No Big Bang. Other than your head exploding...

[asdfjkl]

phys.org/news/2015-02-big-quantum-equation-universe.html

You can't C&P the whole article.  But the long and short of it is: the universe had no beginning.  It has always existed.  

Here's the beginning of it:

(Phys.org) —The universe may have existed forever, according to a new model that applies quantum correction terms to complement Einstein’s theory of general relativity. The model may also account for dark matter and dark energy, resolving multiple problems at once.

The widely accepted age of the universe, as estimated by general relativity, is 13.8 billion years. In the beginning, everything in existence is thought to have occupied a single infinitely dense point, or singularity. Only after this point began to expand in a “Big Bang” did the universe officially begin.

Although the Big Bang singularity arises directly and unavoidably from the mathematics of general relativity, some scientists see it as problematic because the math can explain only what happened immediately after—not at or before—the singularity.

“The Big Bang singularity is the most serious problem of general relativity because the laws of physics appear to break down there,” Ahmed Farag Ali at Benha University and the Zewail City of Science and Technology, both in Egypt, told Phys.org.

Ali and coauthor Saurya Das at the University of Lethbridge in Alberta, Canada, have shown in a paper published in Physics Letters B that the Big Bang singularity can be resolved by their new model in which the universe has no beginning and no end.

Old ideas revisited

The physicists emphasize that their quantum correction terms are not applied ad hoc in an attempt to specifically eliminate the Big Bang singularity. Their work is based on ideas by the theoretical physicist David Bohm, who is also known for his contributions to the philosophy of physics. Starting in the 1950s, Bohm explored replacing classical geodesics (the shortest path between two points on a curved surface) with quantum trajectories.

[NewOrleans]

So incredibly cool. I am hoping someone can explain to me like I am 5 about dark energy.

[asdfjkl]

Aug 21, 2015 10:50:50 GMT -5 NewOrleans said:

So incredibly cool. I am hoping someone can explain to me like I am 5 about dark energy.

I bought a book that is basically "relativity and quantum mechanics for dummies" and it's over my head.  

I will never understand this stuff.  I try to read these articles and I hope like 4 or 5 sentences make sense to me so that I get the general point.  Like here, "The universe had no beginning."  Why?  Don't know.  How?  Not sure.  What existed before the matter in the universe existed?  I'm sorry, I don't understand the question.

[sangria]

I'm gonna go stare into my co-worker's eyes for 10 min.

My pea brain can't even grasp this.

[asdfjkl]

Aug 21, 2015 10:58:17 GMT -5 @majorwife said:

Aug 21, 2015 10:56:17 GMT -5 asdfjkl said:

I bought a book that is basically "relativity and quantum mechanics for dummies" and it's over my head.  

I will never understand this stuff.  I try to read these articles and I hope like 4 or 5 sentences make sense to me so that I get the general point.  Like here, "The universe had no beginning."  Why?  Don't know.  How?  Not sure.  What existed before the matter in the universe existed?  I'm sorry, I don't understand the question.

try explaining the internet to ants. 

that's what we are man. we are just ants in the grand scheme of things.

I'm reading a book right now where the author proposes the idea that our own brains aren't capable of understanding WHAT we are and that as an organism we might not be the kind of animal capable of understanding what we are.  Like our brains won't ever be powerful enough to even ask the right questions, much less contemplate and reach a correct answer.  He uses deafness as an example.  So, there are people who can't hear.  And they have no way of every knowing what it really means "to hear."  They don't know what it is "to hear." What would it be like "to hear?"  Our existence is the same way.  We do not have the faculties, "the organs" to know what we are.  The same way a deaf person doesn't know what "to hear" is.  Or a blind person doesn't know what "to look" is.  

[NewOrleans]

Where poetry and quantum astrophysics meet, in honor of National Poetry Day,


The Universe
By May Swenson

What

is it about,

the universe,

the universe about us stretching out?

We, within our brains,

within it,

think

we must unspin

the laws that spin it.

We think why

because we think

because.

Because we think,

we think

the universe about us.



But does it think,

the universe?

Then what about?

About us?

If not,

must there be cause

in the universe?

Must it have laws?

And what

if the universe

is not about us?

Then what?

What

is it about?

And what

about us?

[mbcdefg]

[SallyJ]

Aug 21, 2015 10:50:50 GMT -5 NewOrleans said:

So incredibly cool. I am hoping someone can explain to me like I am 5 about dark energy.

There something out there that has gravitational effects on other things in the universe. Scientists know this because lots of math (they can't actually see this something). That something is called dark matter.

[NewOrleans]

Aug 21, 2015 11:24:16 GMT -5 SallyJ said:

Aug 21, 2015 10:50:50 GMT -5 NewOrleans said:

So incredibly cool. I am hoping someone can explain to me like I am 5 about dark energy.

There something out there that has gravitational effects on other things in the universe. Scientists know this because lots of math (they can't actually see this something). That something is called dark matter.

This sounds just like black holes, yes? nursecramer?

also, I just watched Interstellar last weekend, so this thread is timely.

[asdfjkl]

Aug 21, 2015 11:23:24 GMT -5 nursecramer said:

Aug 21, 2015 10:50:50 GMT -5 NewOrleans said:

So incredibly cool. I am hoping someone can explain to me like I am 5 about dark energy.

Not in physics, astronomy, or cosmology, but I'll take a shot.

One of the jobs of science is to explain the why and how of the stuff we observe. One way science does this is to create models (aka theories*). Scientists generally express these models in math. The cool thing is that the models not only explains what we see, they also make some predictions. If you do this, you should find this. And models need to be consistent with each other.
Most of our current models work pretty well to explain what we observe and have made some pretty cool predictions that have been confirmed. But some models have gaps, or are inconsistent with each other. Areas where predictions break down, observations that don't quite make sense.

For example, if (using the equations that come from the currently accepted model) you measure the trajectory of a star (which is being pulled by the gravity of other stars) and it should be x, but it's not, it's y. Now the pull gravity is based on two things, mass and distance and we're pretty good at measuring distances. So there must be an issue with the mass. Why does it do this? Nobody has come up with a great way to adjust the equations or the entire model, and the current simplest way to explain these inconsistencies is that there must be some extra mass that we just can't observe and call it "dark mass". The really weird thing is that MOST OF THE UNIVERSE is dark matter and dark energy. So a lot of researchers (like the guy in this article) are working on taking measurements, tweaking equations, or developing new models to try to explain this.


*In science, the word theory means something different than in every day parlance. Most people take theory to mean "a guess" or "an uncertain idea". In science, a theory is a very robust explanation for a phenomenon that is supported by many many many years of scientific research and evidence. A theory not only provides an explanation, but it has made predictions which turn out to be true. And there is no "proving" a theory or graduating it into a law. Theories are explanations of how and why. Laws are descriptions of what. They both require rigorous testing and mountains of evidence, but they answer different types of scientific questions.

So dark energy, dark matter, and dark mass (which are all separate things, right) are things that we can't see, but that must exist in order for our equations to make sense?  

I'm going to ask a kindergarten level question here: instead of hypothesizing an "invisible substance", why don't we just abandon the equation?  Like, if I had hypothesized that 2 oranges and 4 applies would give me 5 pieces of fruit, and then I count them and realize they give me 6, I would not assume there was "dark fruit."  I would assume my understanding of the value of either 2 or 4 was wrong.

[SallyJ]

Aug 21, 2015 11:27:05 GMT -5 NewOrleans said:

Aug 21, 2015 11:24:16 GMT -5 SallyJ said:

There something out there that has gravitational effects on other things in the universe. Scientists know this because lots of math (they can't actually see this something). That something is called dark matter.

This sounds just like black holes, yes? nursecramer?

also, I just watched Interstellar last weekend, so this thread is timely.

Black holes are sort of related.  So much matter (real matter, not dark matter, but maybe also dark matter) is squeezed into such a small space (i.e. smaller than a pin of head) that it has a huge gravitational force and pulls everything toward it.

Dark matter is just there between stars and planets messing up the math for scientists.  It's the 'correction factor' in the equation.

[SallyJ]

Aug 21, 2015 11:28:25 GMT -5 asdfjkl said:

Aug 21, 2015 11:23:24 GMT -5 nursecramer said:

Not in physics, astronomy, or cosmology, but I'll take a shot.

One of the jobs of science is to explain the why and how of the stuff we observe. One way science does this is to create models (aka theories*). Scientists generally express these models in math. The cool thing is that the models not only explains what we see, they also make some predictions. If you do this, you should find this. And models need to be consistent with each other.
Most of our current models work pretty well to explain what we observe and have made some pretty cool predictions that have been confirmed. But some models have gaps, or are inconsistent with each other. Areas where predictions break down, observations that don't quite make sense.

For example, if (using the equations that come from the currently accepted model) you measure the trajectory of a star (which is being pulled by the gravity of other stars) and it should be x, but it's not, it's y. Now the pull gravity is based on two things, mass and distance and we're pretty good at measuring distances. So there must be an issue with the mass. Why does it do this? Nobody has come up with a great way to adjust the equations or the entire model, and the current simplest way to explain these inconsistencies is that there must be some extra mass that we just can't observe and call it "dark mass". The really weird thing is that MOST OF THE UNIVERSE is dark matter and dark energy. So a lot of researchers (like the guy in this article) are working on taking measurements, tweaking equations, or developing new models to try to explain this.


*In science, the word theory means something different than in every day parlance. Most people take theory to mean "a guess" or "an uncertain idea". In science, a theory is a very robust explanation for a phenomenon that is supported by many many many years of scientific research and evidence. A theory not only provides an explanation, but it has made predictions which turn out to be true. And there is no "proving" a theory or graduating it into a law. Theories are explanations of how and why. Laws are descriptions of what. They both require rigorous testing and mountains of evidence, but they answer different types of scientific questions.

So dark energy, dark matter, and dark mass (which are all separate things, right) are things that we can't see, but that must exist in order for our equations to make sense?  

I'm going to ask a kindergarten level question here: instead of hypothesizing an "invisible substance", why don't we just abandon the equation?  Like, if I had hypothesized that 2 oranges and 4 applies would give me 5 pieces of fruit, and then I count them and realize they give me 6, I would not assume there was "dark fruit."  I would assume my understanding of the value of either 2 or 4 was wrong.

Think of it more like 2 and 4 are right because that lines up with all the math in the world, but the answer you get is still 5.  Dark fruit is the correction factor to make the answer 5.

[asdfjkl]

Aug 21, 2015 11:31:43 GMT -5 SallyJ said:

Aug 21, 2015 11:28:25 GMT -5 asdfjkl said:

So dark energy, dark matter, and dark mass (which are all separate things, right) are things that we can't see, but that must exist in order for our equations to make sense?  

I'm going to ask a kindergarten level question here: instead of hypothesizing an "invisible substance", why don't we just abandon the equation?  Like, if I had hypothesized that 2 oranges and 4 applies would give me 5 pieces of fruit, and then I count them and realize they give me 6, I would not assume there was "dark fruit."  I would assume my understanding of the value of either 2 or 4 was wrong.

Think of it more like 2 and 4 are right because that lines up with all the math in the world, but the answer you get is still 5.  Dark fruit is the correction factor to make the answer 5.

I don't like this.  It feels like "because God" to me.  And I'm religious and believe in God, but it still bothers me.  The math/theory breaks down so I, SCIENTIST, dub the gap "dark X".  Ta-da.  Now it makes sense.  

[sangria]

Aug 21, 2015 11:31:43 GMT -5 SallyJ said:

Aug 21, 2015 11:28:25 GMT -5 asdfjkl said:

So dark energy, dark matter, and dark mass (which are all separate things, right) are things that we can't see, but that must exist in order for our equations to make sense?  

I'm going to ask a kindergarten level question here: instead of hypothesizing an "invisible substance", why don't we just abandon the equation?  Like, if I had hypothesized that 2 oranges and 4 applies would give me 5 pieces of fruit, and then I count them and realize they give me 6, I would not assume there was "dark fruit."  I would assume my understanding of the value of either 2 or 4 was wrong.

Think of it more like 2 and 4 are right because that lines up with all the math in the world, but the answer you get is still 5.  Dark fruit is the correction factor to make the answer 5.

OMG I feel like I'm getting dumber by the second! lol 

[mouse]

But everything is still getting further apart, right? That's been observed (I think).

So if we're not continuously expanding because of the Big Bang still throwing us further out forever, what are we observing?

[asdfjkl]

Aug 21, 2015 11:35:56 GMT -5 nursecramer said:

Aug 21, 2015 11:28:25 GMT -5 asdfjkl said:

So dark energy, dark matter, and dark mass (which are all separate things, right) are things that we can't see, but that must exist in order for our equations to make sense?  

YES.

I'm going to ask a kindergarten level question here: instead of hypothesizing an "invisible substance", why don't we just abandon the equation?  Like, if I had hypothesized that 2 oranges and 4 applies would give me 5 pieces of fruit, and then I count them and realize they give me 6, I would not assume there was "dark fruit."  I would assume my understanding of the value of either 2 or 4 was wrong.
Fortunately (unfortunately?) the equations work well for solving many other problems. We can send a space probe to Pluto, we can find planets 500 light years away. At any given time, you have researchers using the current model to make new discoveries and researchers exploring new different models. When those new different models start to be more productive, there will be a shift away from the old model. So if your counting system always works for just oranges, and always works for just apples, you would keep using it for oranges and apples while simultaneously trying out new ways to count them together.

Isn't this sort of like when you're trying to solve the rubix cube, and you have all but 4 of the squares right and you're like "Fuck it!" and rip off the stickers and put them in the right place and are like, "There, I fucking solved it!"

[eponinepontmercy]

Aug 21, 2015 11:25:43 GMT -5 @koko said:

This thread is making me want to go smoke a joint. And I don't even smoke, man.

We're going to need more golden oreos than usual.  And cheetos.

[asdfjkl]

I swear I'm not trying to be difficult or dismissive.  I find this stuff fascinating and the extent to which it is over my head requires me to turn to humor (perhaps even dark humor) to fill the gap between what I an sincerely interested in and what I am capable of understanding.  

[aurora]

Aug 21, 2015 11:36:32 GMT -5 asdfjkl said:

Aug 21, 2015 11:31:43 GMT -5 SallyJ said:

Think of it more like 2 and 4 are right because that lines up with all the math in the world, but the answer you get is still 5.  Dark fruit is the correction factor to make the answer 5.

I don't like this.  It feels like "because God" to me.  And I'm religious and believe in God, but it still bothers me.  The math/theory breaks down so I, SCIENTIST, dub the gap "dark X".  Ta-da.  Now it makes sense.  

Well, it's not quite like that, because the mathematical theories are so complex that it's as though we always had 2 + 4 + x = 5 + y, where x and y are admittedly unknown variables because we always knew we couldn't count the apples and oranges perfectly in the first place.

Think back to the earth-centric view of the universe that prevailed until the 1500s (or so? I can't remember the exact dates). We could explain a lot of things by saying the sun, moon, planets, and stars orbited around the earth, but as we got better at other observations we realized we couldn't explain everything that way. So, we had to completely rethink the "equation" and put the sun at the center of our solar system and have the earth both rotate on its axis and orbit the sun. Everything we already observed still made sense, and other things made even more sense. So, we were missing part of the equation previously. Dark matter is a possible explanation that makes more modern observations make more sense.

It's possible that someday we'll realize we were wrong about dark matter and that there are other theories out there, but we don't have a better one at the moment.

[SallyJ]

Aug 21, 2015 11:36:32 GMT -5 asdfjkl said:

Aug 21, 2015 11:31:43 GMT -5 SallyJ said:

Think of it more like 2 and 4 are right because that lines up with all the math in the world, but the answer you get is still 5.  Dark fruit is the correction factor to make the answer 5.

I don't like this.  It feels like "because God" to me.  And I'm religious and believe in God, but it still bothers me.  The math/theory breaks down so I, SCIENTIST, dub the gap "dark X".  Ta-da.  Now it makes sense.  

Completely agree with you.  Mathematicians and scientists do this all the time...um, the math should work, but doesn't, so add a correction factor and now it works!  Then they spend time trying to figure out what exactly the correction factor is, what the units are, and what the new math equation should be.  

It's why scientists and mathematicians have struggled with the big bang theory.  It requires this concept of dark matter and dark energy (aka correction factor) to make the math work, but the math doesn't describe what those things are, only that they must exist for the equation to work.  And then the math quit working at the absolute beginning of the universe.  From what I'm gathering from this article the new equation now describes dark energy mathematically and accounts for dark energy in the equation (so, 4 + 2 - 1 = 5, where 1 is dark fruit), and because there is no absolute beginning the equation always works.  Or in other words there is a dark matter constant, similar to a gravitational constant.

When I had to take quantum physics in college, my brain hurt so bad.  I can't explain the math exactly, only the 'like I'm 5' and only on some things.

ETA:  And I'm purposely using dark energy, dark matter, and dark mass interchangeably, because for the purposes of 'like I'm 5' they are the same from a simple mathematical standpoint--they are correction factors/constants to make the equations work.  Plus you know the whole mass = energy, and matter has mass thing.  If I was a quantum physicist, these would not be the same thing and should not be used interchangeably.

[LadySusan]

Aug 21, 2015 11:27:05 GMT -5 NewOrleans said:

Aug 21, 2015 11:24:16 GMT -5 SallyJ said:

There something out there that has gravitational effects on other things in the universe. Scientists know this because lots of math (they can't actually see this something). That something is called dark matter.

This sounds just like black holes, yes? nursecramer?

also, I just watched Interstellar last weekend, so this thread is timely.

I think it is different from black holes in that we know a lot about black holes and how they work.  Black holes were confusing at first but then we realized that they emit x-rays so we can see them now that we know what we are looking for.  We are relatively comfortable with black holes.

Dark energy is way more hand wavy.  A placeholder.  I'm going to try to explain but I'm just a biology person.  Scientists know that a + b +c = 100.  They can measure a and and b and they expected c to be zero but it wasn't.  They checked their math a few times and decided to name the phenomenon "dark" matter and "dark" energy.  And now they spend a lot of time trying to figure out what sorts of particles make up this stuff and how it works.

ETA: x-rays

[josieposy]

Aug 21, 2015 11:41:52 GMT -5 mouse said:

But everything is still getting further apart, right? That's been observed (I think).

So if we're not continuously expanding because of the Big Bang still throwing us further out forever, what are we observing?

The galaxies all found each other on Ashley Madison.

[pixy0stix]

[asdfjkl]

Aug 21, 2015 11:54:25 GMT -5 aurora said:

Aug 21, 2015 11:36:32 GMT -5 asdfjkl said:

I don't like this.  It feels like "because God" to me.  And I'm religious and believe in God, but it still bothers me.  The math/theory breaks down so I, SCIENTIST, dub the gap "dark X".  Ta-da.  Now it makes sense.  

Well, it's not quite like that, because the mathematical theories are so complex that it's as though we always had 2 + 4 + x = 5 + y, where x and y are admittedly unknown variables because we always knew we couldn't count the apples and oranges perfectly in the first place.

Think back to the earth-centric view of the universe that prevailed until the 1500s (or so? I can't remember the exact dates). We could explain a lot of things by saying the sun, moon, planets, and stars orbited around the earth, but as we got better at other observations we realized we couldn't explain everything that way. So, we had to completely rethink the "equation" and put the sun at the center of our solar system and have the earth both rotate on its axis and orbit the sun. Everything we already observed still made sense, and other things made even more sense. So, we were missing part of the equation previously. Dark matter is a possible explanation that makes more modern observations make more sense.

It's possible that someday we'll realize we were wrong about dark matter and that there are other theories out there, but we don't have a better one at the moment.

So taking this example though, the problem with the earth-centric view of the solar system was that the foundational principle was wrong.  We created all this "bad math" just so we could keep the earth at the center and then finally, it was like, "Okay, we're going to have to go back to step one: something else might be at the center."  So my question is still sort of, is "dark matter" really a thing, or is it what we're using so we can (analogously) keep the earth at the center.  I'm obviously not thinking about this as a scientist, much less a physicist.  I know this is a really very unsophisticated question, but why are scientists so wedded to this idea of dark X?  It seems like we've been in this situation before in terms of the history of science - where our theories break down, and we always start by trying to create an even more complex theory with some additional X entity that can reconcile it.  And then 100 or 1000 years later it's like, "Oooookaaaaay, we got the fucking first step wrong."  

This isn't devil's advocate, I'm just keeping the conversation going because it's interesting to me.  So I guess I would say my question is, is anyone out there positing that the actual central foundational principles of this are wrong, and what do they suggest is the alternative?  That would interest me.  What's on the other side of this debate?

[asdfjkl]

Aug 21, 2015 12:05:21 GMT -5 josieposy said:

Aug 21, 2015 11:41:52 GMT -5 mouse said:

But everything is still getting further apart, right? That's been observed (I think).

So if we're not continuously expanding because of the Big Bang still throwing us further out forever, what are we observing?

The galaxies all found each other on Ashley Madison.

Which is why there are no answers.  We've asked the universe and it keeps saying, "That wasn't me; I wasn't there.  Must be dark matter.  That asshole's always up to no good."

[aurora]

Aug 21, 2015 12:06:42 GMT -5 asdfjkl said:

Aug 21, 2015 11:54:25 GMT -5 aurora said:

Well, it's not quite like that, because the mathematical theories are so complex that it's as though we always had 2 + 4 + x = 5 + y, where x and y are admittedly unknown variables because we always knew we couldn't count the apples and oranges perfectly in the first place.

Think back to the earth-centric view of the universe that prevailed until the 1500s (or so? I can't remember the exact dates). We could explain a lot of things by saying the sun, moon, planets, and stars orbited around the earth, but as we got better at other observations we realized we couldn't explain everything that way. So, we had to completely rethink the "equation" and put the sun at the center of our solar system and have the earth both rotate on its axis and orbit the sun. Everything we already observed still made sense, and other things made even more sense. So, we were missing part of the equation previously. Dark matter is a possible explanation that makes more modern observations make more sense.

It's possible that someday we'll realize we were wrong about dark matter and that there are other theories out there, but we don't have a better one at the moment.

So taking this example though, the problem with the earth-centric view of the solar system was that the foundational principle was wrong.  We created all this "bad math" just so we could keep the earth at the center and then finally, it was like, "Okay, we're going to have to go back to step one: something else might be at the center."  So my question is still sort of, is "dark matter" really a thing, or is it what we're using so we can (analogously) keep the earth at the center.  I'm obviously not thinking about this as a scientist, much less a physicist.  I know this is a really very unsophisticated question, but why are scientists so wedded to this idea of dark X?  It seems like we've been in this situation before in terms of the history of science - where our theories break down, and we always start by trying to create an even more complex theory with some additional X entity that can reconcile it.  And then 100 or 1000 years later it's like, "Oooookaaaaay, we got the fucking first step wrong."  

This isn't devil's advocate, I'm just keeping the conversation going because it's interesting to me.  So I guess I would say my question is, is anyone out there positing that the actual central foundational principles of this are wrong, and what do they suggest is the alternative?  That would interest me.  What's on the other side of this debate?

I'm also not a physicist, so take all my responses with a grain of salt. But, in my understanding scientists aren't "so wedded" to the idea of dark matter. It's more of a "well, huh, observations aren't matching predictions. What are the possible explanations?" and one of the possible explanations is that there is matter we haven't yet observed, so we wonder "can we find some of that matter?" But there are other possible explanations, including that our foundational equations aren't right for some bigger reason. It's a lot easier to try to think of ways to find dark matter than to go back to the drawing board completely, so I think that's why a lot of people are looking into it as a possible answer right now.

[ttt]

I'm going to go with "we'll never be able to understand this, so let's just go have a drink and write some poetry."

[sangria]

The reason the equations don't work is because the universe is a hologram.

We are the SIMS for someone else.

[downtoearth]

I heard this on NPR earlier and thought about posting, but I didn't quite understand it myself, so I wasn't sure what to think of it. I wonder what my kids will learn about the universe start/beginning now... I'm guessing something totally different than we did in the 80's/90's.

[SallyJ]

So let me see if I can condense these various articles to a couple of simple points:

-Big Bang Theory equations don't work at points of singularity, i.e. beginning of universe. Requires something called dark matter/energy/mass and still mathematically doesn't work at beginning. Scientists also can't explain the 'before the beginning' with any math.

-New theories have suggested Big Bounce with endless loop where it universe expands and collapses on itself. Math still can't explain the point of singularity and requires dark matter/energy/mass to work. Also opens thoughts to alternative universes.

-Newer theories say instead of the equations describing lines that cross each other into points of singularity (i.e. beginnings and ends of the universe or Big Bounce Theory), the equations now describes lines that never cross each other and go on forever and ever (no beginning, no end). There is no dark stuff, but rather a cosomological constant term and a radiation constant term are in the equation. There is also something called a graviton, a gravity particle that controls gravity and has no mass. This means that all of the empty space between other particles be filled with quantum fluid. So maybe the scientists, including Newton were right about the concept of Aether.