--Photo by Rig Manager for Global Marine Drilling in St. Johns,Newfoundland.
What eyes can see is but a sliver of what is!
What lies Beyond the observable, beyond the known?
How much of the universe extends not only Beyond what our eyes can see,
but Beyond what is accessible with even our most powerful instruments?
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Words of the Secrets
The world is visible,
but its essence is secret.
The essence is its message.
The world is in the words.
A word comes from the heart
and has hundreds of faces.
Each face has a thousand strings.
Sounds come from them like music from a harp.
No words remain on the tongue,
but the heart is still filled by words.
The world vanishes,
but God remains.
The words of the secrets
that were revealed are now gone,
but their meaning lives on
in the heart.
The Rumi
Nevit O. Ergin
Will Johnson
Inner Traditions,
Vermont
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Nothing is harder, yet nothing is more necessary, than to speak of certain things whose existence is neither demonstrable nor probable. The very fact that serious and conscientious men and women treat them as existing things brings them a step closer to existence and to the possibility of being born.
- - Hermann Hesse
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Date: Wed, 29 Mar 2006 15:07:16 -0800 (PST)
From: "bill dality"
Subject: playing with the expansion velocity of space
To: tomas @yahoo.ca
The outer (spatiotemporal) limits/horizon of the universe
At the current rate of acceleration ,how long will it take for the speed of expansion of the universe to reach and exceed light speed and therefore reach the limit of expansion ?
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The Hubble Constant is a measure of how fast the universe is currently expanding . The current value of
~70 km sec-1 Mpc-1 is derived empirically from a number of methods as reported by the Hubble Key Project . It is also consistent with the WMAP results.
The megaparsec (Mpc) is a unit of distance equal to 1 million parsecs or 3.26 milliion light years. What the value of the Hubble constant (H0) indicates is the rate at which galaxies in the local universe should be receding due to expansion. So a galaxy 1 Mpc away should have a velocity of 70 km/sec. At 2 Mpc 140 km/sec. At 10 Mpc 700 km/sec. At 20 Mpc 1400 km/sec. At 100 Mpc 7000 km/sec. And so on.
Therefore at 4 285.71429Mpc the expansion velocity reaches light speed of 3 X 10^6 km/sec
since 1Mpc (1 million parsecs) = 3.26 million light years,
4 285.71429Mpc =4 285.71429Mpc X 3.26 = 13 ,971.4286 million light years =13.9 billion light years
Is it significant that this number (wch is in units of spatial distance) is exactly the same as the known age (in units of time)of the universe of 14 billion years!
What does this mean?
It means that in 14 billion years since the Big Bang the expansion wave front of the universe has reached light speed! Everything at the outer edge of the universe is traveling at light speed!Having reached light speed this part of the universe (the expanding wave front) cannot get any older because at light speed, time stops(stands still). Therefore the universe cannot get any older!
If the universe were to get any older and continued to expand ,it's outermost expansion velocity would exceed the speed of light ,the direction of time would be reversed ,and the universe would begin to get younger!
If the spatial separation between an observer and a light source is increasing at light speed, then the emitted light can never catch up to the observer and can never be seen by him.Indeed if the rate of expansion is equal to light speed ,then the light (wch is moving as fast as it can ) isn't really moving at all,is it?Light cannot fight its way "upstream" against the stretching Universe to reach us. For each mile a photon moves towards us ,expanding space lenghtens by a mile,so the photon cannot advance but only treads water/space.It cannot outrun the expansion of space!
Moreover we can never see a light-emitting object that is speeding away from us at greater than the speed of light--it's light can never reach us.Light emitted from a galaxy moving away from us at the speed of light would remain at a constant distance with respect to us.
Hence the outer limit of the universe may only be a perceptual horizon--an illusion . We can only surmise how much of the universe lies beyond this horizon!
Let's imagine a simpler scenario:
A photon is emitted from planet earth and speeds away at light speed.Now jumping to the observational frame of reference of the photon and looking back,it would appear from the photon's perspective that it is stationary and it is the earth wch is receding at light speed.This is only reasonable.
But some very odd implications here:If only light can travel at the speed of light,and the earth is traveling away from the photon at the speed of light ,would it then not appear from the point of view of the photon to be light?!
Does this mean that any object wch attains light speed loses it's mass and comes to appear to be light (acquires the appearance of light)?.Then how can we distinquish between matter and light?
But it gets weirder:
According to Einstein an object of mass(such as in this case the earth),if it attained light speed would become infinitely massive.So from the perspective of the emitted photon the earth would become infinitely massive,right?
Wrong! From the perspective of the photon the earth would disappear(as in "poof!")--it would cease to be observable.Because any subsequent photon leaving the earth (and carrying information of it's existence)would never catch up to the first photon and would hence never be seen by and from the first photon.
This means that if you were riding a light beam ,and looked in your rear view mirror all you would ever see is darkness.It would in effect be like looking into a black hole from wch no light can escape!
The only way to see light would be to slow down and allow photons coming up from behind to sneak up and catch up to you,but this is impossible because photons have only one speed and can't slow down (unless they morph into a material particle or pass through a transparent denser medium such as water or diamond.An opaque medium would bring a photon to a dead stop---300,000 kilometers per second to 0 km/sec in zero seconds!)How can something undergo that kind of decelleration? perhaps horizontal motion is transformed into in situ vibrational and rotational motion?
Photons are being perpetually emitted from the earth,but the earth does not cease to exist ,nor does it's mass increase(from the perspective of the earth). And yet from the perspective of the emitted photons ,the earth ceases to be observable.
It's all smoke and mirrors!
Because some object ceases to be observable does not mean that it ceases to exist.
Conclusion:Just because we can't see something ,doesn't mean it doesn't exist! It is entirely likely that most of what exists is not visible/observable.
Perhaps what we detect with our senses merely blinds us to the much greater part of the universe wch is unobservable(veiled behind a horizon).
Perhaps there will always be a horizon to our vision of the universe beyond wch we cannot see and cannot know.Our perception can never encompass the entire universe.
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1 Mpc=1megaparsec=3.08396 × 1019 km
Hence 4 285.71429Mpc =4 285.71429 x 3.08396 × 1019 km =
4 .28571429 x 3.08396 x 10^19km=13.2166702 x10^19 km=
1.32 x 10^20 km
Light travels at 300,000 kilometers per second. So, in one year light travels a distance of about 5,880,000,000,000 miles or 9,460,000,000,000 kilometers (9.46 X 10^12 km.).
In 3.26 million light years (3.26 X 10^6 light years =1 Mpc=1megaparsec) light travels ( 3.26 X 10^6 light years ) X (9.46 X 10^12 km) =3.08396 × 1019 km
Some day I will forget the need to calculate the distance and time between here and now!>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
bill dality
Einstein said that space and time are welded together into a uniform four-dimensional continuum.
With regard to the variable speed of time flow, Einstein said that the greater the velocity of an observational/inertial frame of reference the slower the speed at wch time flows.
When things travel at speeds close to the speed of light, time slows down. For example, if you were travelling for 10 years in a spaceship that could go at 95% the speed of light then 32 years would go by for the people that stayed on Earth.
Thus time slows down as one approachs the speed of light,and at the speed of light time stops and stands still.
What is really interesting is that theoretically beyond "light speed", time reverses and flows backwards!
The implication is that if and when the speed of expansion of the universe exceeds the speed of light, the expansion stops and the reverse process of spatial contraction begins!That is, the universe begins a return (both spatially and temporally)to it's origin.!
The question of whether or not the universe would continue to expand forever has centered upon how much total mass/energy the universe contains.
But by this new line of thought the total mass/energy content of the universe is irrelevent to this question.
The answer depends exclusively on whether the speed of expansion can reach and exceed the speed of light!
P.Z.Current measurements indicate that the speed of expansion of space is accelerating!
At the current rate of acceleration ,how long will it take for the speed of expansion of the universe to reach and exceed light speed and therefore reach the limit of expansion ?
