Ask any question you want about Physics

a reply to: Arbitrageur

Neat, thanks. Hadn't seen that one before.

a reply to: Arbitrageur

Dark energy is only part of the puzzle because before 1998 we already thought new space was being created as the universe expanded, even without dark energy. The idea then was the expansion was something left over from the big bang. Then in 1998 when new data showed the expansion was accelerating, dark energy was proposed to explain the acceleration, which may just be vacuum energy, which is not well understood.

I do understand to my limited extend the evolution of expansion theory.
But for how long do I have to wait for the answer?)))))LOL Not in my lifetime, I guess))

Instead, I am here on ATS, best place in the universe, to speculate for entertainment mostly.

Here is what science has as of right now...Universe is expanding at ever increased rate. Period.
There are other issues that more or less related to that fact. Age of the universe calculated according to Standard Model does not match observations (celestial objects appear further than calculated age of the universe from the moment of Big Bang.

Second -- where is all that energy that drives expansion is coming from in ever increased quantities?
Wait a second, I just wanted to know if anyone has explored the possibilities I was talking about above, that's all.

Universe is expanding at ever increased rate...fine. Without going into too much of a detail, what logical solution anyone could come up with for an answer?

I have three options.

First is a white hole. It has given birth to our universe from the black hole from the 'other' universe that has reached critical mass and exploded, sort of. And why not? Say, our universe via black holes merger, after accumulating 'under it's belly' all the matter, releases it into new set of dimensions. Same 3D set but some different phase. Don't ask me what that means...hahaha...the phase shift would be a condition overlaying same as our 3D cosmos but somehow preventing overlap allowing further new expansion. In this scenario 'where energy driving expansion comes from' could be solved as said white hole right now did not reach its peak siphoning elementary matter from the old one into another. That's why it is still accelerating.
I am not talking about 'faster than light' thing because we have already discussed it somewhere earlier in this thread.
Although, this scenario does not explain discrepancy between observed 'age' of cosmos and calculated. 'Observed' suggests events have begun way before current model gives us.

Second option, is universe is a wave function. I mean, it is a wave. Literally, 3D wave. It is of the shape of the donut expanding outwards. As it travels, new space is created in front and destroyed behind it.
This scenario, in my view, solves three problems. Energy is conserved within the wave as it is 'rolling' ahead making new space in front and ceasing it's presence behind while 'rolling'. No need for extra input, it is the same energetic 'packet' in vector motion.
It solves age of universe discrepancy between 'observed' and 'theoretical'. That's because if two objects lay along circumferences of the ripple, as ripple grows (expands) naturally these two objects would get further apart. In this case 'new space' would be due to the wave itself getting larger in circumference. (hope my English is not mixing up words). This way it is becomes clear why calculations from the moment of Big Bang do not meet actual observations. Calculations in this case are right because the light caught on the detector had to go extra path following shape of donut instead of straight path (opposite to direct distance between say some quasar and us) and can be disregarded.

Yes, you will ask me 'how come space is growing in all directions no matter where we look,coz 3D donut clearly has boundaries and space should grow only to the 'left' and to the 'right' from us compare to the 'ball' shape where it also has 'depth'. Fine. But if we assume space-time is the surface of events with no depth then at some point we with our detector should make a complete round around of the donut slice and see ourselves as past event in theory. That has been discussed on Phys dot org at some point. Question is how it is possible to identify reflection of solar system? Not possible. The only way to know for sure is in a few billion years to catch our first radio transmission, but that's too long to wait.)))LOOLL Ok, that was all about the age thing.

Third option would be (least probable) is that there is no expansion at all. It is just massive celestial chunks moving between observed light source and detector as we conduct our measurements. This would make light red shift giving an impression of expansion.


uffff...))) cheers all)

originally posted by: greenreflections
Instead, I am here on ATS, best place in the universe, to speculate for entertainment mostly.

Did you read the quote from Nima Arkani-Hamed about how difficult it is for him as a theoretical physicist to come up with new ideas that aren't obviously wrong? The converse of that is of course that for non-theoretical physicists, coming up with ideas about theoretical physics that are wrong is quite easy...and common.

Here is what science has as of right now...Universe is expanding at ever increased rate. Period.
There are other issues that more or less related to that fact. Age of the universe calculated according to Standard Model does not match observations (celestial objects appear further than calculated age of the universe from the moment of Big Bang.

That's like saying my daughter's age of 3 years old is more than 3 centimeters. Does that even make sense? No. You're comparing a time to a distance and they have different units, so it's somewhat of a nonsensical statement. Since the universe is expanding, the most distant objects now are more than 14 billion light years away even though the universe is thought to be less than 14 billion years old, but that's how our model of the expanding universe works. The speed of light is not a constraint when applied to the expansion of the universe, in fact the expansion is faster than the speed of light beyond a certain distance. Observations match our model. Saying somehow that observations comparing a time to a distance don't match is just an incoherent misunderstanding on your part though if you have a source talking about what you're trying to say, feel free to cite it, but I promise you don't understand it and/ or you're confused about what it says.

Second -- where is all that energy that drives expansion is coming from in ever increased quantities?
Wait a second, I just wanted to know if anyone has explored the possibilities I was talking about above, that's all.

Universe is expanding at ever increased rate...fine. Without going into too much of a detail, what logical solution anyone could come up with for an answer?

Your three options make little sense to me, and I think you're probably over-complicating things. It may be just as simple as "dark energy aka vacuum energy is a property of space, aka the vacuum". That's what many experts seem to think. The reason I said vacuum energy is not well-understood is that we don't have a model to predict or calculate why the vacuum energy should be the observed value, but we have lots of problems with our models like those, where we plug in observed values because our models don't allow us to calculate everything yet.

Anyway your third option "there is no expansion at all" seems to contradict your own statement that "Universe is expanding at ever increased rate. Period." What happened to your "period"? That's more like a "but, maybe it's not" instead of "period". LOL. Actually we should get more accurate data about expansion rates over the next decade, so we'll see where the data takes us but it will still show expansion, maybe not the same amount that was calculated in 1998 when the first papers on this came out.

a reply to: Arbitrageur

Your three options make little sense to me, and I think you're probably over-complicating things. It may be just as simple as "dark energy aka vacuum energy is a property of space, aka the vacuum". That's what many experts seem to think. The reason I said vacuum energy is not well-understood is that we don't have a model to predict or calculate why the vacuum energy should be the observed value, but we have lots of problems with our models like those, where we plug in observed values because our models don't allow us to calculate everything yet.

Thanks.

Food for thoughts for me.

Yes, property of space. Sooner or later that property has to be addressed, no? And with this space-time vacuum energy, how might it explain Big Bang? That vacuum energy had to undergo some non trivial event..what was the trigger for the property of space-time to start expansion?
Was there a beginning if property of space-time is to ever expand at accelerating rate as observed?


cheers)

a reply to: Arbitrageur

What if dark energy is actually a former of gravity that acts solely on spacetime itself? It wouldn't interact with any matter, only the vacuum energy in any given region. The vacuum energy could be seen as exerting a sort of outward pressure in every direction in the actual fabric of spacetime, and is countered by a field that has a fixed quantity of energy or potential. The remnant expansion from the big bang could have pushed spacetime past a tipping point where this field had density enough to counter the force of the vacuum energy. As spacetime expands, the field gets weaker per given volume of spacetime, and it becomes a runaway effect? Just spitballing here, but I figure if I don't pop up with some laughable theory every now and then, I'll lose my street cred in this conversation.

originally posted by: greenreflections
Yes, property of space. Sooner or later that property has to be addressed, no?

People are trying to figure it out but so far nobody has, that I know of. One prediction for the expected amount of vacuum energy has been called the worst theoretical prediction in all of physics because observation mismatches the prediction by such a wide margin, so there's plenty of room for progress with that as your starting point.

And with this space-time vacuum energy, how might it explain Big Bang? That vacuum energy had to undergo some non trivial event..what was the trigger for the property of space-time to start expansion?

We think there was more than one phase of expansion so it's not as simple as a "trigger". prior to the expansion we observe today, inflation has been proposed in the early universe to help explain the homogeneity of the cosmic microwave background.

Was there a beginning if property of space-time is to ever expand at accelerating rate as observed?

Was there a big bang? We think so. Was there such a thing as "space-time" before the big bang? Nobody knows what existed before the big bang. There is an excellent documentary interviewing some leading theoretical physicists exploring these questions, and I posted a link to it earlier in the thread but if you didn't watch it then, the link no longer works as the video has been removed from youtube. I found it pretty interesting, and there are lots of ideas on the table, including re-considering whether the big bang actually happened. At least one of the physicists interviewed seems to think it didn't, at least not in the way our commonly used models describe it.

The ideas about the earliest parts of the big bang tend to be speculative.

originally posted by: pfishy
a reply to: Arbitrageur

What if dark energy is actually a former of gravity that acts solely on spacetime itself? It wouldn't interact with any matter, only the vacuum energy in any given region.

I have no idea what that means, former of gravity? I haven't seen any indication that dark energy has anything to do with gravity.

I've seen some people try to say it's sort of like "anti-gravity" since it pushes apart instead of pulling together like gravity does, but even that is extremely inaccurate and misleading because it doesn't seem to behave like "anti-gravity" as anti-gravity would push matter apart, and dark energy doesn't seem to be related to matter like gravity is, so anti-gravity would have significantly different behavior than dark energy.

a reply to: Arbitrageur

Oh, come on now. Don't nitpick because my phone has an ambitious autocorrect.
It was having trouble trying to frame the idea in that reply. Maybe this will be more comprehensible.
What is there is a gravity-like field that interacts directly with spacetime itself, and only spacetime. This field has an absolute, fixed potential or energy, whichever works better. This field acts to hold spacetime together in a fairly static volume. The big bang released vastly more energy than this field could equalize against, hence inflation. And the leftover expansion energy from the big bang inexorably stretched spacetime out, slower and slower, but constantly, until this energy, combined with the vacuum energy of spacetime reached a tipping point for the field. If the expansion from the big bang had been weaker, or had the vacuum energy value been lower, the field would have eventually reached equilibrium and the predominant force would become gravity moving forward to a big crunch model.

is the moon in the sky at night all the time for every country, except for the new moon phase, of course.

a reply to: Davg80

It isn't always up for just the right hours. There are plenty of times it can be seen during the day. As the moon orbits Earth, itis visible for a different period of time each day. Only on a full moon will moonrise almost immediately follow sunset, and vice versa. Also, depending on the phase of the moon (very slim waxing or waning crescent) city light pollution could make it difficult to see, I guess.
Yes, though, the moon is visible from every country on earth, just not necessarily limited to night time.

a reply to: pfishy

i live in the UK and i see it during the day sometimes and always see it at night... every night. so i figured if i can see it during the day there must be countries that cant see it at night. but here in the UK its always there, i think last night was a new moon and i just noticed how clear the stars were when its a new moon.

a reply to: Davg80

The countries opposite the UK on earth will still see the moon for a period of time around night. Except during the New Moon, I suppose, when it mainly tracks the Sun across the sky. Like when we get a solar eclipse. It is exactly positioned between the daytime hemisphere and the sun. So the night side of the planet won't see it at all that night.

a reply to: Arbitrageur

Hello, Arbitrageur. On "asking any question about physics" - have you had the time to look at my thread on a New Relativistic Quantum Mechanics? Do you have any thoughts?

Also, a reply to: mbkennel

I have responded to your post on my thread. Please let me know if you have any further comments.

---

I have added at the bottom of my thread the experience I have had with Physical Review Letters on this matter. I am now attempting to wrap up the comment period and plan to soon prepare a paper for Physics Essays. Prior to doing that I would appreciate any comments either of you may have. I welcome comments from others as well, and don't mean this to be exclusionary. However I am asking you two specifically, since I believe you each may be knowledgeable on the subject matter.

Thanks.

Sorry for the off-topic post, but I just wanted to say that I started a thread in the Video Games forum that I think a few of you wonderful folks might be interested in. And it actually is (sorta kinda) physics related.

a reply to: Davg80

Due to the earths tilt there are times of the year where it can be seen during the day too.

Physicists hate this question but I'll ask anyway because it intrigues me.

Tesla proposed that a medium, or an ether, exists by which all matter travels. I think of it as a parallel dimension with a spectrum which humans can not see or feel. Einstein himself considered the idea of a luminiferous aether. He actually stated that if proved, his very own special relativity theory would become null and void.

With dark energy and dark matter, string theory and QM, are we any closer to proving that an actual ether does in fact exist?

I believe until it is proven, faster than light space travel (warp drive), anti-gravity and other incredible physical achievements will never be possible.

Scientific theories are are just that; theories which are never hard fact. Theories which are proven fact at the time get thrown out for newer, updated theories throughout history all the time.

Having a conspiracy orientated mind tells me that even with massive operations such as LIGO and LHC, discovering supporting data of anything having do with an ether will unfortunately never be made public. At least not in any of our lifetimes.

a reply to: Arbitrageur

Have wondered for decades . . .

take atomic particles . . . protons, electrons, neutrons . . . and, I suppose the particles more basic than those.

IS THERE ENOUGH variability in their . . . how to put it . . . operations, functioning . . . that they could uhhhh . . .

transmit . . . basic 'words' . . . meaning . . . about their states, context . . . some such?

I've been skeptical that there's that much variability to them. But I'm an ignorant layman so I don't know.

= = =

And a related question . . . let's say there is sufficient variability for some level of communicative capacity . . .

as preposterous as it might be or seem . . .

is it conceivable that a collection of atomic particles . . . in an object or organism . . . could somehow comprise a more complex communicative capacity hooked together somehow?

= = =

And, could this communicative capacity use one or more of the dimensions beyond 3D, 4D for such communicating?

originally posted by: kushness
Physicists hate this question but I'll ask anyway because it intrigues me.

Tesla proposed that a medium, or an ether, exists by which all matter travels. I think of it as a parallel dimension with a spectrum which humans can not see or feel. Einstein himself considered the idea of a luminiferous aether. He actually stated that if proved, his very own special relativity theory would become null and void.



I believe until it is proven, faster than light space travel (warp drive), anti-gravity and other incredible physical achievements will never be possible.

the luminiferous aether is the time domain which consists of dark matter coupled to time.
A body at rest does not FEEL its mass until it moves and it feels its mass because it compresses time and dark matter in the direction it moves, giving rise to inertia.

Anti Gravity and ftl is possible now. Read the thread in my signature

Cheers

originally posted by: pfishy
Oh, come on now. Don't nitpick because my phone has an ambitious autocorrect.
It was having trouble trying to frame the idea in that reply. Maybe this will be more comprehensible.
What is there is a gravity-like field that interacts directly with spacetime itself, and only spacetime. This field has an absolute, fixed potential or energy, whichever works better. This field acts to hold spacetime together in a fairly static volume.

As I mentioned earlier, I've been listening to lectures by theoretical physicist Nima Arkani-Hamed lately, and much of the stuff he discusses is far too technical to go into here, but one of the simpler observations he's made is that he thinks "space-time" is doomed, and he says so do a number of his colleagues in theoretical physics but he doesn't name any other names. One example he gives for why he thinks so is that even if we had more advanced technology we still wouldn't be able to observe anything on a planck scale because attempting to do so would create a black hole. Therefore, he asserts, since Planck-scales can't be observed that probably means space-time doesn't exist at Planck scales. I can't say he's wrong but I'm not completely sold on that argument either, however I do think he's probably right about space-time being doomed in some sense, and since that's a pillar of general relativity it means GR is doomed, probably in the same way that Newtonian mechanics was doomed, meaning they will both be shown to match observation under certain ranges of conditions, but not all conditions. Most notably, GR yields an "unknown" result in its black hole "divide by zero" calculation, which I think is a better reason for it being "doomed" as universal model than the reason Hamad provided.

So if space-time is doomed, what's going to replace it? A quantum theory of gravity? Perhaps, we don't really know at this point. Anyway I thought you might find it interesting these leading theoretical physicists who work where Einstein used to work are saying space-time is doomed if you're trying to build a model around space-time.

a reply to: delbertlarson
I made a comment in your thread but unfortunately I wasn't of much help. However I'll repeat what I said earlier here that it appears to me that George Box was right in his roughly restated assertion that "All models are wrong, some are useful". If Box is right, and I have every reason to believe he is based on everything I've seen, then your model like every other model we've ever made is wrong in some way. So the important question which remains is whether the model is useful. Such utility is not yet apparent because further calculations are needed, but I see a mathematician gave you a tip on how you might proceed with those calculations. Good luck with those.

originally posted by: kushness
Tesla proposed that a medium, or an ether, exists by which all matter travels.

Tesla was born in 1856 so he wasn't even alive in 1818 when luminiferous aether was proposed by Fresnel

Timeline of luminiferous aether

1818 – Augustin Fresnel introduces the wave theory of light, which proposes light is a transverse wave travelling in an aether

As for the "by which all matter travels", have you got a citation for that? Exactly when and where did Tesla propose that? Luminiferous aether isn't proposed for matter to travel though, it's proposed as a propagation medium for light (which is not considered matter), somewhat like water is a propagation medium for water waves or like air is for sound waves.

I believe until it is proven, faster than light space travel (warp drive), anti-gravity and other incredible physical achievements will never be possible.

I don't follow your logic there. Air as a medium for sound to travel through is an impediment to fast travel, as spacecraft can travel much faster outside the atmosphere than in it. What makes you think warp speed is more possible with aether than without it? Anyway Einstein called "space-time" the "new aether" though his terminology didn't stick, we just call it s"space-time" and nobody calls it "new aether".

1920 – Einstein says that special relativity does not require rejecting the aether, and that the gravitational field of general relativity may be called aether, to which no state of motion can be attributed.

Having a conspiracy orientated mind tells me that even with massive operations such as LIGO and LHC, discovering supporting data of anything having do with an ether will unfortunately never be made public. At least not in any of our lifetimes.

If you said a drug company had a cure for cancer but wouldn't release it because they make more money selling drugs for treating it, at least that conspiracy theory sounds plausible because of the profit motive coupled with corporate greed. However I don't see any such profit motive or any other motive for not announcing the aether if it was discovered so I don't follow your logic at all. Nothing at LIGO or the LHC would fall apart if aether existed, and as Einstein said special relativity doesn't preclude the existence of aether.

If you want to say that aether exists, you must then define precisely what you mean by aether, what properties it would have, and what if any of those properties would be detectable in experiments. As the citation above shows Einstein says GR's space-time is the new aether. If that's what you mean by aether, it's already accepted. If you mean the old luminiferous aether exists then there are two possibilities that I see:

1. You think the Michelson-Morley and subsequent experiments were performed or analyzed incorrectly to give a null result when they shouldn't have. In this case you would need to describe what all the experimenters did wrong, but there were lots of experiments so I doubt this would be fruitful.
2. You think that the Michelson-Moreley null result was obtained correctly, but they were testing for the wrong properties of aether. This is conceivable, and in this case you would need to define the new experiment that would demonstrate the type of aether that you think exists.

a reply to: BO XIAN
This gets into the semantics of exactly what you mean by "communicate". We see chemical and electrochemical forms of communication between cells in living organisms to coordinate the efforts of the cells to keep the organism alive.

If you mean outside living organisms, like two individual hydrogen atoms, I would explain the process by which they form an H2 molecule as an "interaction". However if I was explaining this process to my young nephew I might inaccurately describe their interaction as a form of communication to simplify it for him, fully realizing that it's not really what I would normally consider "communication". So I guess it depends on what you mean by "communicate". We say particles interact, but when physicists say two like charges repel and unlike charges attract, the vocabulary is more one of interaction and not so much "communication" though if you define "communication" broadly enough I suppose it could overlap with interaction somehow.

If the "Big Rip" theory is correct, would the gravitational force of a singularity be able to overcome it?

originally posted by: pfishy
If the "Big Rip" theory is correct, would the gravitational force of a singularity be able to overcome it?

The "Big Rip" model is not correct, but even in the less aggressive accelerating expansion model where the cosmological constant is constant, the black holes at the center of each galaxy will probably dominate for a long time until the temperature of the cosmic microwave background becomes so low that they too will "evaporate" after maybe a googol years. Black holes with a mass larger than that of the moon won't evaporate under current conditions, and the CMB is cooling more and more slowly so that's why it will take maybe a googol years for the larger mass black holes to "evaporate".

Our "Heat Death" model may not be right either, but it's certainly got a better chance of being right or closer to the truth than the "Big Rip" model. Here's why I say the "big Rip" model is wrong:

No “Big Rip” in our Future: Chandra Provides Insights Into Dark Energy

the Chandra study strengthens the evidence that dark energy is the cosmological constant, and is not growing in strength with time, which would cause the Universe to eventually rip itself apart.

I'm just adding this part because I know it will make ImaFungi's head explode, and he would say if "nothing" weighs something then it's not really nothing, to which I would tend to agree, which is why we should call it "the vacuum" instead of nothing ("The vacuum" is not nothing). But that leads us to "Empty space is not really empty" which sounds like an obviously false tautology which appears to be true, so I can see why it might make some people's brain explode, not that mainstream scientists claim to have a firm grasp either, they can only report what the data show in research like this Chandra study, so far, and try to model it, but we still have no model to predict the observed amount of vacuum energy.

“Putting all of this data together gives us the strongest evidence yet that dark energy is the cosmological constant, or in other words, that ‘nothing weighs something’,” said Vikhlinin.