If I have a super large telescope, would I be looking towards the beginning of the universe no matter which direction I point it?


I read that the Hubble telescope could look 13.2 billion years back in time – what would it see if it turned 180 degrees and looked the other way?

In: Other

Everybody is the center of the universe due to how it expands universally. If I were in another galaxy looking somewhere, what I saw would show me as in the center of the universe and what you saw here would show you as in the center of the universe.

There’s a fixed limit to what can be seen by any telescope so if the Hubble points in one direction it’ll see a certain amount of time into the past and if it points in the exact opposite it’ll see the same amount of time in the past.

There is a caveat though due to things like gravitational lensing. If you find such a lens effect, then you can see further away than you normally could and therefore further into the past. This requires a very specific alignment of galaxies and dark matter between you and the object on the other side of it. If you’re referring to this effect as the limit, then the time you can see into the past differs based on how strong the effect is and where it’s located. Different lensing effects magnify what’s behind them differently so you aren’t guaranteed to see the same timeframe into the past with every lensing event found.

‘Back in time’ is not in a physical direction. The Hubble telescope can see things as they were many years ago, because that light has taken a long time to reach us. It would be like if your friend went to a distant city and took a photo and then brought it back to you two weeks later. The city in the photo is how it looked two weeks ago, not how it looks right now.


The universe is expanding in all directions at the same time. To get a sense of what this expansion is like, put 3 marks on a balloon. Then, blow up the balloon. As the ballon is filled, each mark becomes farther away from the other marks.

Yes. You would be. However, you will not be able to see it because of doppler effect. As universe has been expanding at very fast rate, the light that was emitted during big bang has also stretched out. The stretching of light means increasing wavelength in the micrometer range. So the light would be a Microwave.

Since at the beginning the universe was completely concentrated at a single location with very high density, and it expanded in all directions, we see uniform image across all directions.

Sine the waves will be MICROWAVE, distributed uniformly EVERYWHERE throught the COSMOS it is called Cosmic Microwave Background (CMB).

So besides being large, the telescope will also need to be able to detect microwaves.

Because light does not travel instantaneously and has a speed limit (C), no matter which direction you point your telescope, it will always view objects as they were in the past. And the further away you look, the further into the past you are looking.

For instance, when you view the moon at night, you are actually viewing the moon as it was approximately 1.3 seconds in the past. When we view mars through our telescopes or if you spot it in the night sky, we are seeing as it was between a 3-13 minutes in the past, depending on the relative orbits of Earth and Mars. And when viewing the closest star (Proxima Centauri) to our solar system, we are viewing it as it was more than 4 years in the past.

So, you can extrapolate from there, and see, that if you continue to move further away in your observations, you will continuously peer further into the past, irrespective of the direction you are looking.

In fact, if the sun spontaneously exploded or extinguished itself, we wouldn’t even know it happened until 8 minutes after the fact. We would simply look up and see the sun, without noticing any difference whatsoever. Kind of fun.

ELI15: In fact, the latest measurements of the curvature of the universe suggest it is flat (and infinite) and there is no preferential point from which the universe expands. This means the observable universe from earth, the entire universe from our perspective (90+ billion light years diameter, due to inflation), is just one in a likely infinite set of observable universes, all of which, aside from our own, we will never be able to access. And even within our own observable universe, assuming we could travel at light speed, we would still only be able to visit approximately 6% of what we can observe, due to how fast everything is moving away from us.

So here is something that needs to be explained so that you kind of get a better picture of what’s going on. When you use a telescope and look “back in time”, it’s not really looking back in time as people would think. Saying you’re checking out a star 5 billion light years away. What you see in the telescope the light given off is 5 billion years old, as that’s the time it took the light to travel to you. That’s why they say you are looking back 5 billion years.

Something like the Hubble telescope has the ability to look further than your standard telescope. The further you can look the further these objects are away which means the light takes longer to reach you.

There is no need to do a 180 degree turn to see the other way. The telescope orbits the earth going round and round, and it’s always pointing outwards. So it’s constantly working to give us a 360 degree view. Think of it like putting a camcorder on a lazy Susan and then spinning it. You’ll get a view of the room 360 degrees on the axis of the lazy Susan.

So turning the Hubble the other way would pretty much just show us pictures of earth honestly lol.

As far as whats out there? Basically the universe is expanding at a rapid speed. So it’s not like we will ever be able to see the edge of the universe. So whatever we see through the telescope is the light being shot at us from that direction. We have no way of seeing what is past the edge of the universe.


No matter which way you look, you will be looking into the past.

Everything you see in front of you, you see as it was at some point in the past. It takes time for the light from any object to reach your eye.

Say you’re looking at a computer monitor 24 inches in front of you. (using mine as a measure).: The speed of light is ~186,000 miles per second. So it took the light from your monitor ~2 nanoseconds (2 billionths of a second) to reach your eye. You’re seeing it as it was 2 nanoseconds ago.

You see the moon as it was 1.3 seconds ago.

You see the Sun as it was over 8 minutes ago. It could have exploded 4 minutes ago and we will not know it for another 4 minutes.

The further distant an object is, the older the light reaching your eyes from it.


Many people misconstrue the Big Bang and think of space as an empty room and the Big Bang as an explosion that then fills the room.

A better interpretation is that the room itself was very small and then the Big Bang happened and the room has been expanding every since.

So when you take your telescope and look in all directions, you’re seeing different parts of the room. But all parts of the room were once all at the same point at the instant of the Big Bang. So no matter where you’re looking, you’re looking at the Big Bang.

If the Universe is expanding, it means that “stuff” used to be closer, right?

Can I point my super telescope to different locations and see the exactly same objects, but younger? Like, let’s say Galaxy A is on the left and Galaxy B is on the right. If I look into the past deep enough, will I see Galaxy A and B together, either looking at A or B past?

Well, wherever your looking, what you see is from the past no matter what. So yeah, kinda wherever that telescope is pointing is showing you images/data from the past.

Yes, but actually no. The notion that you can somehow step out of spacetime and look at it from an external perspective is incorrect.

Two interesting books about visualizing multi-dimensional physical perspectives are the 1884 tale by schoolmaster Edwin Abbott called “Flatland” (actually a commentary on Victorian social hierarchy) and the 1965 English translation of the 1957 novel by Dionys Burge called “Sphereland”.

An easy analogy is if you were on a boat out at see. You can only see so far out due to the curvature of the Earth. Someone else out in the ocean would have a different horizon since they would only be able to see the same distance around them.

This is also what you can think of for using a telescope. Earth is a boat out in the universes ocean. Every direction you look you can see the same distance away. This isn’t due to curvature like the ocean boat example. Instead it’s due to the speed of light which is a constant. We see the same distance in every direction because it took the light that long to reach us.

Think of yourself on a boat in the middle of ocean. Where is the horizon? That’s how you should think about the edge of the universe where the curvature of the Earth is substituted for the finiteness of the speed of light.

The horizon is equal distance from your “center” such is the universe.

I like to imagine the universe as a balloon. When you blow up the balloon every point on the surface moves apart from each other and there is no uniform center.

Is the expansion of the universe measurable? Is Jupiter or Alpha Centauri going farther and farther away?

Everything you look at is in the past. Everything. The farther away the thing is, the farther back into its past you are seeing. On a global scale, this time differential is minimal, getting larger the farther out you go. The sun you see is from 8 minutes ago. The closest star we can see we are seeing what it was 4 years ago. No matter where you look, you are looking into the past and many of the stars you see are dead and have been for millennia.

Yes! u/brokennoggin has the general idea of the cosmological principle but the example I usually like to give is the expanding balloon analogy. the big bang expanded the universe drastically over time from a small point to essentially and inflated balloon. If you were living on the surface of the balloon, where is the “center”? You could argue that you are the center, you could argue that there is no center, they are both correct. What a telescope does is that it looks “back in time” like you said. Back when the “balloon” wasn’t as large. The bigger the telescope, the further back you can look and the “smaller” the balloon you’re living on appears! After a certain point, the “universe” at a certain point looks so small that no matter which way you’re looking it’s staring at the same object!

It also means there’s a theoretical limit, you cant see “through” the balloon no matter how far back you look, it just gets to the point where it’ll look like that regardless. This would be what the Cosmic Microwave background would be analogous to.