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Dave W.
Info Junkie
USA
26020 Posts |
 Posted - 10/01/2008 : 22:04:07 [Permalink]
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Originally posted by bngbuck
Why does Beradilli say, "the universe underwent a brief period that defied current physical laws."
1. What current physical laws were defied? |
You should ask Beradilli, because I'm not aware of any. The inflationary period would appear to violate the law that matter can't move at or faster than c, but the matter wasn't actually moving, spacetime itself was expanding at a much-larger rate than we observe now.| 2. Is it possible to explain how space expands and what it expands into? Can you put it into words? |
The ant-and-balloon analogy is used a lot because it's a very good analogy. If you accept it, then what spacetime is expanding into is neither the ant (something within the universe) nor the balloon (spacetime itself), and we may never know what is "outside" the universe ("outside" in quotes because the universe is spacetime and everything in it, and prepositions without a proper referent often don't have any meaning, sort of like "I found my keys under yesterday"). |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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BigPapaSmurf
SFN Die Hard
3192 Posts |
Posted - 10/02/2008 : 04:51:33 [Permalink]
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| Check out Phillip K Dick's 'The Indefagatable Frog', much more interesting than the Ant and the ballon. Both are somewhat based on Zeno's paradoxs, Achilles and the Tortoise and the Dichotomy Paradox. |
"...things I have neither seen nor experienced nor heard tell of from anybody else; things, what is more, that do not in fact exist and could not ever exist at all. So my readers must not believe a word I say." -Lucian on his book True History
"...They accept such things on faith alone, without any evidence. So if a fraudulent and cunning person who knows how to take advantage of a situation comes among them, he can make himself rich in a short time." -Lucian critical of early Christians c.166 AD From his book, De Morte Peregrini |
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chaloobi
SFN Regular
1620 Posts |
Posted - 10/02/2008 : 04:57:11 [Permalink]
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Originally posted by Dave W.
Depends on how much FTL the drive can go.
If I remember the old Star Trek Technical Manual, Warp 9 was equal to 729 c. Anything more than 10.2 trillion lightyears away would remain unreachable at that speed.
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I'm thinking worm holes. Space must be so convoluted in all those extra dimensions that a shortcut could be punched through to the invisble side of the universe and probably would only take a few minutes to traverse. |
-Chaloobi
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 10/02/2008 : 06:43:24 [Permalink]
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First (to get these constants out of the way), a parsec is 3.26156 light-years. A light-year is 9,460,730,472,580.8 km. The Hubble Constant, in km/s/Mpc, is 70.1 (or thereabouts), so in Mpc/s/Mpc, H is 2.272×10-18. The speed of light is 299,792.458 km/s, so SoL is 9.716×10-15 Mpc/s.Originally posted by Ricky
b(t): distance of the "beam" of light to Earth, with time t in seconds, expressed in mega parsecs.
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b(t) = SoL*H + (D - SoL*H)e^(Ht) |
Okay, in chat last night I pointed out that if the units don't match up (and they don't in the D-SoL*H term), then something is wrong. That something is this:
b(0) is SoL*H + (D - SoL*H), or D, as it should be.
b(1) is always larger than b(0), because eH×1 is 1.000000000000000002272, and it only goes up from there.
In reality, b(1) should definitely be smaller than D when D is less than SoL/H (4,276.64 Mpc), because the two objects will be receeding at less than SoL. In fact, if D is 1 Mpc, then the speed of light is 4,276.64 times larger than the speed of expansion (after one second, a photon will have gone 299,792.458 km, but space will only have expanded by 70 km). But the b(t) equation has light always getting farther and farther from Earth, never closer.
(Note that SoL*H is 2.207×10-32, and Windows' calculator craps out on doing 1-SoL*H, or I'd present more numbers here.)
(D*H) is the instanateous rate of expansion at t=0, so (D*H)/SoL relates the speed of light to the rate of expansion. (1-((D*H)/SoL) is then how much of a photon's travel during the first second gets "applied" to its travel towards Earth, so SoL(1-((D*H)/SoL), or SoL-D*H... no, that won't work, either. It assumes that all of the expansion is "behind" the photon, but that distance is actually proportional to D...
Crap. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Simon
SFN Regular
USA
1992 Posts |
Posted - 10/02/2008 : 08:52:29 [Permalink]
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| [The ant-and-balloon analogy is used a lot |
You mean I am not the genius vulgarizer I thought I was?
Aaaaaw...  |
Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
Carl Sagan - 1996 |
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chaloobi
SFN Regular
1620 Posts |
Posted - 10/02/2008 : 09:08:06 [Permalink]
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Originally posted by Simon
| [The ant-and-balloon analogy is used a lot |
You mean I am not the genius vulgarizer I thought I was?
Aaaaaw...
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There really isn't anything new anymore. Most everything's been thought of and expressed by somebody at some point. |
-Chaloobi
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Ricky
SFN Die Hard
USA
4907 Posts |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 10/02/2008 : 12:10:55 [Permalink]
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Originally posted by Ricky
Oh for fuck's sake. I couldn't take a god damn simple integral... even though I did it 5 times.
New equation:
b(t) = SoL/H + (D - SoL/H)e^(Ht) |
So what you're saying is that the distance between the photon and Earth is equal to...The distance between A and B
minus
The radius of the observable universe
multiplied by
The expansion factor for the universe at time t
plus
The radius of the observable universe
And b(t) also equals o(t) + (SoL/H)(1-eHt) if I did the algebra correctly. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Ricky
SFN Die Hard
USA
4907 Posts |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 10/02/2008 : 15:33:17 [Permalink]
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Here, Ricky:Originally posted by Ricky
New equation:
b(t) = SoL/H + (D - SoL/H)e^(Ht) |
So what you're saying is that the distance between the photon and Earth is equal to...The distance between A and B (D)
minus
The radius of the observable universe (SoL/H)
multiplied by
The expansion factor for the universe at time t (eHt)
plus
The radius of the observable universe (SoL/H)
Rather than earth and some other object, I've been thinking of D as the distance between points A and B (at t=0). |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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bngbuck
SFN Addict
USA
2437 Posts |
Posted - 10/02/2008 : 16:33:23 [Permalink]
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Dave.....
In your answer to my question, you state, | ....but the matter wasn't actually moving, spacetime itself was expanding at a much-larger rate than we observe now. |
Beradilli says, | .....during this time, called inflation, space itself expanded at a rate much, much faster than the speed of light. As a result, some of the matter formed with the big bang was pulled more than 13.7 billion light-years away..... |
I will fully admit beforehand to both ignorance and stupidity, so comments on those unfortunate truths won't be necessary; but why does his statement sound like - matter was moved at a speed greater than the speed of light - a situation we all know is an impossibility?
I'm sure the answer is there right in front of my admittedly feeble eyes, but I need someone to point it out to me, hopefully gently!
If it is, in fact, merely another misstaken and incorrect statement by Beradilli, do you feel he has grossly misquoted the he refers to, and the whole article may be in some question because of this particular journalist's misstatements? |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 10/02/2008 : 17:47:19 [Permalink]
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| Phil Berardelli may be an excellent science writer, but he's writing for a largely lay audience, he's probably got a word limit, and probably an editor. But most importantly, he's going to use shorthand and metaphors because it is not his intent to write a precisely worded cosmology textbook into every article. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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bngbuck
SFN Addict
USA
2437 Posts |
Posted - 10/02/2008 : 21:36:10 [Permalink]
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Dave.....
I got you! In other words, take the article metaphorically! |
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BigPapaSmurf
SFN Die Hard
3192 Posts |
Posted - 10/03/2008 : 04:34:52 [Permalink]
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Matter is like surfers paddling as fast as they can, their speed is limited unless they ride the wave so to speak.
Or better, matter is like test driving cars on either side of the Atlantic, when judging speed you don't even notice that the continents are being pushed apart. In space the continents are being pushed apart at blazing speeds.
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"...things I have neither seen nor experienced nor heard tell of from anybody else; things, what is more, that do not in fact exist and could not ever exist at all. So my readers must not believe a word I say." -Lucian on his book True History
"...They accept such things on faith alone, without any evidence. So if a fraudulent and cunning person who knows how to take advantage of a situation comes among them, he can make himself rich in a short time." -Lucian critical of early Christians c.166 AD From his book, De Morte Peregrini |
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bngbuck
SFN Addict
USA
2437 Posts |
Posted - 10/03/2008 : 06:02:29 [Permalink]
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BPS and great dane 80 (if you're "lurking").....
Wiki defines space thus...| Space is the extent within which matter is physically extended and objects and events have positions relative to one another[1]. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of the boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the universe although disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework. |
What is your understanding of the meaning of the word "space", as used in the context of particle physics, and/or astrophysics? |
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Dark Flow - Out there Beyond the Horizon
