The BB and energy

[barbos]

Yeah, "loss of energy" is very common yet incorrect expression. More physically correct expression would have been "Loss of work" or "loss of free energy" but "free energy" while legitimate thermodynamical function has very different and non-physical connotation in laymen's world.

 

[atrib]

Heat transfer is often modeled as an electric circuit.

I think here's where you went wrong. You're taking this analogy too far, thinking that as electric circuits are less than 100% efficient, so must heat transfer be.

There's one important aspect in which heat transfer is nothing like an electric circuit or any other kind of energy transfer or transform, and the hot keyphrase that should alarm us is the word heat.

Heat is what happens as the side product of any less-than-100% efficient energy transfer. If storing energy in pumped hydro is only about 90% percent efficient, it's because 10% of the energy is "used" to heat up the turbines and the pipes due to friction. If synthesising fuels to burn them at peak times is only about 35% efficient, it's because 65% is "used" to heat up the facilities at both stages, though mostly at the burning stage (ever wondered why thermoelectric plants require coolant water?). So worrying about efficiency when what's transferred is heat and we don't care where it's transferred to makes no sense. We can define it as anything between 0% and 100% efficient, and all those values yield the correct result: 100% of the energy transferred comes out as heat.

I think you are making my point, is radiative cooling to cosmic background equilibrium a lossless process?

Lossless in what framework? The object loses energy as it radiates it heat and its particles slow down. Surrounding space gains energy through the same process, and its temperature increases slightly locally, in the short term. The process of cooling simply transforms energy from a low entropy state (hot body that can do useful work like heating water to make tea) to a higher entropy state that cannot.

Ultimately, everything in the universe is powered by the initial conditions at the Big Bang i.e. the delicate, finely tuned low entropy state of the early universe allows work to be done to create complex structures like stars and living things, which will decay away given enough time due to the arrow of time and what Mr. Boltzman said. Nature apparently does not like gradients in mass and energy density, and will ultimately turn everything into nothing, an unimaginably long time away in the future.

 

[atrib]

Thanks for the responses. I do not have the energy or eyes to jump into cosmology where the answer for me would be. I'll leave it here.

Watch videos on youtube. Seriously. Especially if its late and you are having trouble falling asleep.

 

[steve_bank]

I think you are making my point, is radiative cooling to cosmic background equilibrium a lossless process?

Lossless in what framework? The object loses energy as it radiates it heat and its particles slow down. Surrounding space gains energy through the same process, and its temperature increases slightly locally, in the short term. The process of cooling simply transforms energy from a low entropy state (hot body that can do useful work like heating water to make tea) to a higher entropy state that cannot.

Ultimately, everything in the universe is powered by the initial conditions at the Big Bang i.e. the delicate, finely tuned low entropy state of the early universe allows work to be done to create complex structures like stars and living things, which will decay away given enough time due to the arrow of time and what Mr. Boltzman said. Nature apparently does not like gradients in mass and energy density, and will ultimately turn everything into nothing, an unimaginably long time away in the future.

BB does not start at t(0), it does not explain the initial conditions.

 

[steve_bank]

I am well versed in applying thermodynamics. LOT applies to a bounded system. Consider an audio amp. It is delivering 100 watts to the air through a speaker. The power at the mains input will be 100 watts plus loses in the system. Within the amp there will be energy that can not be used or recovered to do useful work in the system. Waste heat goes to the mass surrounding the amp via conduction, convection, and radiation.

You said it yourself: waste heat. If total energy in any transfer or transform is preserved, even is some is lost as heat, how do you think you can meaningfully even ask whether heat transfer is lossless?

A thermodynamic boundary or system can be Earth-sun or solar system-galaxy. The problem with entropy is when the boundary is the universe. If entropy applies to the universe then processes inevitably run down due to increasing entropy.

How is that a problem?

Applying LOT is about where the system boundary is set. A system defined as an object in space radiates and receives energy proportional to temperature difference to the background. Simple analysis. There is no possible system boundary to encompass background as an isolated source of heat. LOT can not be applied.

How does that follow?

My view is that in an infinite universe total energy can not decrease or increase, only form changes. It is what makes sense to me.

It didn't make sense to you yesterday. Also, you're about 200 years late to figuring this out.

How does it follow?

LOT evolved in the 18th century from experiments and observation with steam engines and heat transfer, not cosmology. . LOT applies to a system with a defined boundary.

Consider an audio amp driving a speaker. Heat is the result of losses in the transistors. I can put a thermopile on heatsinks, boost the voltage to the power supply and the recovered energy can be used to do work driving speakers. Due to efficiencies all of the waste heat generated can not be recovered in the system to do work. In any bounded thermodynamic system there is energy that can not be used to do work in the system. In an audio amp all energy in the end shows up as heat in the environment. Speaker moving air raises air temp and so on.

On the scale of the universe energy is not lost and that leads into cosmology. There is no way to experimentally test LOT on a cosmic scale. If the universe is bounded and finite then issues arise.

Occam's Razor for me precludes something from and to nothing. What makes sense is an infinite universe. In an infinite universe with no beginning and end initial conditions apply only locally in a bounded system.

In radiative heat transfer in space there will be a loss. That loss has to show up somewhere.

 

[Jobar]

Put an object in deep space which has been cooled down close to absolute zero. It will warm up- until it reaches equilibrium with the 3.2K cosmic background radiation.

A warmer object will cool down to that temperature.

 

[steve_bank]

Put an object in deep space which has been cooled down close to absolute zero. It will warm up- until it reaches equilibrium with the 3.2K cosmic background radiation.

A warmer object will cool down to that temperature.

Yes but no energy transfer is loss free, at least so far experimentally here on Earth.

 

[Jobar]

I don't know if this is relevant, but although the universe is still expanding, and the background radiation is slowly cooling, the last time I read anything about it space appears to be perfectly flat- neither open nor closed, gravitationally.

Does that mean the universe can, or can not, be considered a closed system, thermodynamically? The two may not be related, but I'm not sure.

 

[skepticalbip]

Put an object in deep space which has been cooled down close to absolute zero. It will warm up- until it reaches equilibrium with the 3.2K cosmic background radiation.

A warmer object will cool down to that temperature.

Yes but no energy transfer is loss free, at least so far experimentally here on Earth.

You are still looking at this as an engineering problem rather than a physics problem.

It is true that in engineering 100% of the energy applied can not be converted to desired work. Some of the energy applied is "lost" as in not resulting in the work the system is designed to do. That is an engineering principle.

However, the principle in physics is that energy can not be created or destroyed, only converted to a different form or forms. In physics problems, all the applied energy must be accounted for - none is ever "lost". That engineering system that was not 100% efficient accounts for some of the energy budget in the work done but physicists also concern themselves with that part of the energy budget that engineers call "lost". That "lost" bit is generally found to be as heat.

 

[steve_bank]

Put an object in deep space which has been cooled down close to absolute zero. It will warm up- until it reaches equilibrium with the 3.2K cosmic background radiation.

A warmer object will cool down to that temperature.

Yes but no energy transfer is loss free, at least so far experimentally here on Earth.

You are still looking at this as an engineering problem rather than a physics problem.

It is true that in engineering 100% of the energy applied can not be converted to desired work. Some of the energy applied is "lost" as in not resulting in the work the system is designed to do. That is an engineering principle.

However, the principle in physics is that energy can not be created or destroyed, only converted to a different form or forms. In physics problems, all the applied energy must be accounted for - none is ever "lost". That engineering system that was not 100% efficient accounts for some of the energy budget in the work done but physicists also concern themselves with that part of the energy budget that engineers call "lost". That "lost" bit is generally found to be as heat.

Physics problems are no different than engineering problems. Same math same thermodynamics.

Everything must add up. Fission, a chemical reaction, or an audio amp. LOT covers it all. Matter, work and energy is the same in all engineering and science disciplines. SI. The term that describes any matter energy balance is called a continuity equation. Kirchoff's Laws in circuits is a continuity equation expressing LOT. Bernoulli's Equation is a continuity equation. I've been involved in enough science to say there is no fundamental difference between science and engineering. It all reduces to LOT. Your resorting to saying 'engineering view' has no bearing.

The problem as I see it is not fully comprehending what LOT means and the implications.

https://en.wikipedia.org/wiki/Bernoulli's_principle

Bernoulli's principle can be derived from the principle of conservation of energy. This states that, in a steady flow, the sum of all forms of energy in a fluid along a streamline is the same at all points on that streamline.

If you cool an object in deep space below background it will rise to the background. That energy comes from somewhere, energy can not be created or destroyed, form changes... as you said. The background then is cooling i it not?

On the other hand the ISS uses radiative cooling, adding to the background thermal radiation. That leads me to consider the universe itself a perpetual motion machine.

Lot applies to a bounded system with matter/energy input and output, and matter/energy transformation in the boundary.

In a bounded universe LOT does not apply, no inputs and outputs. In an infinite universe LOT does not apply, no boundary. Therefore LOT only directly applies in all 3 laws locally. Local could be a solar system, galaxy, or a refrigerator. You can't just pick conservation of energy.

 

[bilby]

Put an object in deep space which has been cooled down close to absolute zero. It will warm up- until it reaches equilibrium with the 3.2K cosmic background radiation.

A warmer object will cool down to that temperature.

Yes but no energy transfer is loss free, at least so far experimentally here on Earth.

The First Law of Thermodynamics requires that EVERY energy transfer is loss free.

Engineers might refer to energy that cannot be useful to, or contained by, their design as 'lost', but that's just taking a narrow view. The efficiency of an engine cannot be 100%; But the total energy in nevertheless always exactly equals the total energy out.

Some of that energy might leave the system about which the engineer cares, but none leaves the universe, and the physicist cares about the whole universe as a system.

 

[steve_bank]

Put an object in deep space which has been cooled down close to absolute zero. It will warm up- until it reaches equilibrium with the 3.2K cosmic background radiation.

A warmer object will cool down to that temperature.

Yes but no energy transfer is loss free, at least so far experimentally here on Earth.

The First Law of Thermodynamics requires that EVERY energy transfer is loss free.

Engineers might refer to energy that cannot be useful to, or contained by, their design as 'lost', but that's just taking a narrow view. The efficiency of an engine cannot be 100%; But the total energy in nevertheless always exactly equals the total energy out.

Some of that energy might leave the system about which the engineer cares, but none leaves the universe, and the physicist cares about the whole universe as a system.

'Leaving the universe' has no meaning. LOT, all three together , apply to a bounded system with inputs, outputs, and internal processes.

Could be a solar system or a refrigerator. At the level of cosmology and varying definitions of the universe, LOT can not apply. Applying LOT requires inputs, outputs, and doing work. LOT does not directly apply to cosmology.

Again you leaped before looking. LOT evolved in the 19th century from experiment and observation with steam engines.

1st Law always applies, but with qualifications. People tried to make perpetual motion machines based on 1LOT and they couldn't do it. Putting a generator on one end of a shaft and a motor on the other having the generator drive the motor is an electrical example of perpetual motion.

2LOT and 3LOT came about as qualifiers to 1LOT based on experiment. Matter and energy are conserved, but in a system all of the energy cannot be used to do work in the system. Take a look at the Clausius Statement.

The BB does not explain how the initial conditions came to be. BB is a good model, it accounts for all or most of observation today, but it is conjecture and extreme extrapolation back in time. Fitting LOT to cosmology is problematic. If the universe is finite, will it run down? My view is the universe in toto is itself perpetual motion ot infinite in energy.

The question of heat transfer by radiation between the background and an object can potentially be treated as a bounded system. Raising the temp of an object deducts energy from the background, which I believe is cooling. Then the boundary expands to the origins of the background. The boundary increases until it is bounded by a finite universe, or ecpands without limit in an infinite universe. That is my view.

The analysis of where waste heat goes is simple, if you understand LOT fully.

Draw a boundary around the Earth. A solar powered refrigerator creates waste heat. The heat is radiated away or conducted away into the ecosystem. Temperature rises. I'd have to look up the energy balan. . Solar radiation enters and powers the refrigerator. Thermal energy is added to the environment. The environment globally heats up, and some is radiated away into space. I don't know what the net thermal radiation is from Earth. Expand the boundary to the solar system, then the galaxy and so on. Eventually you run into what the bounds of the universe are, and that is what cosmologists think about.

The above is of course a sim-lification of climate science as to how wate energy moves through the ecosystem and what gets radiated away. That is what climatologists think about.

LOT is LOT engineering or science, that is why LOT is the foundation. It describes all workings short of cosmic limitations whatever they may be.

 

[repoman]

This thread

https://physics.stackexchange.com/questions/64226/negative-pressure-counteracting-gravity

has me not knowing up from down

How is negative pressure not a fudge factor? Not seeing how this can happen.

 

[steve_bank]

This thread

https://physics.stackexchange.com/questions/64226/negative-pressure-counteracting-gravity

has me not knowing up from down

How is negative pressure not a fudge factor? Not seeing how this can happen.

My read is this, a false analogy and misuse of terms.

When you compress gas work is done.

You can not compress energy, energy has no independent existence. Energy is the capacity to do work. Coal hcan create heat which can do work. Compressing energy has no meaning.

To me dark matter is a fudge factor a placeholder for an observed effect with an unknown cause. One way to look at constants in science is as fudge factors that make things work mathematically. Nothing wrong with that.

'...conservation does not apply to an expanding universe...' goes to my point, at the level of he universe in toto LOT breaks down among the theories. At that point you can create any mathematical cosmology.

In the case of a bounded region in space be it a star o ra volums with dark matter, I would reject any theory that violated LOT.

All that on dark energy is pure conjecture. An observational discrepancy was found in the BB theory. Dark matter was coined to resolve the discrepancy and properties assigned to it. That is how science works.