System didn't form until 4. 65 billion years ago. That means neither the Sun nor Earth existed for 13.8 billion - 4.65 billion years = 9.15 billion years while the Universe was expanding. I need to double check that math because I did that in my head without calculator.



The other points you are missing is that right after the the Big Bang the laws of physics as we currently understand them did NOT exist during the Planck epoch and the Universe hyperinflated MUCH faster than the speed of light in a vacuum because there was NO. vacuum and no matter and no light. The Universe was ALL energy. The fundamental forces of the Universe took 380,000 years to separate from each other. The exact order the fundamental forces split apart and the number of fundamental forces is still being debated.



A light