Why the sky is dark in the night

[paddoboy]

But from points (1) and (2) there is no trivial discrediting of Big Bang cosmology from conservation of energy arguments. The Big Bang is an empirical fact so, by definition, successful cosmological theories have to explain its empirical basis in detail.

I have two views on this and the reasons why some see the need to dismiss such overwhelmingly supported theory as the BB.
The first reason is that like the otherwise great scientist Fred Hoyle and his compatriots Bondi and Gold, the thought that the Universe had a beginning was too much for them due to the fact that the church could comfortably hang their proverbial hat on that fact as the work of God.
They ignore the fact that while this has proven to be true, it is also just a method of short circuiting science and cosmology at a level where at those times, knowledge is rather scarce, instead of continuing the scientific search via the scientific method:
The other point is the fact that some who [to use your rpenner's terminology] are rather dilettante in their approach to the subject or perhaps have an agenda of sorts, see the fact that the BB, SR/GR, Evolution, with regards to our particle zoo, all compliment each other, which makes their evangelistic missions to try and discredit any aspect of any of the above just that much more difficult.

 

[danshawen]

The Big Bang model says nothing about time (or energy) before the Big Bang.

And therein lies the problem, rpenner.

The only difference between that idea and the Steady State universe is that in the Big Bang model of the universe before the Big Bang has nothing in it for negative eternity.

I don't know of any math that can justify that idea. You cannot posit an eternity without time if you don't understand the first thing about what time actually is, with or without the math. Too bad, because energy doesn't exist without time either. If you can define one without the other, please show us. Even a probability density involves time indirectly.

 

[paddoboy]

And therein lies the problem, rpenner.

No, no problem other than that is just the limit of the theory.

The only difference between that idea and the Steady State universe is that in the Big Bang model of the universe before the Big Bang has nothing in it for negative eternity.

The BB is a model of the Universe/spacetime evolving into what we see today, 13.83 billion years post. We have evidence attesting to that.
We have nothing for the SS hypothetical.
There is absolutely no evidence before t+10-43 seconds after the BB event.
Space and time [spacetime] as we know them, evolved into what we see today.
Before that we can only speculate, so speculate to your heart's content, but don't make silly supposed assumptions as probable fact.
That's why the search is on for a QGT.
There is as much evidence for the SS as there is for Lawrence Krauss's Universe from nothing proposal, or the Universe being the ultimate free lunch.
But these people recognise that they are just in speculative territory.

 

[danshawen]

There is nothing intellectually dishonest about any of the ideas I have submitted in this thread.

I do not derive benefit nor compensation from any activity connected to mainstream cosmology.

There are gaping holes in the mathematical concept of what constitutes a universe big enough to accommodate an infinitude of poorly crafted models. Energy non-conservation doesn't even blemish the surface, much less plumb its depth.

If the universe were illuminated only by what we we actually know about science and or math, it would be much darker than one conceived by anything like Olber's paradox.

 

[danshawen]

I followed rpenner's link to Sean Carroll's blog which I used to read and previously posted to regularly.

http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/

which discusses the latest GR buzz about conservation of energy as applied to BB and inflation:

"... The success of Big Bang Nucleosynthesis depends on the fact that we understand how fast the universe was expanding in the first three minutes, which in turn depends on how fast the energy density is changing. And that energy density is almost all radiation <see how Sean conveniently jettisons GR when appropriate?>, so the fact that energy is not conserved in an expanding universe is absolutely central to getting the predictions of primordial nucleosynthesis correct. (Some of us have even explored the very tight constraints on other possibilities.)

Having said all that, it would be irresponsible of me not to mention that plenty of experts in cosmology or GR would not put it in these terms. We all agree on the science; there are just divergent views on what words to attach to the science. In particular, a lot of folks would want to say “energy is conserved in general relativity, it’s just that you have to include the energy of the gravitational field along with the energy of matter and radiation and so on.” Which seems pretty sensible at face value."

"...Energy isn’t conserved; it changes because spacetime does. See, that wasn’t so hard, was it?"

So for the sake of getting just a few relative inflation and stellar nucleosynthesis abundances right, cosmology is willing to toss out the bedrock principle of conservation of energy? I don't happen to think that is a very wise idea. For one thing, nucleosynthesis is not something that happened or worked itself through to present day abundances IN THE FIRST THREE MINUTES of creation, unless you decide to revert to the superstition that preceded actual science. Elemental abundances generated out of nothing doubtless took a bit longer to cook to their present state than that. If you swallow that, the next thing you will be reading is that evolution happened at a similar frenetic pace, and with no fossil record to support that idea either.

And so when Sean started debating philosophers and creationist religious leaders like William Lane Craig every other week, I stopped reading his blog.

Just when you thought Galileo had it bad, you get science like this.

The defense (of science) rests. Sean has aptly demonstrated all of my central points. When they try to pin you on conservation of energy, you compress the time line of BB/inflation and if that doesn't work, you start talking about the finer points of quantum nucleosynthesis.

Science that does not build on established science isn't science.

 

[rpenner]

Please join me in welcoming rpenner as a new moderator. He will be moderating the Physics & Math and the Astronomy subforums.

rpenner will be an awesome moderator. And I promise to try very hard to take his moderating advice whenever rendered.

Try harder.

Post #71: Unsupported speculation, unconnected to topic as Olber's paradox is already answered prior to speculation.

Question answered in post #72.

Post #73: Baseless call for bound on number of black holes. Ample display of misunderstanding of GW150914 event as something other than the end of a millennium-long dance of astrophysics. Beginning of baseless denialism of Big Bang cosmology, including describing mainstream cosmology and General Relativity as a "fraud" and a "fantasy."

In post #74, DaveC424913 points out that it is baseless to call for a new survey of black holes when there are strong observational bounds on the number of black holes.

In post #75, Billy T suggests that for adequate definition of energy, there may be energy conservation and that conserved quantity may be zero.

In post #76, DaveC424913 points out the sterility of your attempt to re-define science.

In post #77, I point out that there are different viewpoints on conservation of energy in General Relativity, which is partly because it is defined in terms foreign to GR and partly because it is not as fundamental as you advocate. This post could be viewed as an informal warning that you are far removed from a position to convincingly make the claims you have. I also point out that your opinions are not original to you, but are just not nearly as compelling as you believe them to be.

Post #78: You misstate the content of Big Bang cosmology in various ways not supported by appropriate scientific sources, even when sources are supplied for you to learn Big Bang cosmology correctly. You are intellectually dishonest in two distinct ways when you write "E (total, before the Big Bang) = E (total, after the Big Bang)" in that you don't define your terms when I have pointed out that definitions are important and you have ignored Billy T's post #75 in which case both are hypothesized to be zero. You claim energy conservation was arrived at by the scientific method, but ignore that energy non-conservation is empirical fact described daily as "cosmological redshift".

Post #79 is my second attempt to informally warn you that you are well outside any honest argumentation and that you can't deny the empirical basis for Big Bang cosmology just because of some esthetic quibbles. Your misunderstanding of the relation between physical theory and energy conservation law does not rise to the level of those Cambridge quibbles that are the targets of continuing research.

In post #80 DaveC424913 wants to be educated on the status of energy conservation laws in general relativity, a complicated subject for reasons given above.

In post #81, paddoboy suggests that there may be ulterior motives to deny Big Bang cosmology. Indeed, I have known evolution-deniers to deny Big Bang cosmology for very parochial concerns unrelated to the scientific evidence and seen such denialism adopted by the uneducated.

Post #82: You misstate the nature of time in general relativity and ignore the actual content of Big Bang cosmology.

In post #83, paddoboy points out that your discussion of "before" the Big Bang is based on assumptions not part of either Big Bang cosmology or General Relativity.

Post #84: You rebut claims that you have been intellectually dishonest by cherry picking one form of dishonesty. You then appeal to arguments that you have not made or even described. You then pooh-pooh the realms of science and math as unilluminating, which begs the question of your purpose here.

Post #85: Finally, you read one of the pages I linked to and cherry pick it. This is not the "latest GR buzz" as it cites mainstream GR from the 1920's. Sean Carroll, in the very parts you quote, explains that both views expressed in my post #77 are held because the question is one of definitions. You misrepresent this as tossing out a "bedrock principle" but that is only your peculiar and uneducated description. You seem to advocate creationism. You seek to elevate yourself as the judge of what is science.

This you may not do. Since informal warnings have had zero positive effect on the manner of your discourse, I have formally warned you.

 

[rpenner]

False claim: Big Bang cosmology is based on suspending science.
Fact: Big Bang cosmology is based on empirical observations of

• Cosmological expansion
• Cosmic background radiation
• Primordial distribution of light isotopes
• Structure of the universe at large scales

and theoretically based on General Relativity, Astrophysics, Nuclear Physics and Particle Physics which are the best comprehensive theories that cover the relevant phenomena.

False claim: Conservation of Energy is required in any physical theory.
Fact: Untrue. Emmy Noether explained the origin of the conservation of energy as a type of time symmetry that cannot be rectified with General Relativity. Sean Carroll recognizes this but does not find fault with either General Relativity nor Big Bang cosmology because Conservation of Energy is not absolutely required. Energy non-conservation appears in textbook problems based on real systems for real reasons, so it is not per se a problem with physical theories.

False claim: Conservation of Energy is only a problem with Big Bang theory during and prior to the inflationary epoch.
Fact: Untrue. Conservation of Energy is a general problem in General Relativity because there is no general prescription to discuss curved space-time as if it were flat and therefore the meaning of time in general relativity is nothing like the meaning of time in special relativity or Newtonian physics.

False claim: Cosmological expansion was relative to some exterior geometry.
Fact: Neither GR nor Big Bang cosmology was formulated on the basis of embedding the universe in some external geometry.

False claim: Big Bang cosmology is a Steady State cosmology in the present era.
Fact: False. Not only was the Hubble constant first estimated in the present era, but expansion isn't slowing down.

False claim: A Steady State cosmology explains Olber's paradox.
Fact: Since the "paradox" is that the sky is dark when an eternal, infinite, unchanging, homogeneous universe would seem to require a bright sky, nothing is explained by assuming a Steady State cosmology. The finite age of the Big Bang model explains why there more dark than stars. The cosmological expansion explains why the distant stars appear dimmer and cooler and the CMBR is very dim and cool relative to its brightness at time of formation.

False claim: Talking about local conservation of energy is a red herring.
Fact: Since GR posits that all space-time is locally flat, and Noether says time translation symmetry in the laws of physics gives rise to a law of conservation of energy, this is not a red herring but a missed opportunity for danshawen to learn physics.

False claim: There is no room for imagination in science.
Fact: All scientific theories are born in human imaginations. The are vetted in the cold fires of empirical testing, however.

 

[The God]

Fact: Untrue. Conservation of Energy is a general problem in General Relativity because there is no general prescription to discuss curved space-time as if it were flat and therefore the meaning of time in general relativity is nothing like the meaning of time in special relativity or Newtonian physics.

Great efforts....nice posts.

1. So, you admit that conservation of Energy is a problem in GR ?

2. What is the meaning of time in GR ?

For example, whatever we refer as time in day to day Newtonian/life...a flow of time...arrow of time...lapse time...How is it different from GR time.....Generally proper time in GR can be associated with metric, numerically it may differ due infinitesimal curved spacetime around.....but how does it create problem (and survives) with fundamentals of Physics that Energy is conserved ? Your reference to Noether Theorem is problematic in GR, as IMO efforts are there to prove the conservation on some kind of pseudo tensors......

The point I am making, which I feel is relevant is that, there is no place in the universe where curvature is = 0 (it can be --->0), so time asymmetry would be present everywhere, suggeting non conservation of energy in true sense, is thats what you are saying ?

 

[The God]

False claim: Big Bang cosmology is based on suspending science.
Fact: Big Bang cosmology is based on empirical observations of

• Cosmological expansion
• Cosmic background radiation
• Primordial distribution of light isotopes
• Structure of the universe at large scales

and theoretically based on General Relativity, Astrophysics, Nuclear Physics and Particle Physics which are the best comprehensive theories that cover the relevant phenomena.

This structure of universe at large scale which includes mega structures and clusters too ..is dubbed as an issue with BB.

When you refer of structure of universe at large scale, you cannot discard these mega clusters...although I will agree that literature uses simple statement like 'Structure of Universe at large scale' as support for BB, but it is actually not.

 

[The God]

And therein lies the problem, rpenner.

The only difference between that idea and the Steady State universe is that in the Big Bang model of the universe before the Big Bang has nothing in it for negative eternity.

I don't know of any math that can justify that idea. You cannot posit an eternity without time if you don't understand the first thing about what time actually is, with or without the math. Too bad, because energy doesn't exist without time either. If you can define one without the other, please show us. Even a probability density involves time indirectly.

You are right........BB certainly has questions around it about the origin of that so called singularity ? It has questions about inflation....But the great winning point for BB is lack of alternative which can explain the various observations...It is either to remain theoryless or accept BB, the lesser evil for science is to accept BB till....

 

[The God]

Kudos to exchemist and origin for posts #4 & #5.

Praising someone is always good......but in forums where heat can get generated, the Mods should be careful in praising posters...........question the content not the poster..similarly praise the post not the poster, certainly not when putting down some other poster.

It would be nice for someone to do calculations in thread, but since Olber's assumptions of an infinite, static, eternal Euclidean universe are experimentally and observationally disfavored, we must move beyond "why is the sky dark" to "why is the sky as dark as it is in detail" and such details will include Big Bang optical effects causing distant galaxies to be dimmer both by red shift and causing them to take up more angular measure than if the universe weren't expanding.

Lets go with the full moon night...quite ok...not as bright as day but much brighter than star light....

Sun is around 150 million Kms away from Earth/moon....Moon radius is around 1700 Kms....orbital radius of moon is around 384000 Kms......Sun emitts around 10^26 watts......a photon carries around 10^-19 units energy........So the number of photons emitted by Sun per second is around 10^45...........Number of photons as received by moon is around 10^35.....number of reflected photons (from moon) as received by Earth (thus the scattering) is around 10^31....

So when the Earth receives 10^31 photons from moon, the night sky is decently bright............

There are in excess of 10^30 stars in the universe.........(surely we don't see any star of any Galaxy other than MW) still if we receive on an average 10 photons from each star (not a high number).... we should have sky brighter than full Moon night..........The redshift notwithstanding.

More/less angular measure and redshift is less important than finiteness in mainstream explanation...

The God is required to calculate what a redshifted black body curve is and to test if that shifted curve is still a black body curve.

Pray, first tell me what is the original Black Body at the time of BB ?

 

[Farsight]

...False claim: Conservation of Energy is required in any physical theory.
Fact: Untrue. Emmy Noether explained the origin of the conservation of energy as a type of time symmetry that cannot be rectified with General Relativity. Sean Carroll recognizes this but does not find fault with either General Relativity nor Big Bang cosmology because Conservation of Energy is not absolutely required. Energy non-conservation appears in textbook problems based on real systems for real reasons, so it is not per se a problem with physical theories.

What's this, rpenner? If you can offer any example of non-conservation of energy, I'd be interested to hear about it.

 

[danshawen]

My purpose here is to counterpoint paddoboy and brucep's negative and abusive influence, rpenner. I can still feel their influence, even when I ignore them.

"Intellectual dishonesty" is their favorite catchphrase. "Illiterate crank" is a close second. I am neither, nor have I abused anyone one here in that fashion, and as a new moderator, you would be best advised not to do so either. It's the opposite of moderate.

Sean Carroll has noted in the link you provided that non-conservation of energy gives both scientists and laymen pause, and it should. I have thrown in my ring with those.

I am open minded enough to consider the possibility that the BB theory may prove to be substantially correct, even down to the details of nucleosynthesis. But I do not admit to the kind of intellectual dishonesty that motivated the Ptolemists of an earlier era of science, nor the creationists that took their place. On this, like Galileo, I do not yield, even under house arrest by Pope Urban his majesty.

And Sean Carroll was not even as successful at countering creationists as was Bill Nye, to Bill Nye's credit. Somehow, there were no real or clear winners in either debate. Like this one. It was more like the GOP debates in that it settled nothing of any substance that anyone seemed to be really interested in.

GR is not a fraud or a fantasy. I read Sean's GR blog entries and mathematical papers on the subject with great interest and carefully considered the energy non-conservation that is implied by it for a number of years.

Some parts of BB and inflation theory have much to commend them, but providing a central geometrical locus or a time origin where geocentrism and G-d once stood is not the most attractive nor scientific features of either. A universe where time does not yet exist would be a strange location from which to declare: "Let there be light". THINK about it.

 

[The God]

I will have the thread moved to the CT forum where it belongs.
There it will get the treatment it needs.

How will you have ? You are some kind of super cop, who can instruct James / Rpenner ?

Your take, that those scientists cannot be wrong..is the same line mostly taken up by Paddoboy when he is cornered, is bereft of any content.

And by the way what is CT forum ?

 

[The God]

No. I'm not going to put any more effort into other avenues while you continue to ignore the fact that your request for how to address the basic/standard paradox as pertains to Andromeda (given by you in post #10) was fulfilled in post #28:

You need to prove that you actually want to figure Olbers' paradox out and start doing so real work toward that (this should take about 3 minutes), not just keep leading us on argumentative wild goose chases.

I would be delighted to assist you in solving this very relevant and very easy problem *you* proposed, to help you learn why the sky isn't extremely bright. Is that not why you are here?

That said, FYI, all of the questions you asked in post #66 are answered in the wiki article on the CMBR. You should read it and get back to us with your updated understanding.

Quite an angry young man.....sounds more like resident PHD Physbang..

 

[Farsight]

For the record I think Sean Carroll is wrong in multiple ways in this blog post. For example he says this: "And in my experience, saying “there’s energy in the gravitational field, but it’s negative, so it exactly cancels the energy you think is being gained in the matter fields” does not actually increase anyone’s understanding — it just quiets them down". Gravitational field energy is positive, not negative.

 

[rpenner]

The God is required to calculate what a redshifted black body curve is and to test if that shifted curve is still a black body curve.

Please either do this calculation or admit that you cannot.

1. So, you admit that conservation of Energy is a problem in GR ?

Obviously this was a reference to post #77, where I present two physicists' expert summaries of the fact that there are two camps in GR -- (1) those that work out energy conservation schemes where total energy is conserved and (2) those that don't bother as they are only interested in coordinate-independent concepts. If you don't understand Noether's theorem, then you don't understand where energy conservation laws come from. In Newton's Principia Mathematica there is no law of conservation of energy because it was a concept that would come later as the ramifications of the physical theory were explored mathematically. In GR, because space and time are subject to influence, any time translation symmetry is not a trivial one such as in Newtonian mechanics, therefore the definition of the globally conserved quantity in GR may not conform to the definitions of energy used in earlier theories of flat space-time.

2. What is the meaning of time in GR ?

In Newtonian physics, time is an absolute with only the origin undetermined due to a time translation symmetry in the laws of physics. In Special Relativity, coordinate time is a choice of an inertial standard of rest and proper time is a choice of a sub-luminal trajectory through space-time. In General Relativity, coordinate time is an arbitrary smooth choice, and while locally one can use a free-fall standard of rest as the basis for simple local coordinate time, that local coordinate standard can look weird at distant points. Since time in Relativity is not like that of Newtonian theory, it follows that globally conserved energy cannot be simply equated with Newtonian globally conserved energy. Definitions and details are important.

The point I am making, which I feel is relevant is that, there is no place in the universe where curvature is = 0 (it can be --->0), so time asymmetry would be present everywhere, suggeting non conservation of energy in true sense, is thats what you are saying ?

Since you equate energy conservation with Newtonian concepts of global energy conservation which are based on time translation symmetry of a universally applicable absolute time, I'm saying your concept of energy conservation is not applicable to general relativity. You must decide which of the two camps described in post #77 you fall into or leave it as a matter for experts who make understanding GR their profession.

This structure of universe at large scale which includes mega structures and clusters too ..is dubbed as an issue with BB.

Is it? Where, specifically?

The God is required to support all future posts on the this subject of cosmology with citations for each contested factual claim.

I will agree that literature uses simple statement like 'Structure of Universe at large scale' as support for BB, but it is actually not.

Do you mean specific literature or all the literature? How is it not support?
Are we to assume that your OP was part of a dishonest campaign to pose a question you expected to be answered with a mainstream cosmology that you reject?

The God does seem to take great pains to dismiss empirical cosmology while asking a question completely within its bailiwick.

But the great winning point for BB is lack of alternative which can explain the various observations...It is either to remain theoryless or accept BB, the lesser evil for science is to accept BB till....

That's how science is done. Nitpicking doesn't destroy theories, it reveals areas where either better physics instruction or future research needs to be done. What destroys theories are better theories.

You are some kind of super cop, who can instruct James / Rpenner ?

It's my job to be sensitive to petitions which are consistent with the forum rules. Why would I not respond positively to a well-made case that the rules needed to be enforced?

Your take, that those scientists cannot be wrong

How is that the position of DaveC426913? Isn't his position closer to you haven't demonstrated that your position is right?

And by the way what is CT forum ?

From context, a forum suitable for Conspiracy Theories, unsupported claims that groups are trying to hide the truth. We do indeed have a forum dedicated to those that retreat from engagement with humanity in that direction.

Quite an angry young man

Holding you to a minimum standard of self-education when you are the one throwing stones at the entire fields of Cosmology and General Relativity doesn't make one angry. It makes one principled.

What's this, rpenner? If you can offer any example of non-conservation of energy, I'd be interested to hear about it.

In textbook problems, a simple example might be a gas or particle (Newtonian, Quantum, it doesn't matter) in a box that is changing shape (either steadily or periodically). The laws of physics (here the boundary conditions for the physics being considered) no longer have a simple continuous time translation symmetry and energy conservation appears broken. Since assigning equal and opposite energy change to the box when its physics (as a boundary condition) are unknowable seems like a cop out (despite that any physical realization will have knowable physics) the two GR camps would be split into defining a conserved quantity analogous to Newtonian energy or ignoring global energy conservation as inapplicable.

 

[danshawen]

This is a great thread; one of the best IMO.

 

[rpenner]

My purpose here is to counterpoint paddoboy and brucep's negative and abusive influence, rpenner. I can still feel their influence, even when I ignore them.

That's not a valid purpose.

"Intellectual dishonesty" is their favorite catchphrase. "Illiterate crank" is a close second. I am neither, nor have I abused anyone one here in that fashion, and as a new moderator, you would be best advised not to do so either. It's the opposite of moderate.

My job will hurt some people's feelings. Science will hurt some people's feelings. Truth will hurt some people's feelings. Those aren't reasons not to do my job, teach science or pursue truth.

Sean Carroll has noted in the link you provided that non-conservation of energy gives both scientists and laymen pause, and it should. I have thrown in my ring with those.

That's supposed to be a pause for thought. Not an indefinite halt to thinking.

I am open minded enough to consider the possibility that the BB theory may prove to be substantially correct, even down to the details of nucleosynthesis...

I will not praise you on being "open minded" to empirical corroboration — that's the minimum for admittance into the world of scientific discourse. Also, Galileo wasn't threatened with mere house arrest but torture and imprisonment. His sentence was commuted to house arrest.
https://en.wikipedia.org/wiki/Galileo_affair#Trial_and_second_judgment.2C_1633

[Big Bang cosmology provides] a central geometrical locus

Untrue. Your failure to learn to think in General Relativistic terms leaves you thinking about the Big Bang as an explosion into space from a point, when it was an explosion of space without central point. Where a black hole is said to have a time-like singularity extending into the indefinite future, the model of a Big Band has a space-like singularity encompassing all the space there was. In both cases, those singularities represent our ignorance of what really happens/happened, but our physical theories seem to have plenty of validity on this side of those singularities.

A universe where time does not yet exist would be a strange location from which to declare: "Let there be light". THINK about it.

If this was a religion forum, this would leave you open to charges of blasphemy for purporting to put logical limits on God's power. As this is not a religion forum, I would like to point out that this is a physics argument of exceptionally low weight.

 

[Farsight]

In textbook problems, a simple example might be a gas or particle (Newtonian, Quantum, it doesn't matter) in a box that is changing shape (either steadily or periodically). The laws of physics (here the boundary conditions for the physics being considered) no longer have a simple continuous time translation symmetry and energy conservation appears broken. Since assigning equal and opposite energy change to the box when its physics (as a boundary condition) are unknowable seems like a cop out (despite that any physical realization will have knowable physics) the two GR camps would be split into defining a conserved quantity analogous to Newtonian energy or ignoring global energy conservation as inapplicable.

Can you offer any example where energy conservation is definitely broken as opposed to appears broken?

I note your remark above: "I'm saying your concept of energy conservation is not applicable to general relativity. You must decide which of the two camps described in post #77 you fall into or leave it as a matter for experts who make understanding GR their profession". See what I said above about gravitational field energy being positive rather than negative.