If Our Galaxy Was The Size Of A Dinner Plate

[Mintaka]

how far away would the 'edge ' of the visible known universe be?

[CraigD]

If Our Galaxy Was The Size Of A Dinner Plate ... how far away would the 'edge ' of the visible known universe be?

Let's see ... The visible universe has a diameter of about 28,000,000,000 lightyears, the Milky Way galaxy about 50,000, so if a typical plate has a radius of about half a foot (15 cm), then the edge of the visible universe is about 53 miles (85 km) away.

 

Pretty cool question and visualization. :thumbs_up

[Mintaka]

Let's see ... The visible universe has a diameter of about 28,000,000,000 lightyears, the Milky Way galaxy about 50,000, so if a typical plate has a radius of about half a foot (15 cm), then the edge of the visible universe is about 53 miles (85 km) away.

 

Pretty cool question and visualization. :thumbs_up

 

Thanks, but now I'm a bit confused. Does that assume we are in the middle of the universe?

[Mintaka]

Thanks, but now I'm a bit confused. Does that assume we are in the middle of the universe?

 

And, is it possible that the universe is actually much bigger than the 'visible' part we can detect? Isn't it possible it goes on much further but our telescopes can't detect it?

 

What if I said the universe was in fact 980 trillion light years in diameter? Could I be right? If not, why not? B)

[sanctus]

I think it is right to say that we are in the middle of the VISIBLE universe...but note the emphasis on visible, it does not put as in any special place in whole universe.

[Mintaka]

Thank You Sanctus,

 

I found this, please cast a glance at it -

 

A penny is about 1 inch across. If this equals 100,000 light years as the diameter of the Milky Way, the Andromeda Galaxy is about 23 inches away, the Virgo Cluster of Galaxies is about 60 million light years or 600 inches away, and the nearest quasar, 3C273 is about 1.5 billion light years or 150,000 inches or a bit over 2 miles away.

 

The visible universe has a horizon at about 14 billion light years and the most distant galaxies seen by the Hubble Space Telescope are nearly at this limit at about 12-13 billion light years. This is about 15 - 20 miles away from the Milky Way 'penny' and is the farthest we can ever see. Because our best model for the universe consistent with data is that it is infinite, then of course there is much more space even at the scale of our penny! In our scale model, though our horizon is at 20 miles from us, the rest of the currently unobservable universe stretches thousands or even millions of miles beyond the last 'penny' we can see. As the universe gets older, these more distant pennies will come into view, but of course we will see them as they were when they were much younger that the actually are.

 

 

 

 

I don't understand , can someone clarify please? This scientist is saying that the distance Hubble can see to is about 12 - 13 billion light years, and that the visible universe has a 'horizon' of about 14 billion light years. I presume this is because the Big Bang is supposed to have happened 14 billion years ago, so that is the 'limit'. So....why does he say " of course there is much more space..."...and .." the rest of the currently unobservable universe stretches thousands or even millions of miles beyond the last 'penny' we can see? Does this mean in fact that the universe is actually much bigger than the 14-billion light years usually quoted?

 

 

[sanctus]

I wanted to write myself something which is written way clearer on this wiki-link :-).

 

Mainly the introduction should clear everything.

Feel free to ask for clarifications...if I can answer them :-)

[Deepwater6]

This confuses me a bit. From the WIKI-LINK it almost sounds like the universe goes way beyond 13-14 B yrs. but the light has not had time to make it here yet. Is that a correct statement? If so do we gain more time (observable universe) as everyday goes by? Albeit slow due to the scale. I heard something on a program the other day that we have have only observed 3% of the universe. Did they mean mapping or seeing? How do we know what is there if we can't see it?

[CraigD]

This scientist is saying that the distance Hubble can see to is about 12 - 13 billion light years, and that the visible universe has a 'horizon' of about 14 billion light years. I presume this is because the Big Bang is supposed to have happened 14 billion years ago, so that is the 'limit'.

You assume essentially correct. Since best theory states the big bang happened about 13,750,000,000 years, and light travels 1 light year per year, and no signal travels faster than light, light or any other signal from any object more distant than about 13,750,000,000 light years has not had enough time to get to us, so we can’t detect – “see” – any such body.

 

It’s a bit more complicated than that, but this is the basic idea of a “visible universe horizon”.

 

So....why does he say " of course there is much more space..."...and .." the rest of the currently unobservable universe stretches thousands or even millions of miles beyond the last 'penny' we can see? Does this mean in fact that the universe is actually much bigger than the 14-billion light years usually quoted?

You can imagine the “greater” universe to be much bigger than our observable one, even infinite, but this is purely an exercise in imagination, as we can’t possibly detect anything beyond the visible universe horizon.

 

As time goes on, this horizon enlarges, so if there is something “out there” – another big bang event, for example, we might at any time begin detecting it, as light from it arrived. I believe this is what Sten Oswald means in this webpage (which appears to be the one you quote, Mintaka) when he says “As the universe gets older, these more distant pennies will come into view ...” Although Oswald is a better educated astronomer and cosmologist than I, I think he fails to incorporate the current consensus of cosmologists in the understanding he used when writing this page.

 

Currently, to explain various large and small-scale features of the observable universe, it’s necessary to conclude that the universe expanded suddenly, and is continuing to expand at an increasing rate. For this reason – the “more complicated” reason I allude to above – the distance that would be measured is somehow, supernaturally, you could instantly measure the distance to the most distant observed objects, you’d find it is further than the light could have traveled in the time it has existed. This is because the earlier parts of the light’s trip took place when the universe was smaller than it is now.

 

If this apparent increase in rate of expansion of the universe continues, rather than bodies not yet visible becoming visible as Oswald predicts, objects that are currently visible will become invisible, as the space between them and us eventually increase faster than light can cross it. If this is the case (we really don’t, IMHO, understand the underlying physics of cosmic expansion well enough yet to say with confidence that it is), as time goes on, the visible universe may become smaller and smaller, until eventually we are unable to see any galaxies outside our own, and eventually, all the stars in our own galaxy – if this “big blackout” occurs before all the hydrogen and other fusion-able elements needed for stars to make light is consumed. Even if it doesn’t, there may be light and other radiation sources, such as matter-destroying and evaporating black holes.

 

this webpage is one of many explaining what I summarize above in more detail.

[Racoon]

So we reach the same unconfirmed conclusion...

We know the Universe is expanding. (like dots on a balloon when you inflate it)

 

But the real question is.. What does the Universe keep expanding INTO??

If I take my Galaxy and expand it, it has to go somewhere else in adition to what it already occupies...

 

Its like Zen Buddhism, its the Emptiness that creates usefulness, like the hollow of a cup.

 

Is what the universe expanding into, usefull emptiness?? What is the emptiness? How vast does it encompass?

 

Its beyond our brains and computing power at this point :o

[Mintaka]

Racoon

 

this is the same problem i have with the big bang theory - haha.....what was there for these initial exploding particles to 'expand ' into? :rolleyes:

 

what was there 'before' they formed?

 

How can a 'point' in time be called a 'beginning' without the possibility of imagining a 'point' in time before that beginning?

 

The idea of infinity is impossible for our minds to grasp, but unfortunately, it also seems impossible for us to be comfortable with the idea that something can 'start' without there being something before it, and 'end' without there being something 'after' it.

 

:D

 

 

 

So we reach the same unconfirmed conclusion...

We know the Universe is expanding. (like dots on a balloon when you inflate it)

 

But the real question is.. What does the Universe keep expanding INTO??

If I take my Galaxy and expand it, it has to go somewhere else in adition to what it already occupies...

 

Its like Zen Buddhism, its the Emptiness that creates usefulness, like the hollow of a cup.

 

Is what the universe expanding into, usefull emptiness?? What is the emptiness? How vast does it encompass?

 

Its beyond our brains and computing power at this point :o

[Mintaka]

someone in here used the birth of a baby as an example of 'something from nothing', but that seems a bit misleading to me as we know how babies are made and where they come from. :)

 

 

 

Racoon

 

this is the same problem i have with the big bang theory - haha.....what was there for these initial exploding particles to 'expand ' into? :rolleyes:

 

what was there 'before' they formed?

 

How can a 'point' in time be called a 'beginning' without the possibility of imagining a 'point' in time before that beginning?

 

The idea of infinity is impossible for our minds to grasp, but unfortunately, it also seems impossible for us to be comfortable with the idea that something can 'start' without there being something before it, and 'end' without there being something 'after' it.

 

:D

 

 

 

 

[CraigD]

…

But the real question is.. What does the Universe keep expanding INTO??

If I take my Galaxy and expand it, it has to go somewhere else in adition to what it already occupies...

If my hunch about the ultimately correct theory of physics is right, it’s what’s ultimately real is only the relationship of particles (whether those of the Standard Model, or some better successor theory, I’ve no confident guess). In this view, space is an emergent property of these complex relationships, so the question of “what is the expanding cloud of baryonic matter called the universe expanding into” is the wrong question to ask. What we should be asking is the terribly complicated “what is this ultimate particle relationship theory”.

 

That said, if my favorite “what was there before the Big Bang” theory is correct – that there was the usual sea of virtual particles, which, given enough time, randomly undergoes a large scale fluctuation – then the “out there” beyond where from any light could yet have reached us should be as virtual particle-rich as our neighborhood before the big bang, or maybe moreso (I’m vague on how particle physics and the metric expansion of space, AKA cosmic inflation, relate), and it was only chance – though vastly likely chance – that we aren’t today observing a very isotropic sky with a clear nearby “other big bang” in it.

 

Is what the universe expanding into, usefull emptiness?? What is the emptiness? How vast does it encompass?

This gets into the esoteric realm of the large scale topology of space (which it’s no less meaningful to talk under my assumption that space an emergent property of some ultimate underlying nature of particle physics). In short, though, everything I understand leads to 2 possible conclusions:

• It’s “flat” (a catchall that I take to include hyperbolic and other not strictly Euclidean but not spherical topologies), in which case, absent any ultimate theory explanation otherwise, it’s infinite in extent
  
• it’s spherical (in more than 3 dimensions, AKA a hypersphere). Look or travel far enough in one direction, and you see/arrive back where you started.
  

If the universe is spherical, it must be very big, as we don’t see obviously the same nearby galaxies in one direction as we do in the opposite. There’s a community of astronomers searching the sky with ‘scopes and statistics to detect if the universe is spherical and not so small that this isn’t the case for very distant galaxies.

[Mintaka]

If my hunch about the ultimately correct theory of physics is right, it’s what’s ultimately real is only the relationship of particles (whether those of the Standard Model, or some better successor theory, I’ve no confident guess). In this view, space is an emergent property of these complex relationships, so the question of “what is the expanding cloud of baryonic matter called the universe expanding into” is the wrong question to ask. What we should be asking is the terribly complicated “what is this ultimate particle relationship theory”.

 

That said, if my favorite “what was there before the Big Bang” theory is correct – that there was the usual sea of virtual particles, which, given enough time, randomly undergoes a large scale fluctuation – then the “out there” beyond where from any light could yet have reached us should be as virtual particle-rich as our neighborhood before the big bang, or maybe moreso (I’m vague on how particle physics and the metric expansion of space, AKA cosmic inflation, relate), and it was only chance – though vastly likely chance – that we aren’t today observing a very isotropic sky with a clear nearby “other big bang” in it.

 

 

This gets into the esoteric realm of the large scale topology of space (which it’s no less meaningful to talk under my assumption that space an emergent property of some ultimate underlying nature of particle physics). In short, though, everything I understand leads to 2 possible conclusions:

• It’s “flat” (a catchall that I take to include hyperbolic and other not strictly Euclidean but not spherical topologies), in which case, absent any ultimate theory explanation otherwise, it’s infinite in extent
• it’s spherical (in more than 3 dimensions, AKA a hypersphere). Look or travel far enough in one direction, and you see/arrive back where you started.

If the universe is spherical, it must be very big, as we don’t see obviously the same nearby galaxies in one direction as we do in the opposite. There’s a community of astronomers searching the sky with ‘scopes and statistics to detect if the universe is spherical and not so small that this isn’t the case for very distant galaxies.

 

 

 

 

Craig, what are 'virtual particles'?

 

How is possible for virtual to become real?

[viddirector]

how far away would the 'edge ' of the visible known universe be?

 

It might BE the size of a dinner plate and we might be microscopic. The better question is do we really have anyway of knowing?

[JMJones0424]

It might BE the size of a dinner plate and we might be microscopic. The better question is do we really have anyway of knowing?

 

That's a pretty rediculous statement. The diameter of a dinner plate can be measured to be about the distance light travels in 10^-9 seconds, and the diameter of the visible universe is about the distance light travels in 28 billion years. How could one seriously claim those two measurements are equivalent?