Set me straight: Universe Size & Age = FTL motion?

[Reverend]

^Unless I misread that, that sounds more like the speed remaining constant while the distance between the two points is increasing. If the speed of light changed then wouldn't it be that the distance increases (or decreases, either way) and yet the transit time remains the same?

 

[chardman]

Tacky,

Dude, they're called question marks. Learn how to use them.

I'll concede that there was a brief period where the physical laws and constants hadn't been firmly nailed down. This period lasted a whopping 10 to the power of negative 30 seconds or thereabouts. So for all practical purposes, the physical laws and constants came into being at the time of the bang itself.

Virtually none of the theories I've heard to explain the larger than expected size of the universe, attribute it to a mythical time when superluminal travel was possible, or which suspends (even temporarily) the notion of lightspeed as a UC. Some explain it pretty much along the same lines as BJ did, while others address a perceived but mathematically non-existent paradox within the theory of Special Relativity (the differences between "True Time" and "Local Time", also known as the "Relativity of simultaneity"). Here's a link. Sorry, it's only wiki, but it should be enough to give everyone a very basic overview. LINK

Imagine two planets which are moving directly away from each other, traveling at 99.999% of the speed of light. Now imagine that each of these planets launches a scout ship to check out the path ahead. These scout ships also travel at just a hair under the speed of light. Now let's look at the situation one year later. The two moving planets are slightly less than 1 light year further from where they were when we first spotted them, but are nearly 2LY farther from one another. Moreover, their scout ships are now almost 4LY farther from each other! Absolutely nothing has traveled faster than light (relative to their point of origin), yet the relative distance between the two scout ships would seem to indicate a speed much faster than light. A spatial difference of nearly 4LY in 1 actual year.

Now, while I accept the above explanation, I don't really understand the finer points of it all, and sincerely doubt that any of you (most especially Tacky) really grasp it fully either. Still, I understand enough to see that it doesn't involve a mythical exception to the notion of light being a truly universal constant.

 

[Jadzia]

Imagine two planets which are moving directly away from each other, traveling at 99.999% of the speed of light. Now imagine that each of these planets launches a scout ship to check out the path ahead. These scout ships also travel at just a hair under the speed of light. Now let's look at the situation one year later. The two moving planets are slightly less than 1 light year further from where they were when we first spotted them, but are nearly 2LY farther from one another. Moreover, their scout ships are now almost 4LY farther from each other! Absolutely nothing has traveled faster than light (relative to their point of origin), yet the relative distance between the two scout ships would seem to indicate a speed much faster than light. A spatial difference of nearly 4LY in 1 actual year.

You're adding together speeds like you add together money. That's not really what the relativity theory says happens.

speed_combined = speed_1 + speed_2

...is only true when the speeds are small.


iirc, the formula should be:

speed_combined = [ speed_1 + speed_2 ] / R

where R^2 = 1 + [ speed_1 * speed_2 ] / speed_of_light ^2

 

[Crazy Eddie]

So you're saying that the speed of light isn't a universal constant but a wholly conditional one?

Certainly in the conditions the universe was in during the first half-second of the Big Bang (and probably shortly after) it wasn't a constant.

In point of fact, there's nothing in Special Relativity that stipulates it must be constant everywhere. It wouldn't violate any physical laws we're accustomed to, it would simply involve different objects having completely different rest energies despite nominally having the same mass. It could still be locally constant ("locally" meaning "in every way that matters") but this need not be true over cosmic distances. In point of fact, it seems NOT to be given the OP of this thread.

 

[paudemge]

Imagine two planets which are moving directly away from each other, traveling at 99.999% of the speed of light. Now imagine that each of these planets launches a scout ship to check out the path ahead. These scout ships also travel at just a hair under the speed of light. Now let's look at the situation one year later. The two moving planets are slightly less than 1 light year further from where they were when we first spotted them, but are nearly 2LY farther from one another. Moreover, their scout ships are now almost 4LY farther from each other! Absolutely nothing has traveled faster than light (relative to their point of origin), yet the relative distance between the two scout ships would seem to indicate a speed much faster than light. A spatial difference of nearly 4LY in 1 actual year.

You forget that time and distance are not constant between each reference. There is no such thing as 'actual year'

 

[All Seeing Eye]

Tacky,

Dude, they're called question marks. Learn how to use them.

WTF

My last post did have question marks in them. What the hell are you going on about man.

 

[chardman]

But we're talking about a time when the universe was in the process of being created and was not yet created. How can you have a universal constant at a time when the universe wasn't yet created.
In fact time apparently didn't exist before the big bang and was created at that moment so how can you have universal constants when time (like the physical universe) is in the middle of being created.

No question marks on these questions. That's what I'm on about. Also:

My last post did have question marks in them. What the hell are you going on about man.

You even spaced putting a question mark at the end of your question to me about pointing out your omission of question marks.

 

[All Seeing Eye]

Those are rhetorical questions and don't require a question mark for reasons i'll explain. You see it's more along the lines of when you are talking to yourself out loud.

The ones that are questions to be answered are the ones with question marks next to them.

So keep that in mind in future, if I say something that sounds like a question but it doesn't have a question mark i'm speaking rhetorically and don't expect an answer.
On an internet message board if someone speaks rhetorically then there's no way to convey that, no way to make them understand that and the closest way to do it is to omit a question mark.

 

[chardman]

Sorry, but you don't just get to make up entirely new rules of punctuation to "justify" your past mistakes. Rhetorical questions are still questions, and are punctuated as such.

So I'll keep this in mind in future: Tachyon Shield doesn't understand the fundamentals of real punctuation any better than he understands the fundamentals of basic physics.

 

[Jadzia]

Sorry, but you don't just get to make up entirely new rules of punctuation to "justify" your past mistakes. Rhetorical questions are still questions, and are punctuated as such.

So I'll keep this in mind in future: Tachyon Shield doesn't understand the fundamentals of real punctuation any better than he understands the fundamentals of basic physics.

This is totally petty and irrelevant chardman. I've cautioned you before about coming into sci-tech bringing ridicule, and these kind of posts you've been making recently are only made to annoy other posters. Consider this a final friendly warning.

 

[Trekker4747]

In my tiny, universally insignificant, mind I think an early post of "it's like blowing up a balloon!" makes the most sense.

You take an uninflated ballon and with a Sharpie you put two dots on it right next to each other. Traveling at the speed of light it takes an instant to move between these two points.

Now you blow up the balloon. As the air you put in it expands the balloon the two points on it now move further and further apart from one another meaning that now traveling at C between these two points takes longer. The two points haven't really moved the space between them has expanded.

Now, let us say that at the begining these two points were a "light year" apart in physical distance. When you expanded the balloon you had to also expand your "concept" of what a light year is. You cannot change one without changing the other. So, NOW those two points are still a "light year apart" but now that light year is a greater distance. Since light moves at a constant speed and cannot be changed (unless you change the medium it is traveling through, through a medium c is a constant) it will now take light longer to move between those two points.

As someone above said, the universe's continuum is expanding and dragging the matter of the universe along with it.

Stop thinking of the universe being a vast, empty, space and the galaxies within it are moving apart from one another like the plasma of a fire-explosion and thing of, well, a baloon.

 

[FlyingLemons]

With regards to the OP's question, it is believed by physicists that in the first moments of the Bang, the size of the universe was blown up by a phenomenon known as cosmological inflation, a period of superluminal expansion driven by something known as a scalar field, blowing up small quantum mechanical fluctuations to giant size leading to the formation of structure, with the scalar field decaying to become the matter we see today. Admittedly, this is quite oversimplified, but that's basically the gist of what happened.

The reason this can actually happen is due to the fact that the universe back then was in a much denser, hotter, and energetic form than it is now. As a result, the physics back then probably included the effects of quantum gravity which we do not know much about. Essentially it's very speculative territory, and there are many highly theoretical ideas about what happened in the first moments of the universe. We hope that possibly, we might be able to find something like gravity waves or some form of observable quantum gravity phenomena that might offer us a few hints of what happened back then.

 

[RyanKCR]

In my tiny, universally insignificant, mind I think an early post of "it's like blowing up a balloon!" makes the most sense.

You take an uninflated ballon and with a Sharpie you put two dots on it right next to each other. Traveling at the speed of light it takes an instant to move between these two points.

Now you blow up the balloon. As the air you put in it expands the balloon the two points on it now move further and further apart from one another meaning that now traveling at C between these two points takes longer. The two points haven't really moved the space between them has expanded.

Now, let us say that at the begining these two points were a "light year" apart in physical distance. When you expanded the balloon you had to also expand your "concept" of what a light year is. You cannot change one without changing the other. So, NOW those two points are still a "light year apart" but now that light year is a greater distance. Since light moves at a constant speed and cannot be changed (unless you change the medium it is traveling through, through a medium c is a constant) it will now take light longer to move between those two points.

As someone above said, the universe's continuum is expanding and dragging the matter of the universe along with it.

Stop thinking of the universe being a vast, empty, space and the galaxies within it are moving apart from one another like the plasma of a fire-explosion and thing of, well, a baloon.

I've always wondered about that and that would be the reasoning behind the faster speed of light in the past. With all of that in consideration wouldn't that affect the estimated age of the universe a bit since it is estimated by the distance of the fartherest object we can observe?

 

[iguana_tonante]

FlyingLemons did an excellent job explaining inflation. I just add a few points as I understand it.

My assumption would be that the universe's size in light-years would be, at most, 2x its age, given a symmetrical expulsion of matter and the assumption that its ultimate speed could only be a fraction under the speed of light.

It is a common mistake, because the name Big Bang evokes a powerful explosion. There is no explosion at all. You should not think about it as a firework in space, but as a bubble of soap, filled with energy: as the bubble expands, the energy becomes "colder" and more diluted (highly inaccurate as a description, but the best I could conjure). Everything is happening inside the bubble, and the expansion of the bubble carries the the energy with it with a rate that has nothing to do with the velocity of the stuff inside the bubble.

In essence, this sounds exactly like warp theory to me, that we avoid exceeding SOL by warping the subjective points of the universe closer together and traveling between them at non-relativistic speeds - it sounds like this is exactly what the universe has done, altering the constants of time and space as it expanded.

Do I read this right?

More or less, yes. Only, the "super-luminal" expansion (I don't think you can attribute something like a "velocity" to the expansion, since it's space-time itself that it's expanding, but bear with me) is actualized by some high-energy quantum effect that I am really at a loss to explain without some math and graphs.

Or is it just astrophysicists hemming and hawing around the fact that the universe's size contradicts the theory of relativity?

We would never do something like that!

 

[Trekker4747]

I think we can all agree that the universe and the complexity of its origins, its nature and its makeup is far too complex for our comparitively infantile species to comprehend.

Considering the immense complexity and enormity of the universe multiplied by its staggering age; us trying to understand it is like a newborn trying to understand advanced calculus.

 

[All Seeing Eye]

If time itself was slowing down would it make the universe appear to be expanding at a faster speed? would it make the universe look like it was expanding faster?
Let's say for example that time was slowing down gradually and was tiny so us mere Humans would not notice it but over billions of years the slowdown was more noticeable would this make it appear like the universe was expanding faster when really it wasn't but time was infact slowing down?

 

[FordSVT]

If time itself was slowing down would it make the universe appear to be expanding at a faster speed? would it make the universe look like it was expanding faster?
Let's say for example that time was slowing down gradually and was tiny so us mere Humans would not notice it but over billions of years the slowdown was more noticeable would this make it appear like the universe was expanding faster when really it wasn't but time was infact slowing down?

Time isn't a constant, it's relative and subjective everywhere in the universe. But it's also not locally isolated, like some alien has us in a magic bubble that experiences time at a relatively slower rate than the rest of the entire universe (like that episode of Voyager where the planet evolved hyper-fast in it's own time-frame). Overall, on average, the universe appears to be expanding at the same rate in both space and time with differences in relative velocity.

If time was slowing down for us over time, it should be slowing down everywhere (like spacial expansion or contraction), in which case, relatively speaking, we'd both still be moving at the same rate.