Light (Page 2)

Blackshoes: Interesting

Blackshoes ;Just noticed Corvin ,Changed his name to Corwin'. That was fast

calybonos: Traveling at the speed of light, one could not simply stop at any spot or destination, as the resulting G- forces from going from 186 thousand miles(and some change) per second to a full stop would cause you to shit your pants.

And no grand entrance is worth that.

Blackshoes: Yet : according to time dilation Light is instantaneous ,from the protons point of view ",
It's our observation that shows light to have a speed limit '.
Very difficult Concept for me to wrap my head around ..

lori100: No. 2627: The Bohr-Einstein Debates

uh.edu/engines/epi2627.htm

University of Houston

The 1927 conference on quantum mechanics was held to discuss how the many seemingly contradictory observations could be reconciled. Schrödinger and de Broglie showed up with their ideas. But the eight-hundred pound gorilla was Bohr. In what later came to be called the Copenhagen interpretation, Bohr proposed that wave equations described where entities like electrons could be, but, the entities didn't actually exist as particles until someone went looking for them. The act of observation caused existence. In Bohr's own words, the entities in question had no "independent reality in the ordinary physical sense."

Blackshoes: I'm sorry lori I don't understand this ?

no independent reality in the ordinary physical sense."

lori100: Bohr also said it of the moon...you can't prove it exists until someone looks at it....for anything to exist it needs a mind to perceive it...does it exist when no one is perceiving it?...sort of like this------------Solipsism (Listeni/ˈsɒlᵻpsɪzəm/; from Latin solus, meaning "alone", and ipse, meaning "self[1] is the philosophical idea that only one's own mind is sure to exist. As an epistemological position, solipsism holds that knowledge of anything outside one's own mind is unsure; the external world and other minds cannot be known and might not exist outside of the mind.

Corwin: Just ignore Lori's comments, Bobby... she doesn't even understand what she's saying (because she's talking nonsense), and it has absolutely nothing to do with your questions in your original post.

Lori - Bobby's questions were regarding general Relativity... perhaps you should create your own discussion forum to address Solipsism and Philosophical Epistemology.

Blackshoes: Corwin I wonder if you could also answer this ? Do the telescopes reach the end of the Known Universe ? In other words if we point the telescope in all directions .Does it seem that Earth is within the center or does the Universe go on forever ?
If so ', can they tell what our position is ?

Corwin: I can answer that.

Our telescopes can only see a bit under 14 billion light-years distant, which is the age of the Universe. At that distance all we see is the microwave background radiation, which is the afterglow of the Big Bang. Then as we observe closer objects, we see the first galaxies forming (known as Quasars ), and basically the story of the evolution of the Universe from the beginning until now... kind of like reading the pages of a book. The farther the distance you look, the farther back in time you observe. So we see the "beginning" of the Universe in all directions at that 13.78 billion light-year distance.

The Universe is not infinite... since it is calculated to have had a beginning where it was very small, it has therefor expanded to a finite size. From our perspective, we appear to be at the center of a spherical Universe with a radius of 13.78 billion light-years, but that is only our visual perspective. It is believed to be much larger than that, as it is calculated that during the very early Universe there was a period known as the "Inflationary period", where Space/Time expanded much faster than the speed of light. This seems contradictory, as nothing "within" the Universe can exceed the speed of light... but it was Space/Time itself that was expanding.

So, because of this limitation of the speed of light, we don't really know where our position is overall, nor can we deduce with any certainty exactly how big it really is... we simply appear to be in the center (which would be very unlikely). But possibly the idea of a "center" could be meaningless... as the "outer limits" of the Universe is expanding at the speed of light, we could never reach it anyways, so the idea of an "outer edge" is kind of a moot point.

Neat stuff, eh? Oh, and don't feel bad if you find it hard to wrap your head around this... everybody does, really. Our minds are not really intended to fully grasp this sort of thing... it's not a necessary survival skill to comprehend the Universe in its entirety, or to comprehend 11-dimensional space (possibly more).
We only need to comprehend a 3-dimensional world to survive, so anything beyond that is counter-intuitive.

Blackshoes: Actuelly That's rather easy for me to understand . So Earth from it's perspective, appears to be at the center of what we can see ,of the known universe '. (which would be very unlikely).
But accoding to what we know ', Without any assumption we are in the center ? Is that unfair to say ?

Corwin: Well... we're not really at the center of anything... we're not at the center of the solar system... we're not at the center of the Milky Way galaxy... the Milky Way is at the outer edge of the Virgo Supercluster of galaxies...
... to assume that the sphere of the visible universe (which is roughly 28 billion light-years across ) would actually be at the very center of the entire universe (which is calculated to be at least 160 billion light-years across ) would be one VERY big assumption indeed.

Blackshoes: I'm not sure I understand ? If we can only see 14 Billion light years in each and every direction .I would imagine we sit somewhere close to the center ?
If we could only see 5 billion years one way direction and then turn behind to the other direction and only see 23 billion years that way ', it would mean that were no where near the center .Of course that's only assuming that the Universre has a end to it .Which isn't likely for all we know ?
However : we don't know', do we ?
So it's just assumptions ?

Corwin: Light travels at a fixed speed... so of course the "visible sphere" will be of equal distance in all directions. If we traveled 10 billion light-years away from the Earth, we would still appear to be within a visible sphere 14 light-years in all directions.

And seeing how the universe is likely bigger than 160 billion light-years across it's unlikely that we would be in the exact center. But because we can't see any further than 14 billion light-years, there's really no way to know.

Blackshoes: Exactly ". It's not possible to know where we sit in the Universe neither now nor anytime in the future ? I would like to know', whether new stars or galaxies are appearing at the edge of the universe .That would prove that the universe is larger than what we see !

I'm sure they have already asked this Question 50 years ago', and have already mapped a small section so as to test this ?
Also If you believe the Universe Id larger than 180 billion years across ? How old is the Universe ?

Corwin: Yah. Unfortunately, Science does have it's limitations. And there are just some things that we will never know. Interesting to ponder about though.

ghostgeek: Isn't the universe supposed to be thirteen to fourteen billion years old? Seems you have to add in a little super fast inflation to take account of its size. All very confusing.

Corwin: Yah... 13.78 billion years to be exact. That's as distant (and as far back in time) as we can observe. At that distance all we see is the microwave background glow of the aftermath of the Big Bang.

And yes, the Inflationary Period very early on is what's responsible for its immense size.

Oh, and in regards to Bobby's question about seeing "new" galaxies forming at great distance... we can only see the past... if there is a new galaxy forming, say 10 billion light years away, we wouldn't see it happening for another 10 billion years.

duncan124:

I don't think what we have been told about the universe is quite right and I doubt very much if it is as they have described.

In fact I think it is far more dangerous.

Blackshoes: If all we can see it's said to be about 14 billion years old ',How can it be bigger than that ?
I Wasn't asking if we see galaxies forming ? I asked if we see stars or galaxies appearing as time goes by ?
This isn't making any sense at this time ? The edge of the Universre only shows the beginning of the universe? Wouldn't the beginning come from the center', and not the circumference of the edge ?( accepting that the Big Bang happen )

ghostgeek: We can only see as far as light has had time to travel to us. So if the universe is approximately fourteen billion years old that is how far out we can see. Light from any stars further away hasn't yet had time to reach us. But the longer we keep watching the further out we'll see and presumably the more stars will become visible to us.

duncan124:

I noticed the constellations have changed; and even their names are different now.

http://spaceplace.nasa.gov/review/dr-marc-space/constellations.html


There are loads of pages about it but the ultra conservative Google wont find so many.

I think Orion changed the most

Blackshoes: Exactly Ghost ', I would assume they've been searching for some time for prove that the universe is bigger than what we saw 50 years ago ?
If so have they found anything?
Noting how large the Universe is ",It should be able to notice a few more stars in just a few years let alone 50 ?

duncan124:

The rules of perspective must apply. So after so many billion miles the star would be smaller then a photon and none of its light would ever reach us as it would be too spaced out.

ghostgeek: I think they've got over that problem by building bigger telescopes.

duncan124:

Hubble came back with pictures that were grey mist.

It could have been anything.