Size of Earth vs. Size of universe: A good analogy

What do you mean by size of the universe?

The universe is infinite. It never ends.

Ph.D in Astronomy. wrote:

What do you mean by size of the universe?

The universe is infinite. It never ends.

Au Contraire Mon Frere

Ph.D in Astronomy. wrote:

What do you mean by size of the universe?

The universe is infinite. It never ends.

There's no edge, but there is a finite volume.

someone had to do it wrote:

What happens when you read the end of the universe? Is it like hitting a wall? That is an odd concept to think about. But of course, the universe is expanding too. Which makes it even weirder to ponder.

There is no end. What happens when you keep walking north past the north pole?

Jeff Wigand wrote:

There is no end. What happens when you keep walking north past the north pole?

ice bath

There's no physcial edge to anything from the perspective of someone living on a sphere (e.g., earth). However, it is appropriate to say that there is an "observable" edge to the universe and earth (e.g., horizon).

Curiously, there is a force at work beyond the "observable" edge of our universe which is causing galaxies to migrate together- otherwise known as the dark flow. Scientists believe that a neighboring universe is causing this migration.

everyone trolled softly, great job.

Jeff Wigand wrote:

There is no end. What happens when you keep walking north past the north pole?

Not possible.

hello friends of running wrote:

We know, obviously, that the Earth is quite small in comparison with the size of the universe. Here is the best analogy I've come across.

Imagine you give a baseball to a five year old and ask him to throw it as far as he can. Say it goes 30 feet. Now, ask the best pitcher in the MLB to throw a ball as far as he can. Roughly the distance between the two can decently represent the difference between the Earth and the universe.

I did some math for our friend here.

The earth is has a diameter of about 12,756km, which is equal to 0.000000001348 light years.

The observable Universe (the part that we can see) has an approximate diameter of 93 billion light years, meaning that the portion of the Universe that we can see is about 6,896,989,700,000,000,000 times larger than the earth.

boomgoestheD wrote:

No that's actually a pretty good ratio. Maybe you just don't understand proportions. Ever heard of physics?

How far are you assuming this MLB pitcher can throw?

Jeff Wigand wrote:

I did some math for our friend here.

The earth is has a diameter of about 12,756km, which is equal to 0.000000001348 light years.

The observable Universe (the part that we can see) has an approximate diameter of 93 billion light years, meaning that the portion of the Universe that we can see is about 6,896,989,700,000,000,000 times larger than the earth.

Which means the best pitcher in the MLB (either David Price or R.A. Dickey) can throw a baseball 206,909,691,000,000,000,000 feet (39,187,441,477,272,727 miles, or about 1 billion times the distance from Earth to Mars when the two planets are at their closest).

Here is a good visual

http://www.youtube.com/watch?v=LpChZxPfa-c

Jeff Wigand wrote:

I did some math for our friend here.

The earth is has a diameter of about 12,756km, which is equal to 0.000000001348 light years.

The observable Universe (the part that we can see) has an approximate diameter of 93 billion light years, meaning that the portion of the Universe that we can see is about 6,896,989,700,000,000,000 times larger than the earth.

I repeat, how is this possible? Can someone explain this? If the universe is only 13 or so billion years old how did parts of it get 93 billion light years away from other parts? And how is the light of something 47 billion light years away from us reaching the earth at this time?

Thanks.

Hats too bee axed wrote:

Jeff Wigand wrote:

I did some math for our friend here.

The earth is has a diameter of about 12,756km, which is equal to 0.000000001348 light years.

The observable Universe (the part that we can see) has an approximate diameter of 93 billion light years, meaning that the portion of the Universe that we can see is about 6,896,989,700,000,000,000 times larger than the earth.

I repeat, how is this possible? Can someone explain this? If the universe is only 13 or so billion years old how did parts of it get 93 billion light years away from other parts? And how is the light of something 47 billion light years away from us reaching the earth at this time?

Thanks.

Your problem is that you think that things can only move at the speed of light and no faster. At least that's what I'm guessing your problem is.

The universe is expanding faster than the speed of light. For example, say two objects are moving away from each other each going 5 miles per hour. After 1 hr their separation will be 10 miles not 5. The universe sort of does this but also moves faster than light.

I study outer space, and I think you're spot on.

Here is an applet done amazingly well that you can explore the scale of pretty much everything.

http://htwins.net/scale2/

Hats too bee axed wrote:

Jeff Wigand wrote:

I did some math for our friend here.

The earth is has a diameter of about 12,756km, which is equal to 0.000000001348 light years.

The observable Universe (the part that we can see) has an approximate diameter of 93 billion light years, meaning that the portion of the Universe that we can see is about 6,896,989,700,000,000,000 times larger than the earth.

I repeat, how is this possible? Can someone explain this? If the universe is only 13 or so billion years old how did parts of it get 93 billion light years away from other parts? And how is the light of something 47 billion light years away from us reaching the earth at this time?

Thanks.

"According to general relativity, space can expand faster than the speed of light, although we can view only a small portion of the universe due to the limitation imposed by light speed."

Hats too bee axed wrote:

I repeat, how is this possible? Can someone explain this? If the universe is only 13 or so billion years old how did parts of it get 93 billion light years away from other parts? And how is the light of something 47 billion light years away from us reaching the earth at this time?

Thanks.

Cosmic inflation. The theory that the universe expanded extra fast for the first split second or so. )I'm not sure how this interacts with the speed of light - perhaps it was also faster during the inflationary epoch)

The current answer to why the Universe is much bigger than the 28(or so)Billion light years across indicated by extrapolating out the origin at the speed of light for 13.7Billion years is as follows.

Until an instant after the big bang occurred the laws of physics where not as we measure them now. Space underwent a process called inflation that projected its size to approximately 90% of its currently diameter in far less than one second. Since this point in time (T + 1sec) the Universe is hurtling apart at an average velocity close to the speed of light - and yet its size has still only grown 10% in almost 13.7 Billion years.

Here is Brian Green putting it much more elegantly than I

http://www.youtube.com/watch?v=fJqpNudIss4