Ask any question you want about Physics

This thread trespasses into the philosophical here and there.

a reply to: ErosA433

DUDE !!!

YES! I'm off topic here on this thread because I'm not asking but telling...
NO! I will not make my own thread here on ATS !

You appear to absolutely not understand at all what the detection actually looks like on a phenomenological level

"Phenomenological description is a method of phenomenology. A phenomenological description attempts to depict the structure of first person lived experience, rather than theoretically explain it."

NO ! I'm definitely not on that level... and never will be

its an interesting statement, not only disproven by countless experimentation and observation, but also is impossible to use to produce what we actually see in something like a vertex detector.

"A semiconductor detector in ionising radiation detection physics is a device that uses a semiconductor (usually silicon or germanium) to measure the effect of incident charged particles or photons."
"Ionizing radiation is radiation that carries enough energy to detach electrons from atoms or molecules, thereby ionizing them. Ionizing radiation is made up of energetic subatomic particles, ions or atoms moving at high speeds (usually greater than 1% of the speed of light), and electromagnetic waves on the high-energy end of the electromagnetic spectrum."

...as I told you, EM kicking electrons out of mater

hell even a spark chamber disproves it.

"A spark chamber is a particle detector: a device used in particle physics for detecting electrically charged particles."

I'm was talking about the gradient in the electric field that changes the electrons path and kicks them out of the atom... and this not a interaction with another charged particle

The reason is that in your model or idea, light can't carry momentum. it is always a zero momentum phenomenon and that somehow, if light is detected in one spot, the whole spherical wave front dies instantly.

YES! and NO ! you misunderstood..

again..
a field is nothing that moves from one place to another, it's slope ( gradient ) changes over time. it does not carry any energy, it changes the path of charged particles, sure, but not like you were told it does...
the momentum change is not because some kind of a word "energy" is transferred, it changes because of the field's gradient ( slope ) change.
the charges carry on moving on they own, just change direction of motion because of the change in the EM

light is not a particle that travels from one point to another, light is the change in the gradient of the field
it's speed depends on the density of the field it is propagating in, so it is slower in glass for example... ( many many charged particles, high density of the field)

also... a wave of 299,792,458 meters has not less or more "energy" ( again, is just a word for something not physical ) than a wavelength less than 10 picometers ( gamma radiation )...
the only thing that matters is the "speed of change in the field gradient"... that's all... this is what you call energy !!
"slower change - no electrons kicked out, faster change - electrons kicked out"

but I have told it some dozen pages back here on this thread... again, nobody listen


BTW: just a small comment about your complains...
The Homestake experiment (sometimes referred to as the Davis experiment) was an experiment headed by astrophysicists Raymond Davis, Jr. and John N. Bahcall in the late 1960s. Its purpose was to collect and count neutrinos emitted by nuclear fusion taking place in the Sun. Bahcall did the theoretical calculations and Davis designed the experiment. After Bahcall calculated the rate at which the detector should capture neutrinos, Davis's experiment turned up only one third of this figure.

let me translate it for you...
- Its purpose was to collect and count neutrinos emitted by nuclear fusion taking place in the Sun
...so it was already based on a theory and not a discovery of any kind ( you see the implementation of terms ?? sun - nuclear fusion ?? , NO! )

- Bahcall did the theoretical calculations and Davis designed the experiment.
...so one made stuff up, the other made an detector to "see it"

- After Bahcall calculated the rate at which the detector should capture neutrinos, Davis's experiment turned up only one third of this figure.
...so, the detector was not quite how it should be, an then there was a problem...

- The experiment was the first to successfully detect and count solar neutrinos, and the discrepancy in results created the solar neutrino problem.
...so, translated, we on the right track, but we need more money, turned out it's more complicated..

sure the neutrino problem was "explained"... why not another fairy tell story... all working fine till now

yes... I'm trolling by using wiki... think !


one more thing.. the so called "wave collapse"... there is non !
electric field is the "messenger".. the coupler
magnetic field is the "executing", acting field

you can detect more than one "light" from the same source at the same time, it is not like if we see all the light from the star nobody else can see the star... ...or... if you make an electron emit a wave, you can detect it all around it ( if the detectors are in synchrony )

originally posted by: InTheLight
This thread trespasses into the philosophical here and there.

relating or devoted to the study of the fundamental nature of knowledge, reality, and existence.

is this not what is called the physics ?

..but this is some quite interesting statement...
are you distinguishing between physics and the reality ? ...sure for knowledge

a reply to: KrzYma

I read your post, you translated nothing, most of this information is discussed in my thesis... KrzYma... you telling is an interesting thing since you want to tell someone who can demonstrate a much better knowledge and who has real experience... and that person can easily show that your concepts skirt around reality. So, make another thread and stop hiding in this one... Trolling from wikipedia... its funny really since its clear you had no clue to any of that information or history until I pointed you at it.

There you where telling me how a neutrino detector is built... siting one method... and then saying neutrinos don't exist.

And now, suddenly after i gave you a bunch of information and wow, your an expert suddenly...

Make a new thread, stop hiding in this one... i put it to you that you won't, because you have nothing really to say, and you'd rather not the public argument that you are highly misguided... or trolling.

a reply to: ErosA433

it's good you calm down and try to talk... appreciate it !
you said I "translated nothing", to you ? but you not the only one reading person here, right ?

Make a new thread, stop hiding in this one...

NO, a new thread comes up first and all the trolls give they comments about God and whatever they think it is..spamming...
thanks! I stay here, kind of ... nobody cares it is old.. the thread here...

BTW. looks like you really comfortable in the position you think you are "someone who can demonstrate a much better knowledge and who has real experience... "

so tell me how gravity works?
tell me what is inertia ?
or contact me PM and i will share my knowledge for free...

its funny really since its clear you had no clue to any of that information or history until I pointed you at it.

...do I really need to compare "your knowledge" to mine ??
you do know that knowledge is just a word for experience and it is different for everyone ?

you really think I grow up on you ??
nice... everyone is judging by himself

NO! ... I use wiki in hope this is the right language to maybe at least understand me...

Okay I have deep question, I try best:

If a photon or wave is hitting my eye it makes me see the light from where it bounced off.
How many photons get back out from my eye where the sensor heads sit.

0? If all go out again.. I reword the question:

If they go out and only giving the sensors impulses or energy, how many energy is transfered in %.

I understand, photon or wave, it donot matter how we define it. Important to me is, the big question...

the information from it (wave, photon) if it leaves, has been changed. If a nother sensor can catch this photon or wave and analyze, can it calculate how many energy has been substracted from it? If they bounce out.

I think they donot bounce out. Because pupils show black, this means to me, nothing is reflected, all absorbed.

The reason why I ask, is if the photon or wave is spinning, it may give force into the sensor heads. Maybe we can build super telescope to see around planets and reconstruct a map of universe using the light bounce stations.

then we can map universe in 4D or not?

3D and time/position. Just a thought?

This means, I see black pupil not because of reflection from it but abscence off it? Like a black hole..

Like: there cannot be shadow without light.
Is there a name for this phenomen? I know, black holes...

I learned something and I maybe see connection to another thing. So I want to read up on.

Funny I read that black holes convert stuff into information.
Our eyes also do this, but in another way.

I think, maybe there is patterns in this and there is sweet spot or something for best information converting.

Like, peripheral vision?

originally posted by: Oleandra88I think they donot bounce out. Because pupils show black, this means to me, nothing is reflected, all absorbed.

No it just looks that way. They have a hard time to bounce out because it is a spherical shell with a small hole in it.

You can see inside if the light is intense enough. Doctors do it to check the retina. It can also be seen in photos as red-eyes. The reflectivity is strongest in the red wavelength (about 10%).

Many animals have an extra reflective layer behind their retina that gives them superior night vision and the typical eyeshine (glowing eyes at night).

originally posted by: Oleandra88
Okay I have deep question, I try best:

If a photon or wave is hitting my eye it makes me see the light from where it bounced off.

If photons bounce back then you you don't see those personally but as moebius says your eye doctor can see them bouncing back when he shines a light in your eye. You don't see the photons that bounce off, the photons that are absorbed by your photoreceptors are what end up sending signals to your brain.

then we can map universe in 4D or not?

I think in some sense we have mapped some of the universe in a type of 4D already. Parts of space which are relatively empty have relatively "flat" spacetime, with not much curvature of the space or effect on time, whereas parts of the universe with a lot of matter like galaxy clusters have a mapped matter density which does have an effect on time. Here's an example of a portion of such a map of warped space-time. The darker the color the more dark matter, the more warping of space-time, the more clocks will tend to run more slowly, and the more gravitational lensing will occur.

Unprecedentedly wide and sharp dark matter map

Figure 4: An example of 3D distribution of dark matter reconstructed via tomographic methods using the weak lensing technique combined with the redshift estimates of the background galaxies.

Hello Arbitrageur,

I read this and maybe I understand not half off what you write with the space time.

But you write, the photon is then the signal to the brain.

1 photon is then only 1 signal on a photoreceptors. How do we make map or picture from it?

and how do we know we see this picture before? it is different all time. Like I look at a auto and I know it is a auto or car.

and then I see a nother car and I know it is car. it has same shape but different.

is this huffmann entropy decoder? I ask, I see this and other things:



what is this??

a reply to: Arbitrageur

Parts of space which are relatively empty have relatively "flat" spacetime, with not much curvature of the space or effect on time, whereas parts of the universe with a lot of matter like galaxy clusters have a mapped matter density which does have an effect on time.

... ??? what exactly do you mean if you say "have an effect on time" ??
to my understanding, time is not a thing, it is a word that is used to describe "a change"...
if one planet is here, as I see it, and than.. after I went to sleep and woke up, the planet position changed, than I say,
the planet moved "such or such" distance over the time of my sleep period.

how can you see time changed ?? what does it mean to you, time changed ??
is time a constant that only changes if matte is present ??
how does matter density have an effect on time ? it is turning time blue if its denser and red if it not so dense ?

my next question is... and now I'm sure on topic with this thread... how exactly do you measure the "curvature of the space"
ha... what is the curvature of the space and how one can see ( detect ) ?? it would be the first question at all...
is apace bending the same as bending a stick ???

originally posted by: Oleandra88
Hello Arbitrageur,

I read this and maybe I understand not half off what you write with the space time.

A picture is worth a thousand words so just try looking at the curved arc in this picture and try to think about what would make it look like that, instead of like a normally shaped galaxy. Something is warping, or distorting the view, right?

Abell 370: Galaxy Cluster Gravitational Lens

But you write, the photon is then the signal to the brain.

That's not exactly what I wrote. The photon absorbed by the photoreceptor doesn't go directly to the brain, it initiates a process that ends up sending a signal to the brain.

1 photon is then only 1 signal on a photoreceptors. How do we make map or picture from it?

I'm not sure it's a physics question, it's more like neuroscience and I'm not an expert in that field but I think it's safe to say the answer is we don't really know exactly how that works but we have some clues and researchers are trying to figure it out.

One thing we know is our visual perceptions don't seem to be hard wired like say the imaging system for a digital camera or smart phone cam. I was fascinated by this experiment where people put on apparatus that made the world look upside-down, and the brain adapted so that 10 days later, the world started looking right-side up.



Actually the physics of optics says that without the inversion optics, our eyes see the world upside-down on the backs of our eyes normally, and the brain normally flips that so we see it "right side up". So when people wear the inversion glasses, that makes the image on the back of the eye right side up and since the brain is normally flipping that, you see things upside-down at first. But after enough time adjusting to this input the brain starts to change how it processes the image.

We don't have a good understanding of how this happens nor the other things you asked about though they are topics of ongoing research relevant to things like self-driving cars, being able to recognize objects. If you want to read about some of this ongoing research, here is an interesting article about it:

How the brain recognizes what the eye sees

originally posted by: KrzYma
sure the neutrino problem was "explained"... why not another fairy tell story... all working fine till now

yes... I'm trolling by using wiki... think !

You're definitely trolling, and I reported it to the moderators, because the wiki article you refer to on the solar neutrino problem does not say the explanation is a "fairy tell story[sic]". If you actually read the explanation you've shown zero comprehension of what it said and if your comprehension is that bad there's no point in trying to answer any of your questions, so I'm just going to ignore your posts from now on. I think you actually have the capacity to try to understand what the wikipedia article says about that topic but you show no interest in having an intelligent discussion about it.

Delbert Larson may not agree with mainstream views but at least he tries to understand them and engage in intelligent conversation about why he thinks his alternative ideas may have some merit.

If you ever do decide to try to engage in intelligent conversation, one thing you should learn is the language of physics. Different terms have different meanings and physicists work pretty hard to define terms, assign them units if appropriate, etc. When you want to talk about "is it a thing or isn't it?" this seems like childish semantic gibberish to me and probably to most physicists since the 1930s. I've never seen a physics definition of "thing" and the common definition is pretty ambiguous and not very constraining, so I suggest discussions about "is it a thing or isn't it?" should stay on the playground. People who want to understand physics can learn the terminology physicists use and become familiar with the experiments and what they tell us about the natural world.

The non-quantitative gibberish spewed by you and the electric universe folks (there is a lot of overlap even if you say you're not an EU supporter) is actually worse than being wrong, it's what can be referred to as "not even wrong", meaning it's just word salad that can't even be tested quantitatively, and without such it's not possible to do any real science. The "electric universe" idea is a very comfortable one for those who fear or lack understanding of math, because they never seem to use it, nor do you. Math may not be the answer to everything, but you can't do science without it so stop pretending otherwise. This is a good article about the child-like thinking of people who support the electric universe ideas (which you may try to deny but it sure sounds like you too):

The People Who Believe Electricity Rules the Universe

The electric universe concept does not meet the National Academy of Sciences' definition of a "theory," which is "a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence" and "can be used to make predictions about natural events or phenomena that have not yet been observed."

In physics, theories need math. That's how you predict, gather evidence, verify, disprove, and support. But EU theory isn't big on math. In fact, "Mathematics is not physics," Thornhill said. While that equation aversion makes the theory pretty much a nonstarter for "mainstream" astronomers, it is the exact thing that appeals to many adherents.

"They don't blind you with science," said Rasjid Smith, who learned EU theory from YouTube. "It is understandable to a capable schoolchild."

I think whether or not you admit you support EU ideas, your non-quantitative approach is exactly the same so I think this citation can serve as a suitable response to all the claims you try to make telling us how the universe is, without using any equations or math; that's scientifically a "non-starter" as the article says.

a reply to: Arbitrageur

sure you can ignore me.. but this thread is "ask any question about physics"... isn't it ??

what exactly do you mean if you say "have an effect on time" ??

what is the curvature of the space and how one can see ( detect ) ??

is apace bending the same as bending a stick ???

I think those are real physic's questions, or not ??

so... you reported me to the moderators.. OK
do you hope they ban me so you don't have to deal with my thinking anymore ??
you did it because the wiki article I refer to on the solar neutrino problem does not say the explanation is a "fairy tell story"... ????

OOOOKKEYY...

so.. your thinking is limited to what is written on wiki and elsewhere ? no self thinking ??

fairy tell story was my comment to this article..

OK
I do you a favor... I stop posting here... makes no sense anyway

but!

while I'm leaving... here


electric-currents-in-outer-space-run-the-show

still don't have the answer how you measure the curvature of the space !!!

repeat... you can only count or compare things, not more...

BTW: to be really honest... ? Oleandra88 is trolling... nobody is so dumb !! and anybody that is, would not post here...

Hi, longtime lurker here, been reading and enjoying this thread since the beginning, with the exception of a couple of people like Kr**** hopefully he really has gone as promised.

Could someone please point me in the correct direction regarding understanding dimensions please?
I mean I understand when they say (in the case of string theory) that there are maybe 10 dimensions but we do not see them because they are very small. Maybe true, maybe not, but fair enough as far as it goes.
But then when thinking on the large scale I read that the theoretical Branes (for example a gravity brane) are also considered to be "extra dimensions", so I'm struggling because (1) they are extremely large and (2) they appear to be physical spaces/objects.
I know it's all theory anyway, but I'd like to understand better, is there any consensus? Thanks

a reply to: Moley

The string crowd introduced additional spatial dimensions because they need them for their models. To hide them you can make them compact, essentially like a tiny closed loop. The other approach is to simply constrain (parts of) physics to certain dimensions, like having gravity act in more dimensions than the other fields.

Mathematically it is all just fine. Whether it makes physical sense is another question. I am not aware of any experiment showing any extra physical dimensions.

I was reading a thread over in Space Exploration and have some questions about the expansion of the universe.

The cosmological scale of the universe is described as being flat. If the speed of light can vary with time, why doesn't the cosmological “shape” of the universe change? The galaxy clusters must have differing densities – so as the universe expands, why wouldn't “bubbles” appear where density is greater? In other words, wouldn't the rate of expansion be different in various parts of the universe due to the density of matter i.e. galaxy clusters? Does gravitation of large masses change the rate of expansion in different areas of the universe?

It's confusing because special relativity describes our local time frame where c cannot increase, but then everything changes once we're looking at the universe way “out there” because of time (I think). If c can vary “out there” why would we expect Euclidean geometry or thermodynamics or anything else apply “out there”? If by some magical system we were able to go “out there”, near the horizon, which laws would apply? Would we experience local time frame rules or the “out there” rules?

It just seems to me that these local and “out there” rules should merge. Why should the speed of light be restricted locally and unrestricted "out there"?

a reply to: Moley
a reply to: moebius
Good question and good answer, thanks to both of you!

originally posted by: Phantom423
I was reading a thread over in Space Exploration and have some questions about the expansion of the universe.

The cosmological scale of the universe is described as being flat. If the speed of light can vary with time, why doesn't the cosmological “shape” of the universe change?

Yes the universe is described as having a "flat" cosmological geometry.

But, if you go to Florida or Kansas, and look in all directions it can look pretty flat too. The Earth is more or less spherical but you just can't see the curvature because it's relatively small from your point of view as an observer on the ground.

Like everything in science when you dig into details, you find that the best we can do is try to put limits on such observations, so we can't really say with certainty the geometry of the universe is flat, only that like trying to see the earth's curvature in Florida or Kansas, if it's curved, the curvature is so small we haven't been able to detect it. Another way to put it is if the universe is not flat and let's say it actually has a spherical geometry, the sphere must be very large to look as flat as it does to us.

Carrying that analogy a little further, we can see the earth is not a perfect sphere, it has mountain ranges, and valleys and canyons that deviate from the spherical shape (plus other non-spherical attributes due to rotation etc). So in that analogy I would look at the geometry of the universe similarly, in that if the geometry is spherical first it must be a huge sphere and second there can be local variations on the sphere analogous (not exactly) to mountain ranges on the sphere of earth.

Same thing if the universe geometry is perfectly flat, that doesn't mean it can't have variations in local regions, because as you suggest it certainly does, explained here:

Is space flat or curved?

According to Einstein’s theory of general relativity, massive objects warp the spacetime around them, and the effect a warp has on objects is what we call gravity. So, locally, spacetime is curved around every object with mass.

Mass also has an effect on the overall geometry of the universe. The density of matter and energy in the universe determines whether the universe is open, closed, or flat. If the density is equal to the critical density, then the universe has zero curvature; it is flat.

This graphic I posted earlier shows the how mass density varies and as we know mass can curve local spacetime:

Unprecedentedly wide and sharp dark matter map

So yes if the universe is really flat, those colored areas are deviations from the overall flatness, in those specific areas. So the question is, are those colored areas variations of an overall flat shape or variations of an overall spherical (or hyperbolic) shape? Those local variations don't determine the overall shape by themselves, but in aggregate I suppose they ultimately do which is part of the reason those analogies like mountains on a spherical earth are less than perfect.

It's confusing because special relativity describes our local time frame where c cannot increase, but then everything changes once we're looking at the universe way “out there” because of time (I think). If c can vary “out there” why would we expect Euclidean geometry or thermodynamics or anything else apply “out there”? If by some magical system we were able to go “out there”, near the horizon, which laws would apply? Would we experience local time frame rules or the “out there” rules?

It just seems to me that these local and “out there” rules should merge. Why should the speed of light be restricted locally and unrestricted "out there"?

These are good questions. Some people criticize physicists for assuming "constants" are "constant", but are they? You can actually find some research into investigating if this is the case or not. Here's an interesting article discussing that question and some of the research done.

Have physical constants changed with time?
I think you understand that in cosmology, time and distance are correlated so when he asks if constants change with time that's also related to distance, in cosmological terms.

Over the past few decades, there have been extensive searches for evidence of variation of fundamental "constants." Among the methods used have been astrophysical observations of the spectra of distant stars, searches for variations of planetary radii and moments of inertia, investigations of orbital evolution, searches for anomalous luminosities of faint stars, studies of abundance ratios of radioactive nuclides, and (for current variations) direct laboratory measurements.
...
So far, these investigations have found no evidence of variation of fundamental "constants." The current observational limits for most constants are on the order of one part in 10^10 to one part in 10^11 per year. So to the best of our current ability to observe, the fundamental constants really are constant.

Maybe as observations get better we might find some deviations in what we think are constant but so far, the constants really seem to be constant.

If I had to guess why you think they might be different further away, perhaps you read that nothing can travel faster than the speed of light locally, but the most distant galaxies in the observable universe are receding at three times the speed of light. So you might wonder why can things out there go faster than the speed of light, but they can't do that here? Am I close?

As I tried to explain in the other thread, they aren't traveling through space faster than light anywhere. The constants and the rules are the same (insofar as the investigations referenced above have shown), so nothing can travel through space faster than light out there, just like right here. The space between us and the most distant galaxies is increasing so that's how they can appear to recede at three times the speed of light, but they do not move through space that fast, they don't move any faster than light *though* space, just like in our corner of the universe.

In the raisin bread analogy, the raisins are said to be like galaxies and the expanding bread (which can be thought of like expanding space) increases the space between the raisins. So any raisin can only travel through the bread at a certain speed limit. However the bread expanding is something else, and the raisins on opposite ends of the loaf can be separated more from each other due to the expanding dough in between, without traveling through the local bread at all. So the speed limit saying how fast the raisins can move through the bread doesn't apply to how fast the entire loaf of bread can expand, in that analogy.

Dimensions are often used to expand upon concepts. Such as for example the Pauli exclusion principle in which no two fermions can occupy the same quantum space with the same quantum state.

So this works fine with our regular matter, Electrons we say are either spin up or down so we can get two in a single space. Now we can expand on this and this is what is done for treatment of fermi-gases in extreme circumstances such as degenerate material in compact stellar objects such as white dwarfs and neutron stars.

Here we give a dimensional treatment to momentum. So we get 'space' x, y, z. and so called k-space, Kx, Ky, Kz and so a quantum state is a defined space and vector momentum.

Sounds a bit odd but it is one such example.

a reply to: Arbitrageur

Thank you for the detailed reply. All good points and descriptions. Putting all this together, I found a diagram which shows the expansion of the universe. I labeled the diagram with red arrows and my own comments. Below the diagram is a more detailed explanation of what I'm thinking:



The Popcorn Theory

Bowl of popcorn = original dense inertial point or mass
Big bang = provides energy to launch the popcorrn into the air

After launch, popcorn is distributed randomly, with each kernel having a different mass (disregard gravity for a moment)
The act of launching popcorn from bowl provides energy of momentum (assume popcorn in bowl is a dense inertial mass ).

For each kernel:
If mass x velocity > gravitational force, kernel continues motion – space expands between kernels.
If gravitational force > mass x velocity, kernels condense – fall back into a dense mass – contraction

Assuming the expansion scenario, each kernel would have a specific energy which is the mass x c squared . If momentum is added to the system via the little big bang at 7.5 B years ago, the new momentum would be the original momentum from the big bang plus the momentum derived from the little big bang.

Since any mass creates a space/time curvature around it, the outward movement of the kernels is curved.

If gravity reaches zero, the total kernel structure would break up at some point.
If gravity is asymptotic, the gravitational force, however small, holds all the kernels in some total shape or form forever.

So why do we need dark energy? All the energy to produce the scenario described above was contained in the original dense point or mass. If dark energy existed, it would have had to be in that original dense point. The way I'm reading it, dark energy just appeared out of nowhere at some point and became the driving force for expansion.

I don't know if gravity can ever be zero or if it's asymptotic. I never read about a zero gravity place in the universe. It seems like zero gravity couldn't exist and that there's some gravitational force between all matter in the universe, however small.

Regarding constants, the article you posted said:

So far, these investigations have found no evidence of variation of fundamental "constants." The current observational limits for most constants are on the order of one part in 10^10 to one part in 10^11 per year. So to the best of our current ability to observe, the fundamental constants really are constant.

Does the universe recognize our constants? If it did, wouldn't that prove symmetry? I don't think anyone has proven symmetry. The LHC proved the Higgs. But it didn't discover any other new particles which I think were supposed to be related to symmetry. Not sure about any of this – just my impression from reading articles.

Thanks again for answering questions, especially with reference material.

originally posted by: Phantom423
If momentum is added to the system via the little big bang at 7.5 B years ago, the new momentum would be the original momentum from the big bang plus the momentum derived from the little big bang.

I never heard it called "little big bang" and I don't like that term, but there is a point about half the present age of the universe according to George Smoot where the effect of dark energy started to become significant. It's not like it suddenly appeared, but if our guess is right that it is the vacuum energy property of space, if there's not much space between things in the first half of the age of the universe, then dark matter doesn't have as much effect. As the space between things continues to increase, then with more space the effects of dark energy become more significant, which makes sense to me.

The design of the universe | George Smoot

So why do we need dark energy? All the energy to produce the scenario described above was contained in the original dense point or mass. If dark energy existed, it would have had to be in that original dense point. The way I'm reading it, dark energy just appeared out of nowhere at some point and became the driving force for expansion.

You could misinterpret what George Smoot says that way when he says expansion started to accelerate when the universe what half it's present size after 16 minutes in the video. Maybe it sounds like a binary switch was turned on at that point but he's oversimplifying that and a lot of other things to address a non-technical audience. The increasing effect of dark energy is gradual, not something that suddenly appeared (it would be related to the cosmological constant Lambda in the math at the link below for the Lambda-CDM_model if you want to review the math).

Dark energy was nearly non-existent in that original dense region since it's probably a property of space and with so little space in such a small volume the amount of dark energy would be insignificant. Of course we aren't positive that dark energy is a property of space but that's our current best guess. Anyway this plot shows accelerating expansion did not kick in suddenly at any specific point, but as George Smoot says the expansion rate is accelerating far more in more recent times.

Lambda-CDM model


Why do we say there's dark energy? Because without it the expansion of the universe would not accelerate which observations show it's doing.

Does the universe recognize our constants?

I'm not sure what you mean but the universe doesn't care what we think or what models we make, it does what it does and we are pretty sure all our models are wrong in the sense that they are only approximations of what nature does, generally within a limited range of conditions. We are fairly certain that in the hottest densest part of the big bang conditions were beyond our current theories, so we don't understand what nature really did at first.

If it did, wouldn't that prove symmetry? I don't think anyone has proven symmetry.

Symmetry is somewhat of a broad term but one example of symmetry is that the speed of light is considered to be constant in all reference frames. As for proof, we can never "prove" anything is true, we can only say a theory is consistent with observations until it's not, and then it might be proven wrong if observations disagree with theory. But so far the idea that the speed of light is constant seems to hold up in our tests, along with other predictions of relativity.

The LHC proved the Higgs. But it didn't discover any other new particles which I think were supposed to be related to symmetry. Not sure about any of this – just my impression from reading articles.

As I said symmetry is a broad term and the speed of light being constant in all reference frames is one example. There are other types of symmetries like C-symmetry or charge symmetry which deals with charges of particles and anti particles, like the electron and positron are similar except have opposite charges, so they have a type of symmetry.

Another type of symmetry you allude to is supersymmetry, which posits that there are much heavier supersymmetric particles, some of which probably should have been found by the LHC but as you suggest were not found so I can't say for sure that supersymmetry is dead, but I've read articles saying maybe it should be by now. In any case the LHC and any subsequent accelerators will probably continue the search for unknown particles including any possible supersymmetric particles.