Observable Universe
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So, the next question is, can we observe the edge of the universe?
If we were outside of our universe, in empty space, could we observe it?
If we were outside of our universe, in empty space, could we observe it?
JHZR2
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What's to say there is such a thing as empty space?
I've always liked the bubble bath analogy. That is, the "universe" we know and love, is but one bubble, surrounded by other bubbles, which are themselves surrounded by a great many bubbles.
What I want to see, is the bathtub... and what's outside the bathtub...and the bathroom...and the house, etc, etc.
What I want to see, is the bathtub... and what's outside the bathtub...and the bathroom...and the house, etc, etc.
If you want to have some fun looking at the size of everything, check out this interactive model that was made: http://workshop.chromeexperiments.com/stars/ It allows you to zoom into Earth and back out of there to see how close we are to our neighbors in the Milky Way.
Also, there's some fun information on the wikipedia page on the observable universe.
http://en.wikipedia.org/wiki/Observable_universe#The_universe_versus_the_observable_universe
I just found it interesting that if the expansion rate of universe continues to accelerate, there will eventually reach a point where something can occur so far away that the light will never reach Earth b/c the rate of expansion between the two points will never allow the light to travel the distance between us
Also, there's some fun information on the wikipedia page on the observable universe.
http://en.wikipedia.org/wiki/Observable_universe#The_universe_versus_the_observable_universe
I just found it interesting that if the expansion rate of universe continues to accelerate, there will eventually reach a point where something can occur so far away that the light will never reach Earth b/c the rate of expansion between the two points will never allow the light to travel the distance between us
That's why I favour the mobius dimension style universe...after a point is reached, the universe is headed for, attracted to, and ultimately accelerates along the back side of the mobius dimension.
Two points, distant in linear location can be separated by what's essentially a membrane, adjacent to each other.
Two points, distant in linear location can be separated by what's essentially a membrane, adjacent to each other.
That sounds like Piers Anthony's space/time theory....I liked it as a teenager, and still sounds pretty good now.
JHZR2
Staff member
Originally Posted By: Pop_Rivit
Originally Posted By: JHZR2
What's to say there is such a thing as empty space?
What's to say there's not?
You tell me, Mr. Physicist?
Define "empty". No mass? No gradient of mass density over some length? What is it?
Originally Posted By: JHZR2
What's to say there is such a thing as empty space?
What's to say there's not?
You tell me, Mr. Physicist?
Define "empty". No mass? No gradient of mass density over some length? What is it?
Originally Posted By: JHZR2
Originally Posted By: Pop_Rivit
Originally Posted By: JHZR2
What's to say there is such a thing as empty space?
What's to say there's not?
You tell me, Mr. Physicist?
Define "empty". No mass? No gradient of mass density over some length? What is it?
The space between a politicians ears.
Originally Posted By: Pop_Rivit
Originally Posted By: JHZR2
What's to say there is such a thing as empty space?
What's to say there's not?
You tell me, Mr. Physicist?
Define "empty". No mass? No gradient of mass density over some length? What is it?
The space between a politicians ears.
Originally Posted By: Cujet
So, the next question is, can we observe the edge of the universe?
If we were outside of our universe, in empty space, could we observe it?
Your question has no meaning. It lacks the understanding of the word "universe". There is no outside, by definition...
Go pick up a copy of "A Brief History of Time" by Stephen Hawking....
I've tried explaining Newtonian mechanics on BITOG without much success...so, I am loathe to attempt to explain Cosmology...
So, the next question is, can we observe the edge of the universe?
If we were outside of our universe, in empty space, could we observe it?
Your question has no meaning. It lacks the understanding of the word "universe". There is no outside, by definition...
Go pick up a copy of "A Brief History of Time" by Stephen Hawking....
I've tried explaining Newtonian mechanics on BITOG without much success...so, I am loathe to attempt to explain Cosmology...
Originally Posted By: Astro14
Originally Posted By: Cujet
So, the next question is, can we observe the edge of the universe?
If we were outside of our universe, in empty space, could we observe it?
Your question has no meaning. It lacks the understanding of the word "universe". There is no outside, by definition...
Go pick up a copy of "A Brief History of Time" by Stephen Hawking....
I've tried explaining Newtonian mechanics on BITOG without much success...so, I am loathe to attempt to explain Cosmology...
I see where he's going, it's a thought exercise. Can someone attain enough speed that they could slingshot themselves through the expansion, pushing against whatever particles are presently flying the fastest, and get to the edge faster? Then, presumably, through it?
Would require a tremendous amount of energy, of course.
Originally Posted By: Cujet
So, the next question is, can we observe the edge of the universe?
If we were outside of our universe, in empty space, could we observe it?
Your question has no meaning. It lacks the understanding of the word "universe". There is no outside, by definition...
Go pick up a copy of "A Brief History of Time" by Stephen Hawking....
I've tried explaining Newtonian mechanics on BITOG without much success...so, I am loathe to attempt to explain Cosmology...
I see where he's going, it's a thought exercise. Can someone attain enough speed that they could slingshot themselves through the expansion, pushing against whatever particles are presently flying the fastest, and get to the edge faster? Then, presumably, through it?
Would require a tremendous amount of energy, of course.
Originally Posted By: eljefino
Originally Posted By: Astro14
Originally Posted By: Cujet
So, the next question is, can we observe the edge of the universe?
If we were outside of our universe, in empty space, could we observe it?
Your question has no meaning. It lacks the understanding of the word "universe". There is no outside, by definition...
Go pick up a copy of "A Brief History of Time" by Stephen Hawking....
I've tried explaining Newtonian mechanics on BITOG without much success...so, I am loathe to attempt to explain Cosmology...
I see where he's going, it's a thought exercise. Can someone attain enough speed that they could slingshot themselves through the expansion, pushing against whatever particles are presently flying the fastest, and get to the edge faster? Then, presumably, through it?
Would require a tremendous amount of energy, of course.
A thought exercise...predicated on a different set of values and parameters than exist in the observable universe....is still meaningless...it reaches a conclusion that would have no bearing on the universe in which we live...
Look, the physical laws that define existence, things like space itself, are inherent in the universe...there is no "outside" because those laws only exist here, in this universe, so there simply is no "outside"...the term is without meaning.
So, slingshot? Through the expansion? Fastest known particles are photons. Einstein's thought experiment, proven through observation, known as Relativity, concludes that you can't travel faster than a photon. To accelerate a mass, any mass, no matter how small, to the speed of light would take infinite energy. Not a lot. Not tremendous. Infinite.
The "edge" of the universe, at present, is 14 Billion Light-Years away...that's as far as we can see, because that takes us back to the beginning of the universe. If we were to start out now, in our impossible-to-build ship, that travels at the speed of light, it would take us 14 Billion Years to get as far as we can now see.
That's a long time. Time enough that more expansion would have taken place...and we would never get to an "edge"...
For the impossible-to-build ship: How would you accelerate that mass? What method of propulsion? This is a simple physics question...Newton's laws kind of stuff...given the infinite energy required, it's a bit of an engineering challenge.
Even the Saturn V - one of the most powerful vehicles ever built - could only accelerate the Apollo to 10 to 11 KM/s...the fastest manned vehicle ever built. Voyager took 30 years to get to the edge of our solar system traveling at roughly 17 KM/s (that's really fast by the way, about 40,000 MPH).
But the speed of light is 300,000 KM/s. So, our fastest vehicle ever, at 17 KM/s, has reached a velocity of roughly 0.00006 that of light. 6 one-thousands of one percent of the speed of light.
We have a long way to go to get even close to relativistic velocities, to get to, say 10% the speed of light, that might make reaching the nearest star achievable...it would still take over 30 years at that speed...but at least it would be within a human lifetime...and if we could get to 10% of light speed...it would take us 140 Billion years to reach the limit of what we can now see, and by then the universe will likely have ended...
The universe is so impossibly big...that it's difficult to comprehend...
Originally Posted By: Astro14
Originally Posted By: Cujet
So, the next question is, can we observe the edge of the universe?
If we were outside of our universe, in empty space, could we observe it?
Your question has no meaning. It lacks the understanding of the word "universe". There is no outside, by definition...
Go pick up a copy of "A Brief History of Time" by Stephen Hawking....
I've tried explaining Newtonian mechanics on BITOG without much success...so, I am loathe to attempt to explain Cosmology...
I see where he's going, it's a thought exercise. Can someone attain enough speed that they could slingshot themselves through the expansion, pushing against whatever particles are presently flying the fastest, and get to the edge faster? Then, presumably, through it?
Would require a tremendous amount of energy, of course.
A thought exercise...predicated on a different set of values and parameters than exist in the observable universe....is still meaningless...it reaches a conclusion that would have no bearing on the universe in which we live...
Look, the physical laws that define existence, things like space itself, are inherent in the universe...there is no "outside" because those laws only exist here, in this universe, so there simply is no "outside"...the term is without meaning.
So, slingshot? Through the expansion? Fastest known particles are photons. Einstein's thought experiment, proven through observation, known as Relativity, concludes that you can't travel faster than a photon. To accelerate a mass, any mass, no matter how small, to the speed of light would take infinite energy. Not a lot. Not tremendous. Infinite.
The "edge" of the universe, at present, is 14 Billion Light-Years away...that's as far as we can see, because that takes us back to the beginning of the universe. If we were to start out now, in our impossible-to-build ship, that travels at the speed of light, it would take us 14 Billion Years to get as far as we can now see.
That's a long time. Time enough that more expansion would have taken place...and we would never get to an "edge"...
For the impossible-to-build ship: How would you accelerate that mass? What method of propulsion? This is a simple physics question...Newton's laws kind of stuff...given the infinite energy required, it's a bit of an engineering challenge.
Even the Saturn V - one of the most powerful vehicles ever built - could only accelerate the Apollo to 10 to 11 KM/s...the fastest manned vehicle ever built. Voyager took 30 years to get to the edge of our solar system traveling at roughly 17 KM/s (that's really fast by the way, about 40,000 MPH).
But the speed of light is 300,000 KM/s. So, our fastest vehicle ever, at 17 KM/s, has reached a velocity of roughly 0.00006 that of light. 6 one-thousands of one percent of the speed of light.
We have a long way to go to get even close to relativistic velocities, to get to, say 10% the speed of light, that might make reaching the nearest star achievable...it would still take over 30 years at that speed...but at least it would be within a human lifetime...and if we could get to 10% of light speed...it would take us 140 Billion years to reach the limit of what we can now see, and by then the universe will likely have ended...
The universe is so impossibly big...that it's difficult to comprehend...
Originally Posted By: buster
Multi universes? Multiverses?
Suggested by the math (multiple solutions)...impossible to prove or disprove...but again, without being able to prove or disprove, meaningless...
Multi universes? Multiverses?
Suggested by the math (multiple solutions)...impossible to prove or disprove...but again, without being able to prove or disprove, meaningless...
Quote:
For the impossible-to-build ship: How would you accelerate that mass? What method of propulsion?
I saw something that was supposed to be plausible where the ship would destroy space in front of it and create new space behind it.
This would allow FTL without Newtonian acceleration and relativistic problems.
For the impossible-to-build ship: How would you accelerate that mass? What method of propulsion?
I saw something that was supposed to be plausible where the ship would destroy space in front of it and create new space behind it.
This would allow FTL without Newtonian acceleration and relativistic problems.
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