Dark Energy is Light Energy - Page 3

Jerry · #61 (**permalink**) 01-May-2006, 03:05 AM

Quote:

Originally Posted by Peter Wilson

The expansion of the universe is a manifestation of the principle of Conservation of Energy.

Space expands in GR as naturally as water flows downhill.

You lose me here, because space should be defined as that which is nothing. Yes, I know Einstein's mathematicians came up with abstractions that give space dynamic properties, but rationally, these are absurbities on the same order as the emporers naked robe.

The fact is, Newton's calculations don't properly predict orbits. Einstein took a page from Aristotle and told us that is because it is the nature of space to expand and contract.

Peter Wilson · #62 (**permalink**) 01-May-2006, 05:17 PM

The odd thing is, the cause-effect relation between expansion and contraction is perfectly obvious in all non-infinite systems.

Take a core-collapse supernova. We think of these as explosions, but in fact, they are more intrinsically implosions. We would say the "cause" is gravitational contraction, and the "effect" is the observed expansion.

Take another example: NASA using Jupiter to sling-shot a space probe to Saturn. The space-probe's orbit expands, while Jupiter's orbit contracts. Again, straight-forward cause-effect: the contaction of Jupiter's orbit "causes" the expansion of the space-probe's orbit.

Another example: "Evaporation" of globular clusters. What happens in a crowded globular cluster is a sort-of random gravitational interaction among stars. And in these interactions, low-mass stars tend to pick up high velocity, whereas massive stars tend not to. So occasionally, a low-mass star will pick up enough velocity to escape, and it will "evaporate" (expand)from the cluster. The result, when you do the energy balance, is that some massive star must have lost gravitational energy, and is now closer to the center of the cluster. Again, it is straight-forward cause-effect: the contraction of the orbits of massive stars in the cluster "causes" the expansion of the orbits of low-mass stars.

In all these examples, gravitational contraction of one part of the system "causes" expansion in another part. Gravity causes the SN to explode (expand); gravity causes the orbit of NASA's space probe to expand; gravity causes globular clusters to expand; gravity is causing the moon's orbit to expand. Gravity causes expansion in all these systems.

All I am saying is this same cause-effect (action/reaction) principle applies to the universe at-large: On-going local contraction everywhere causes residual on-going cosmic expansion, "as naturally" as water flows down-hill.

Jerry · #63 (**permalink**) 02-May-2006, 06:54 PM

Quote:

Originally Posted by Peter Wilson

The odd thing is, the cause-effect relation between expansion and contraction is perfectly obvious in all non-infinite systems.

Take a core-collapse supernova. We think of these as explosions, but in fact, they are more intrinsically implosions. We would say the "cause" is gravitational contraction, and the "effect" is the observed expansion.

Not a good argument - if we understand the SN Ia process: To create the same type of explosion, we use high (conventional) explosives to trigger the same chain of events. The source of the initial energy - gravity or high energy explosives - is irrelevant.

Quote:

Take another example: NASA using Jupiter to sling-shot a space probe to Saturn. The space-probe's orbit expands, while Jupiter's orbit contracts. Again, straight-forward cause-effect: the contaction of Jupiter's orbit "causes" the expansion of the space-probe's orbit.

Another poor example - here, the gravitational assist is exactly akin to tacking a sailboat into the wind. Planets can just as easily be used to provide gravitational braking - I think the Messinger probe uses both Mercury and Venus to help it slow down.

Quote:

All I am saying is this same cause-effect (action/reaction) principle applies to the universe at-large: On-going local contraction everywhere causes residual on-going cosmic expansion, "as naturally" as water flows down-hill.

If you want to argue that gravitational squeezing of matter eventually leads to the release of primal energy in some cases, that may be true, but it is difficult to argue that all bodies that are contracting are causing expansion somewhere else. Since with these examples, general energy sources can be substituted for gravity, these examples are not definitive.

Nereid · #64 (**permalink**) 02-May-2006, 07:39 PM

Quote:

Originally Posted by Peter Wilson

[snip]

Interestingly, for a body of a given ATM, the expansion velocity does not depend on the distance from the source. Suppose the radiation pressure from the sun is pushing an asteroid-belt asteroid of a given ATM outward at 1 m/yr, and there is a Kuiper-belt object with the same ATM, only 10 times more distant. Ten times farther away, solar radiation pressure is 100 times weaker, due to the inverse-square law. But the gravitational field is also 100 times less, for the same reason. Because the driving force—radiation pressure—and the opposing force—gravitation—decrease in exactly the same proportion with distance, the net effect does not change with distance. The KBO of the same ATM will also recede at 1 m/yr. In the general 2-body radiant system, expansion velocity does not change with distance.

In summary: a radiant, two-body system expands at a rate that depends on the radiant power of the system, and the “Coupling-Parameter” of the 2nd body, which depends primarily on its area-to-mass ratio. Recession velocity for a given ATM does not change with distance.

[snip]

What is "ATM" (my bold)?

Peter Wilson · #65 (**permalink**) 02-May-2006, 10:29 PM

Sorry. ATM = Area-to-mass ratio

Nereid · #66 (**permalink**) 02-May-2006, 11:48 PM

Quote:

Originally Posted by Peter Wilson

Sorry. ATM = Area-to-mass ratio

Is it the same as "surface-to-mass ratio (STM)"?

If not, then how does it differ?

If so, then why two terms for the same thing?

Peter Wilson · #67 (**permalink**) 02-May-2006, 11:58 PM

Quote:

Originally Posted by Jerry Jensen

Not a good argument - if we understand the SN Ia process:

The example I used is a core-collapse SN. In the core-collapse SN, all of the expansion energy is gravitational. Gravitational contraction supplies the energy of the observed expansion.

Quote:

Another poor example - here, the gravitational assist is exactly akin to tacking a sailboat into the wind. Planets can just as easily be used to provide gravitational braking - I think the Messinger probe uses both Mercury and Venus to help it slow down.

Your counter-example just proves my point, that expansion and contraction always go hand-in-hand. The Messinger probe's orbit contracts, in this case, and the orbits of Mercury and Venus expand. It's the same conservation-of-energy principle: if one part of the system contracts, another part must expand. If you generalize this principle to the universe-at-large, you find that local contraction everywhere must result in cosmic expansion. The universe is expanding because the universe is contracting.

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If you want to argue that gravitational squeezing of matter eventually leads to the release of primal energy in some cases, that may be true, but it is difficult to argue that all bodies that are contracting are causing expansion somewhere else.

It is not an argument, it is an observation, and it is not "primal energy," it is gravitational energy that is released. Consider a mereroid careening through the solar system. As it approaches a body, it loses potential energy (PE), while gaining kinetic energy (KE); as it moves away from a body, it gains potential energy while losing kinetic. The whole time, the total energy (PE + KE) = constant. However, if that meteroid skims earth's atmosphere, then it begins to radiate away energy. That is why you can see it. When it finally falls to earth, all the gravitational energy that it had (wrt earth) has been radiated away. The earth-meteroid system has contracted, while the universe over-all has expanded. Granted, the contribution from one meteor is infinitesimal, but when you sum the contributions from all radiant sources in the universe, it adds up. As I argue in post 60, the total energy radiated away due to gravitational contraction in the universe is far, far greater than the energy taken up by expansion. Gravitational systems lose energy in the form of radiation as they contract, and some of this energy shows up in the expansion of the universe.

bigsplit · #68 (**permalink**) 09-May-2006, 06:40 PM

that dark energy represented over 70% of the total energy of the Universe with dark matter in the 20s and ordinary matter the least. If the local contration (dark matter and ordinary matter) produce the dark energy...it does not add up....or am I missing something?

Peter Wilson · #69 (**permalink**) 10-May-2006, 04:22 PM

It is evident the readers are having some difficulty figuring out just what it is I am trying to say. That is to be expected, because I am talking in a completely different paradigm.

I recently came across a draft of the idea I wrote in 1987, titled simply, “Why the Universe is Expanding”. Threw it in a drawer and forgot about it. In reading something I’d written nearly 2 decades earlier, I found myself saying a lot: “Huh?” The seed of the idea was there, but the explanation was convoluted and not at all convincing. So I kinda’ know how ya’ll are feeling.

Needless to say, this project to explain why the universe is expanding got side-tracked. I got interested again in 1998 when it was announced that the expansion was accelerating—which I already knew. Then when I got laid off in 2003, and with a lot of spare time, I began to consider in earnest: How in god’s name do I explain this? I’ve tried explaining it six million ways to sideways. I’ve looked at it from every possible angle, plus seven. It’s perfectly clear to me, but I’m still trying to figure out how to explain it to you.

An important first key is to understand the paradigm shift. It is like the shift from the Ptolemaic to the Copernican model of the solar system. To understand why the planets move in the sky the way they do, you have to abandon the in-born notion that the earth is stationary. And to understand the expansion of the universe, you have to abandon the idea that has been fixed in mainstream for eight decades: the explanation for expansion is to be found in the past. The mainstream has been barking up the wrong tree, because the answer lies in the present.

The explanation for the expansion of the moon’s orbit is in the present: the earth is spinning. The explanation for the expansion of the sun is in the present: nuclear reactions are taking place in its core. The explanation for the expansion of the universe lies in the ever present: the universe is contracting.

And when trying to follow the math, keep in mind that in an infinite universe, the amount of energy and matter is infinite, so you cannot do a “total.” You can only talk about “energy-per-unit-something.” In my accounting, I do the math in joules-per-kilogram. The mainstream uses energy-per-volume, which is equivalent to energy-per-mass, so long as you include the density. My approach may be unfamiliar, but it is more intuitive and straight-forward. Energy-per-unit-mass is less confusing than energy-per-unit-volume-at-such-and-such-density. So make the switch.

Quote:

Originally Posted by bigsplit

I thought that dark energy represented over 70% of the total energy of the Universe with dark matter in the 20s and ordinary matter the least. If the local contraction (dark matter and ordinary matter) produce the dark energy...it does not add up....or am I missing something?

No, you’re right. This is where it gets confusing, because I have no idea where the mainstream gets their numbers. In my estimate (post 60), the observed radiant energy is many, many OOMs greater than the energy required to produce the observed expansion (instead of OOMs less). In other words, in my estimate it does add up! Which is my point. The expansion makes perfect sense, and is to be expected, based on the observed contraction, without any additional energy besides that given up by local contraction. There is dark and light matter, radiation, local contraction, and cosmic expansion. It all adds up.

Quote:

Originally Posted by north

i agree to a point, but; the thing is though is that both can cause the opposite to happen. it depends on position of both relative to each other. explain further. i'm not quite sure what you mean.

Well, you’ve nearly explained it yourself. Its reciprocity, like the yin-yang principle, like the wave-particle duality, like north-and-south. You cannot have one without the other; cannot have contraction without expansion.

Quote:

Originally Posted by andyschlei

This implies action at a distance. The two skaters only spin faster as they move together because they are holding on to each other. There is no innate connection between largely separated bodies…

Well, you’re “almost right.” There is a connection…a very, very, very weak gravitational connection. And that is why it takes so little energy to expand it! (According to my estimates, anyway.) That is why I cannot figure out how the mainstream gets their IMMENSE(!) expansion energy. Your comment drives right to the heart of what I’m trying to say: the “connection” between remote objects is “almost zero.” There’s very little force between objects 5 megaparsecs apart! It takes very little energy to overcome it.

Quote:

Originally Posted by Nereid

And if you work with Newtonian physics, you can write down equations, showing that A = B; observational data can be plugged in, and indeed A = B.

Okay, let A = energy radiated by matter undergoing local gravitational contraction; let B = gravitational energy gained by matter due to the expansion. If A explains B (as I’m contending), then A > B (as bigsplit points out).

In post 33, I estimate A to be 1 j/kg/yr; in post 60, I estimate B to be < 10^(-20) j/kg/yr (almost zero, as andyschlei would have it). I have explained both of these estimates to the best of my abilities. If I’ve lost you somewhere or made a mistake (you already found one, thanks), please say specifically where in post 33 or 60, and we’ll go from there.

Nereid · #70 (**permalink**) 10-May-2006, 06:37 PM

Quote:

Originally Posted by Peter Wilson

The expansion estimate will just about wrap up the present presentation of DEILE. In one sentence: The on-going expansion of the universe on cosmic scales is a natural, to-be-expected consequence of the on-going contraction occurring on local scales.
[snip]

Consider that the expansion of the moon’s orbit is driven by the spinning earth. [snip]

The earth-moon system is a two-body affair, of course, while the expansion of the universe involves an infinite number of bodies. The calculation is a little more difficult. This is where the “tensor-matrix algebra” comes in, I believe. Nonetheless, the two-body system and the infinite-body system share some characteristics, which we can use to get a feel for the answer.

First, in both the two-body system and the infinite-body universe, the rate of expansion determines the power. [snip]

Secondly, the power of expansion for both the two-body system and infinite-body universe depends on the density. [snip]

Lastly, recall that the starting assumption for the two-body system is that the 2nd body is in a stable orbit around the 1st, and we are considering only the rate-of-change. [snip]

We now look at how a radiant two-body system behaves. Take the solar-system. Technically, it’s a multi-body system, but for the OOM est., the two-body model is a good approximation. The power output of the sun is roughly 4 x 10^26 watts (post 33). This radiation produces a net outward force of about 70 trillion pounds. But how “efficiently” does this 70 trillion lb-f of outward pressure “couple” to the two-body system under consideration?

The efficiency of coupling, or coupling-parameter (CP), depends on the albedo of the 2nd body, and its surface-to-mass ratio (for larger than molecular-scale systems). [snip]

What this means is that sub-micron dust gets “coupled” efficiently to the solar wind and expanded right out of the solar system on the order of years (think comet tails); 10-micron-sized dust gets expelled on the order of centuries; 100um dust is driven out in millennia, etc. For a Jupiter-sized body, however, the sun will burn out before expelling it. The point is, the sun has plenty of expansion energy available, but the “coupling” of this energy to bodies in orbit is very small, except for the very smallest.

[snip]

In summary: a radiant, two-body system expands at a rate that depends on the radiant power of the system, and the “Coupling-Parameter” of the 2nd body, which depends primarily on its area-to-mass ratio. Recession velocity for a given STM does not change with distance.

[snip]

As to the effect of distance: In the two-body radiant system, we saw that expansion velocity is constant with distance. When you go from 2-bodies in 2-dimensions, to an infinite number in 3-dimensions, the expansion velocity increases with distance, instead of remaining constant. When you add one dimension, velocity multiplies by one dimension. Another way to look at it is to picture the 3D infinite system as a bunch of 2-body systems “added up.” So instead of recession velocity being constant, it keeps “adding up,” that is, it increases with distance. In other words, Hubble’s law: expansion proportional to distance.

As noted above, expansion energy is proportional to density. The density of the universe is about 3 x 10^-27 kg/m^3. source The density of earth-moon system is about 0.1 kg/m^3. The earth-moon system is expanding at roughly 100 ppt/yr, “the same” OOM as the universe. The universe is 26 OOMs less dense than the earth-moon system, however. Making a wild guess, I would say the expansion energy of the universe at-large is 26 OOMs less than in the energy involved in the earth-moon system, i.e. about 10^(-29) j/kg/yr.

This seems impossibly small.

But when I look at the numbers, it seems the answer must be very small, whatever it is. The density of the universe is said to be something like 1 hydrogen atom per cubic meter. Over the course of a year, the distance between each atom increases from 1.0m to 1.000000000073m. How much force is there between hydrogen atoms 1 meter apart? How much energy can it take to move them apart by 10^-10 per year? It has to be a small number, whatever it is.

Summarizing the parameters that are known with confidence:
1) Expansion rate of universe: 73 ppt/yr
2) Expansion rate of earth-moon system: same OOM as universe
3) Energy of expansion of earth-moon system: <0.001 j/kg/yr
4) Density of earth-moon system: 0.1 kg/m^3
5) Density of universe: 3 x 10^-27 kg/m^3

Maybe my math is off a little.

To hedge, I’ll split the difference. I’ll add 9 OOMs to the energy estimate, and knock 8 OOMs off the CP guess.

Final estimates:

1) Power output, P, of visible matter: 1 j/kg/yr
2) Coupling parameter (CP): 10^(-20)
3) Resulting power of expansion (P*CP): 10^(-20) j/kg/yr
4) Resulting expansion rate, H:10^(-10)/yr

In layman’s terms: Density of the universe is not mathematically zero, but close to it. Expansio rate is almost zero. Energy of expansion is almost zero. Energy available to drive expansion? 1.0 (j/kg/yr). Conclusion? Expansion easily explained in terms of radiant energy available.

According to The Mainstream, however:

1. The expansion energy is immense, and can only be accounted for by dark energy.
2. The quantity of DE required to explain the expansion is so large it makes up 74% of the universe.
3. Radiant energy plays no significant roll in expansion.

How could my back-of-the-envelope calculation be so different?

The infinite-body system is not an exact analog of the two-body system. Maybe energy in the infinite body goes at the square-root of density, instead of linearly. That would bring it up from 10^(-29) to 10^(-15) j/kg/yr. GR complexifies things, and maybe that changes it by an OOM or two. Maybe I have to multiply it by the age of the universe, 10^10 years. That is still only 10^(-3) j/kg. It’s a mystery to me.

When I look at the numbers, everything seems to add up. Thin universe; slowly contracting; expanding even more slowly. Just another ordinary universe. No Inflation. No Dark Energy. No elephant in the chicken coop. :yawn: Just a thin soup—3 x 10^(-27) kg/m^3 thin—on a budget of 1 j/kg/yr, becoming even thinner, at a sub-glacial 10^(-10) per year. Really, not much happening…well, Old-man Rigley died last year.

But the mainstream insists, No, it doesn’t add up. You’ve got the math all wrong, and don’t understand GR. In a 2-body system, sure, radiation pressure causes expansion. But in GR, in an infinite universe, positive pressure produces contraction, not expansion. Here, post 7 Only DE, which produces negative pressure, can overcome the positive pressure of radiation.

According to TM, the universe is crazy. In the beginning, there was this huge explosion. Crazy. But that didn’t work. Bangless BBT So we added inflation. Crazy. But it worked. For a while. Then we found the expansion was accelerating. Crazy. Dark energy was added to explain that, but it takes a lot of it. Crazy. The universe is crazy, and if you think otherwise…

I don’t know. Maybe it is. The expansion seems rational to me. 73 ppt/yr? It’s like almost nothing is happening. What is wrong with this picture? I can’t tell. I’ve gone over the numbers again and again. Extremely thin universe; contracting locally at a moderate clip; radiating energy as it does so; resulting in infinitesimal expansion over-all. Looks right on paper. Everything appears in order, exactly as it should be. All I can say in conclusion is that if TM is right on all this, and the universe is crazy after all…at least I got something to blame it on!

There seem to be a number of confusing aspects to this presentation, due to the analogies used (well, confusing to me anyway):

-> the increasing size of the Moon's orbit: I can't see how this relates to the expansion of the universe. The driver (for the Moon) is angular momentum and the difference between the rotation period of the Earth (1 day) and the revolution period of the Moon (1 month); the coupling is a function of the properties of the Earth - its radius, the size of the Moon-induced tides, etc. If the Earth were rotating more slowly than the Moon is orbiting (say, once a decade), then the Moon would be spiralling in.

-> solar system bodies: only very small objects are blown out of the solar system by the Sun's radiation pressure; the rest will eventually spiral in to the Sun, due to the Poynting-Roberton effect (it's more complicated than this - there's also the Yarkovsky effect, for example). How does this illustrate DEILE? If we're going to work with analogies, at the very least it shows the importance of considering rotation, and (more generally) the complexity of calculating radiation pressure induced motion (there will always be motion transverse to direction of the radiation, and Poynting-Robertson type effects must be at least considered).

So where does DEILE stand? Even without looking for other shortcomings (than just some simple considerations of other effects of 'radiation pressure'), I'd say there's at least a great deal more work to be done.

Peter Wilson · #71 (**permalink**) 10-May-2006, 11:57 PM

Quote:

Originally Posted by Nereid

There seem to be a number of confusing aspects to this presentation, due to the analogies used (well, confusing to me anyway):

-> the increasing size of the Moon's orbit: I can't see how this relates to the expansion of the universe.

The earth-moon sytem is a reference point. It is expanding at the same rate as the universe. And because there is conversion factor between foot-pounds and joules, it is easy to convert its expansion energy into joules/kg/yr.

Quote:

-> solar system bodies: only very small objects are blown out of the solar system by the Sun's radiation pressure; the rest will eventually spiral in to the Sun, due to the Poynting-Roberton effect (it's more complicated than this - there's also the Yarkovsky effect, for example).

This is an oft repeated misconception. Like on an airplane, there are lift-forces to consider, and drag forces. Radiation pressure produces the equivalent of lift, and the PR effect produces drag. The net effect, however, is lift, or expansion. You can cite a counter-example, a body spinning in a certain way, for exmple, that spirals in, but the net effect is always expansion. Comet tails aways point away from the sun. This is not an analogy, but erosion/sedimentation is. You can find erosion and sedimentation occuring all over the earth, but above sea-level, the net effect is erosion, and below sea-level, the net effect is sedimentation. In like manner, the net effect of solar radiation pressure is expansion.

Quote:

Originally Posted by Nereid

So where does DEILE stand? Even without looking for other shortcomings (than just some simple considerations of other effects of 'radiation pressure'), I'd say there's at least a great deal more work to be done

Follow the energy. I'm on vacation thru the 15th, so the discussion will have to wait for awhile. But in the mean time, consider this: The universe has a density of 3 x 10^(-27) kg/m^3; it is expanding at a rate of 10^(-10)/yr.

How much energy can it take to expand something with such a low density at such a low rate? It is expanding at the same rate as the earth-moon system, but it is roughly 25 OOMs less dense. How much energy can that take?

Nereid · #72 (**permalink**) 11-May-2006, 05:09 PM

Quote:

Originally Posted by Peter Wilson

The earth-moon sytem is a reference point.

A "reference point" for what?

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It is expanding at the same rate as the universe.

It is?
Has it always?
So what?

Quote:

And because there is conversion factor between foot-pounds and joules, it is easy to convert its expansion energy into joules/kg/yr.

So?

Quote:

Originally Posted by Nereid

-> solar system bodies: only very small objects are blown out of the solar system by the Sun's radiation pressure; the rest will eventually spiral in to the Sun, due to the Poynting-Roberton effect (it's more complicated than this - there's also the Yarkovsky effect, for example).

This is an oft repeated misconception. Like on an airplane, there are lift-forces to consider, and drag forces. Radiation pressure produces the equivalent of lift, and the PR effect produces drag. The net effect, however, is lift, or expansion.

More (confusing) analogies.

In the case of bodies in the solar system, above a certain size, the net effect is (nearly always) in-spiralling.

For real objects, these effects are quite real - you can't turn one off and leave another on, at your whim.

Quote:

You can cite a counter-example, a body spinning in a certain way, for exmple, that spirals in, but the net effect is always expansion. Comet tails aways point away from the sun.

They do indeeed ... and dust streams abound in the solar system (producing meteor showers), the particles responsible for zodiacal light are spiralling in to the Sun, ...

But, since you made the claim ("the net effect is always expansion"), let's see you defend it - show that the net effect is always expansion.

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This is not an analogy, but erosion/sedimentation is. You can find erosion and sedimentation occuring all over the earth, but above sea-level, the net effect is erosion, and below sea-level, the net effect is sedimentation. In like manner, the net effect of solar radiation pressure is expansion.

Quote:

So where does DEILE stand? Even without looking for other shortcomings (than just some simple considerations of other effects of 'radiation pressure'), I'd say there's at least a great deal more work to be done

Follow the energy. I'm on vacation thru the 15th, so the discussion will have to wait for awhile. But in the mean time, consider this: The universe has a density of 3 x 10^(-27) kg/m^3; it is expanding at a rate of 10^(-10)/yr.

How much energy can it take to expand something with such a low density at such a low rate? It is expanding at the same rate as the earth-moon system, but it is roughly 25 OOMs less dense. How much energy can that take?

OK, we'll wait until you're back.

If you read this before you go, perhaps you could consider this:
- the orbit of Phobos is decaying (it's inspiralling, not expanding)
- binary pulsars are in orbits that are decaying (not expanding)
- China's energy production is expanding at a much faster rate than the universe is expanding.

Perhaps the causes of China's expanding energy production have as much to do with the expansion of the universe as changes in the Moon's orbit?

Peter Wilson · #73 (**permalink**) 17-May-2006, 09:37 PM

Quote:

Originally Posted by nereid

A "reference point" for what? … Has it always? So what?… So?

Good! Good! Now I can begin to see where I’m losing you.

What I’m trying to do with the moon analogy is to put the Hubble expansion in perspective. In the popular image, the universe is “flying apart.” But in reality, the universe is expanding at an infinitesimal rate…slower than the moon’s orbit is expanding. And everyone understands that the moon is not “rushing away.” Likewise, remote galaxies are not “rushing away.” Yes, the distance between remote objects is increasing, but so what? The distance between them is already immense.

Nothing is going anywhere.

All that is happening is the distance between remote things is increasing. Associated with this increase in distance is an increase in energy. It takes so-much energy to increase the distance between the earth and the moon, at the observed rate of expansion of 10^(-10)/yr. And it takes so-much energy to increase the distance between remote objects (> 5 Mpc) at the observed rate, which for an OOM estimate is the same 10^(-10)/yr.

As for the foot-pounds…again, I’m trying to put the expansion/contraction into familiar terms. What is one joule? What is 1 j/kg/yr? Think of something weighing about 1 kilo; now imagine lifting it 2”. You have imparted 1 joule of energy to it. Now you "know" how much energy 1 joule is. Lower the kilo back down, and you have “a feel” for how much energy is lost in proportion to mass each year. So by expressing the expansion energy in terms of elevation-change-at-earth’s-surface, we can get “a feel” for the energy involved that is intuitive. The intent of all this information is not to confuse, but to help the reader "get the picture."

And the earth-moon analogy is not intended to show that all orbiting bodies spiral away, but simply to make the point that expansion points to an energy flow. Since the earth spins faster than the moon orbits, energy flows from the earth to the moon. The expansion is rotational energy transmogrifying into gravitational energy. The expansion of the universe is likewise: gravitational energy is flowing from local to non-local regions, carried by radiation, and manifested as increasing distance between things.

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More (confusing) analogies. In the case of bodies in the solar system, above a certain size, the net effect is (nearly always) in-spiraling. For real objects, these effects are quite real - you can't turn one off and leave another on, at your whim…Show that the net effect is always expansion.

I’m not turning off the drag effect by whim. The drag effect of light only applies in a stationary radiation field (read the wikipedia entry carefully). The sun’s radiation field is not stationary. It rotates at 1 rpm (month…not minute

). Most solar system objects have a rotation rate much slower, so the radiation field is transferring angular momentum to the particles, not the other way around. Very close to the sun, orbiting bodies will orbit faster than the radiation field rotates, and hence will transfer momentum to the field, and spiral in to their doom.

I am arguing that it is not particle size that determines “spirality,” but instead it is rotational velocity of the orbiting body wrt the rotational velocity of the radiating body. Nonetheless, let us not get side-tracked debating when and when not particles spiral in or out. We both agree there is "a line." On one side of the line is contraction; on the other is expansion. You’re arguing that in the solar system “the line” is particle size; I’m arguing that “the line” is radial velocity. But we both agree that there is a line.

We’ll assume you’re correct, for the sake of argument, that “dust” (what we see in comet tails) spirals away from the sun, but that larger particles spiral in. If so, it’s just another example of the contraction/expansion motif that I keep hammering on. Earth satellites below geosynchronous orbit spiral in; above, they spiral away. “Hot” globs of gas expand; “cold” globs of gas contract. Massive stars in a globular cluster tend to “sink” towards the center; less-massive stars tend to “float” away. Virtually all gravitational systems have inflection points, “a line,” of one kind or another, with contraction on one side, and expansion on the other: size; temperature; spin; distance…whatever. With regard to the universe over-all, “the line” is distance. There is net contraction below 5 Mpc; net expansion beyond it.

The energy of expansion beyond 5 Mpc is much less than the energy of contraction generated within 5 Mpc, so Hubble the expansion is not a mystery at all, but a natural and to-be-expected phenomenon.

Peter Wilson · #74 (**permalink**) 18-May-2006, 09:14 PM

In calculating the energy of expansion of a given system, there are 3 basic variables: expansion rate, density and configuration. Calculating the expansion energy of the earth-moon system is trivial (answer= 10^(-4) j/kg/yr, see post 60) and since the rate is the same as the universe over-all, we use the 10^(-4) j/kg/yr expansion energy of the earth-moon (EM) system as a “reference point” to get rid of one variable, the expansion rate.

Next we consider density. If the density of the EM were halved, that is if each body weighed half as much, the force between them would be halved, and the energy-per kilogram would be halved, given the same rate of expansion. Applying this same principle: if the density of the EM was 25 OOMs less, then the expansion energy would 25 OOMs less. What we would be left with is something like a dust mote being orbited by an even smaller dust mote, 250,000 miles away. Intuitively, the expansion energy of such a system is very, very small. Specifically, such a 2-body system, with the same density as the universe, and expanding at the same rate, would have an energy of expansion of some 10^(-29) j/kg/yr.

Last, we consider configuration. The EM is 2-body, 2-dimensional system, and the universe is an infinite-body,3D fractal affair. So how do you compare an apple to an orange? Admittedly, this math lies over my head, but by getting rid of 2 variables—rate and density—we are down to just 1 variable: configuration. Obviously, it takes more energy to expand an infinite-body 3D system at a given rate-and-density than a 2-body system of the same parameters, but it is not infinitely more. It is just some factor, call it X, that comes out in the math. You multiply the 10^(-29) j/kg/yr by X, whatever it is, and you get the expansion energy of the universe. And 10^(-29) j/kg/yr multiplied by almost anything is a still a small number.

The expansion rate of the universe is very small: 10^(-10)/yr. The density of the universe is extremely small: 10^(-27) kg/m^3. Just looking at these two numbers, it seems the expansion energy must be very small.

Does this clarify why I believe the expansion energy of the universe is so small? Can anyone explain how the mainstream comes up with an expansion energy that is so huge?