# 4th dimension is extension of 3rd dimension. A world within worlds

Question:
If a shadow is a volume of space. Do shadows have mass?.....
No

Write4U said:
Question: If a shadow is a volume of space. Do shadows have mass?.....
But if there is a volume of space with an absence of light, would that not affect the density of that volume in some way?

For one thing there is an absence of photons throughout the entire shadow cone, except for some ambient light refracted from the illuminated sides.

No difference in temperature, expansion, humdity, ???

But if there is a volume of space with an absence of light, would that not affect the density of that volume in some way?

For one thing there is an absence of photons throughout the entire shadow cone, except for some ambient light refracted from the illuminated sides.

No difference in temperature, expansion, humdity, ???

What the above has to do with a shadow being 3D I have no idea

Density - slight increase
Temperature - slight decrease
Expansion - ?
Humidity - ?
Earth magnetic field - same
Earth gravity field - same
Neutrinos - no change
UFOs - remain at zero

A volume is by definition a property of a 3D object, no....
What are some examples of volume?
Volume is the quantity of three-dimensional space occupied by a liquid, solid, or gas. Common units used to express volume include liters, cubic meters, gallons, milliliters, teaspoons, and ounces, though many other units exist. Jan 27, 2020

Think about this. The idea is not as unique as it sounds. A shadow is a local phenomenon which has a different density as the adjacent lighted area?

A volume is by definition a property of a 3D object, no....

Think about this. The idea is not as unique as it sounds. A shadow is a local phenomenon which has a different density as the adjacent lighted area?

I'm thinking but my 3 neurone brain Huwey Dewey and Louie are failing to see what point you are trying to make

The density of a adjacent area (same dimensions and volume) would be minute and would depend greatly on temperature and heat exchange between the two regions

A vacuum also has 3D defined area

I'm thinking but my 3 neurone brain Huwey Dewey and Louie are failing to see what point you are trying to make

The density of a adjacent area (same dimensions and volume) would be minute and would depend greatly on temperature and heat exchange between the two regions
A vacuum also has 3D defined area
Sorry, let me try to explain my perspective.

Consider the moon for a moment. The difference in temperature of the lit (light cone) side and the dark (shadow cone) side of the moon is about + 300 degrees Celsius

260 degrees Fahrenheit
During a full moon, however, the "dark side" is truly dark. Scientists estimate that the far side of the moon gets as hot as 260 degrees Fahrenheit (127 Celsius) during the day, and negative 297 (minus 183 Celsius) during the lunar night. Jan 15, 2019
China's Chang'e-4 to take the far side of the moon's ...

Clearly anything within the shadow cone of the moon will exhibit the absence of solar warmth, in how many possible ways?

Will the Solar Eclipse Have an Impact on the Weather?
BY DENNIS MERSEREAU
JULY 21, 2017
Studies have shown that the total eclipse could also have an effect on temperatures and even winds. Researchers who studied an eclipse across Europe in 1999 found that the event lowered air temperatures by as much as 5°F across the path of totality.

https://www.mentalfloss.com/article/502885/will-solar-eclipse-have-impact-weather

Does a shadow cause all objects within the cone to gain density and mass?

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Clearly anything within the shadow cone of the moon will feel the absence of solar warmth.

Clearly yes. Noted in solar eclipses. Shadow of the Moon moves over the Earth and if you happen to be in the shadow you notice a slight drop in temperature

Clearly yes. Noted in solar eclipses. Shadow of the Moon moves over the Earth and if you happen to be in the shadow you notice a slight drop in temperature

A 2D plane has no volume, it is a slice of the cone.
OTOH , a 3D shadow cone does have "volume" and everything within the volume of the cone is affected in some very specific ways different from the lit part of the surrounding space, including the 2D projection of the shadow. It's cool in the shade...everywhere...

You lie in the sun a few hours and you get sunburn. Lie in the shade and you can spend all day on the beach.

IMO, the volume of a shadow has a real effect on the physical objects inside its cone.......[[[[]]]]....

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But if there is a volume of space with an absence of light, would that not affect the density of that volume in some way?

For one thing there is an absence of photons throughout the entire shadow cone, except for some ambient light refracted from the illuminated sides.

No difference in temperature, expansion, humdity, ???
You would still have the CMBR and you would still have radiation from the object casting the shadow, unless that object were at absolute zero - which is impossible. So even in shadow there is always radiation.

A 2D plane has no volume, it is a slice of the cone

A slice of the cone would be 3D

As per a slice of bread

Insert something in the shadow, ie between light source and original surface where the light was originally finished, you create a shorter shadow, still 3D, between the light source and new inserted object

Depending on numerous factors what you finish up with from the new inserted object to the original surface, where originally the light finished, I will let you calculate

Good luck

You would still have the CMBR and you would still have radiation from the object casting the shadow, unless that object were at absolute zero - which is impossible. So even in shadow there is always radiation.
I am not disputing that. In fact I stipulated that.
My impression was that within the shadow cone, conditions are different than in the adjacent lighted areas. I don't think that was an unreasonable assumption......

Hence my question if inside the shadow cone, spacetime is denser than when the obstruction is removed and that volume of spacetime is not "in the shadow".

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Write4U said:
A 2D plane has no volume, it is a slice of the cone
A slice of the cone would be 3D
As per a slice of bread
Let me clarify. The cast shadow on a surface is a 2d plane. The entire shadow cone represent a 3d volume. Is that better?

I am not disputing that. In fact I stipulated that.
My impression was that within the shadow cone, conditions are different than in the adjacent lighted areas. I don't think that was an unreasonable assumption......

Hence my question if inside the shadow cone, spacetime is denser than when the obstruction is removed and that volume of spacetime is not "in the shadow".
OK, so you are asking what difference to the "density" of spacetime it makes if there is a lower intensity of radiation in one volume of space than in another.

First of all spacetime is not space, and with this business involving shadows you are talking about space. Space has no mass and therefore no density. Radiation has no rest mass either, so no density - unless you mean density of the radiation rather than mass, in which case the answer is obvious.

I have no idea whether it means anything to talk about a density of spacetime. The term does not seem applicable, but I don't pretend to know my way around general relativity.

OK, so you are asking what difference to the "density" of spacetime it makes if there is a lower intensity of radiation in one volume of space than in another.
No, not necessarily radiation, but it seems to me that space behaves differently when cold than when warm, no?
First of all spacetime is not space, and with this business involving shadows you are talking about space. Space has no mass and therefore no density. Radiation has no rest mass either, so no density - unless you mean density of the radiation rather than mass, in which case the answer is obvious.
Space has no mass? No dark matter, no dark energy?
I have no idea whether it means anything to talk about a density of spacetime. The term does not seem applicable, but I don't pretend to know my way around general relativity.
I am not necessarily disagreeing with you, but it seems to me that space has defined properties and that these properties (whatever they are) of space are affected by temperature.

How do you define space?
Space is the boundless three-dimensional extent in which objects and events have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime.
en.wikipedia.org › wiki › Space

Does empty space have mass?
Each cubic centimeter of empty space contains about 10-29 grams of invisible matter, or, equivalently, vacuum energy. This is almost nothing, 29 orders of magnitude smaller than the mass of matter in a cubic centimeter of water, 5 orders of magnitude smaller than the proton mass.
https://www.edge.org/response-detail/26727

However, it seems that space is not massless. Hence the question stands; "does temperature affect the fabric and behavior of spacetime"?

No, not necessarily radiation, but it seems to me that space behaves differently when cold than when warm, no?
Temperature is a property of collective matter; space in-and-of-itself cannot - by definition, have temperature.

Unfortunately, as is your habit, you will use weasel words to argue - using a word in one form to mean one thing and then another form to mean another thing.

Space has no mass? No dark matter, no dark energy?
So, to be clear: space - in-and-of itself - as distinct from the matter that populates it - has no mass, no matter, no temperature, no dark matter.

If you forego the sloppiness of usage of terms, you will find the world makes a lot more sense - and so do you.

No, not necessarily radiation, but it seems to me that space behaves differently when cold than when warm, no?
Space has no mass? No dark matter, no dark energy?
I am not necessarily disagreeing with you, but it seems to me that space has defined properties and that these properties (whatever they are) of space are affected by temperature.

How do you define space? en.wikipedia.org › wiki › Space

Does empty space have mass? https://www.edge.org/response-detail/26727

However, it seems that space is not massless. Hence the question stands; "does temperature affect the fabric and behavior of spacetime"?
Yes, that's right - no.

Space does NOT behave differently when "cold" than when "hot" for the reason Dave gives: it can't be either hot or cold. Without matter, there is no temperature. And by definition "space" means a total absence of matter.

Space has no "defined properties", so far as I am aware, apart from the values of its dielectric permittivity and magnetic permeability.

Dark matter is nothing to do with space. If it exists, it is matter, not space.

Dark energy is a placeholder: we have no idea what it is, if it exists. It's just a fudge factor to make the equations come out right, so far.

Yes, that's right - no.
Space does NOT behave differently when "cold" than when "hot" for the reason Dave gives: it can't be either hot or cold. Without matter, there is no temperature. And by definition "space" means a total absence of matter.
Well that could be one of my arguments, but that does not seem to be the case.
If vacuum energy is so small, how do we even know that it is there? Just try to put 10-29 grams on a most sensitive scale, at it will show nothing at all. At first, many people were skeptical about it, but then combined efforts of cosmologists who studied cosmic microwave background radiation and large scale structure of the universe not only confirmed this discovery, but allowed to measure energy density of vacuum with a few percent accuracy. Doubts and disbelief were replaced by acceptance, enthusiasm, and, finally, by the Nobel Prizes received in 2011 by Saul Perlmutter, Brian Schmidt and Adam Riess.

https://www.edge.org/response-detail/26727

Apparently you are not correct in stating that space has a NO measurable properties.
Space has no "defined properties", so far as I am aware, apart from the values of its dielectric permittivity and magnetic permeability.
Space as defined in science seems to have defined properties. See above.
Dark matter is nothing to do with space. If it exists, it is matter, not space.
Apparently you are wrong in a scientific sense.
Dark energy is a placeholder: we have no idea what it is, if it exists. It's just a fudge factor to make the equations come out right, so far.
So mainstream science has no clue as to what they're talking about? OK.....

Temperature is a property of collective matter; space in-and-of-itself cannot - by definition, have temperature.
Fudging!
Unfortunately, as is your habit, you will use weasel words to argue - using a word in one form to mean one thing and then another form to mean another thing.
The pot calling the kettle black. Fudging.
So, to be clear: space - in-and-of itself - as distinct from the matter that populates it - has no mass, no matter, no temperature, no dark matter.
Wow, they awarded a Nobel prize for "nothing" ?
If you forego the sloppiness of usage of terms, you will find the world makes a lot more sense - and so do you.
Actually, the world makes perfect sense to me. Mathematically speaking, everything has an inherent "value" or "potential". If not, it cannot exist.

Apparently the universe does not make sense to you! I can't do anything about that.......

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Well that could be one of my arguments, but that does not seem to be the case.
The CMBR at 2.73 K is the temperature of space...the relic, left over heat of the BB itself.
Apparently you are not correct in stating that space has a NO measurable properties.
Space as defined in science seems to have defined properties. See above.
The most obvious property of space is that it expands. It is also a variable quantity linked with time.
Apparently you are wrong in a scientific sense.
DM certainly is matter, that lacks the properties we see in normal baryonic matter.
So mainstream science has no clue as to what they're talking about? OK.....
DE makes up about 70% of the universe...fairly substantial, and while we do not know much about it, it does appear to be a property of space, like the CC.
Space is variable...time is variable, but spacetime is invariant.

The following article gives some information and thoughts and facts with regards to the energy/density of space.
http://math.ucr.edu/home/baez/vacuu...asurements that have,9 joules per cubic meter.
extract:
"So, when you ask about the energy density of the vacuum, you get different answers depending on whether the person answering you is basing their answer on general relativity or quantum field theory. Let me run through the 5 most common answers, explaining how people reach these different answers:

1. We can measure the energy density of the vacuum through astronomical observations that determine the curvature of spacetime. All the measurements that have been done agree that the energy density is VERY CLOSE TO ZERO. In terms of mass density, its absolute value is less than 10-26 kilograms per cubic meter. In terms of energy density, this is about 10-9 joules per cubic meter.
One can know something is very close to zero without knowing whether it is positive, negative or zero. For a long time that's how it was with the cosmological constant. But, recent measurements by the Wilkinson Microwave Anisotropy Probe and many other experiments seem to be converging on a positive cosmological constant, equal to roughly 7 × 10-27 kilograms per cubic meter. This corresponds to a positive energy density of about 6 × 10-10 joules per cubic meter.

The reason they get a positive energy density is very interesting. Thanks to the redshifts of distant galaxies and quasars, we've known for a long time that the universe is expanding. The new data shows something surprising: this expansion is speeding up. Ordinary matter can only make the expansion slow down, since gravity attracts - at least for ordinary matter.

What can possibly make the expansion speed up, then? Well, general relativity says that if the vacuum has energy density, it must also have pressure! In fact, it must have a pressure equal to exactly -1 times its energy density, in units where the speed of light and Newton's gravitational constant equal 1. Positive energy density makes the expansion of the universe tend to slow down... but negative pressure makes the expansion tend to speed up.

More precisely, the rate at which the expansion of the universe accelerates is proportional to

- ρ - 3P
where ρ is the energy density and P is the pressure. (This isn't supposed to be obvious: there's a nontrivial calculation involved, and I'm just telling you the final result. The 3 is there because there are 3 dimensions of space, oddly enough.)

But as I mentioned, for the vacuum the pressure is minus the energy density: P = -ρ. So, the rate at which the vacuum makes the expansion of the universe accelerate is proportional to

2 ρ
From this, it follows that if the vacuum has positive energy density, the expansion of the universe will tend to speed up! This is what people see. And, vacuum energy is currently the most plausible explanation known for what's going on.

Of course, to believe this argument at all, one must have some confidence in general relativity. To believe scientists' attempts to determine an actual value for the energy density of spacetime, one must have more confidence in general relativity, and also other assumptions about cosmology. However, the basic fact that the energy density of spacetime is very close to zero is almost unarguable: for it to be false, general relativity would have to be very wrong."

Well that could be one of my arguments, but that does not seem to be the case.
https://www.edge.org/response-detail/26727

Apparently you are not correct in stating that space has a NO measurable properties.
Space as defined in science seems to have defined properties. See above.
Apparently you are wrong in a scientific sense.
So mainstream science has no clue as to what they're talking about? OK.....

What I'm telling you is what mainstream science says, to the best of my knowledge.

I repeat, nobody has any clue at all what "dark energy" may be: it is a just a placeholder label for something not understood.

I also repeat that space has no temperature, because it contains no matter, as Dave said.

Now, on the point about whether the vacuum has an energy density (as opposed to spacetime having a density, which is what you asked earlier), this is contentious and unresolved. Theory suggest there may be a non-zero vacuum energy, but there are hugely conflicting ways of estimating it and no observational evidence to resolve this. Linde, who you quote, takes one view but I do not believe it is accurate to represent his view as that of "mainstream science". The Nobel Prize referred to was for the observational evidence of accelerating expansion of the universe, hence confirming the need for the placeholder of "dark energy". It was NOT awarded for any observations about vacuum energy. Linking the two seems to make sense, but remains conjecture unsupported by observation.

(By the way, since any vacuum energy is zero point energy, it can't contribute to temperature).

Now, before you go off and trawl the internet for more stuff which you hope will contradict what I have said, I should tell you that I am getting bored with this game.

Any further reply I make will depend on how interesting I find it to respond. I have no interest in playing tennis for the sake of it, especially with someone who doesn't think or argue straight.