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IAI_Admin OP t1_jc6itm9 wrote

Abstract: The evidence is that dark energy is responsible for the rate of the universe’s expansion. While the name makes it sound like a spooky force, it’s the cosmological constant Einstein added to his theory of gravity in 1917. There is a backing of sorts from quantum theory, which predicts a cosmological constant but of a substantially different value. Unifying the value predicted by quantum theory with the value observed from the expanding universe would be a great discovery, but even the most sophisticated theory is constrained by observational evidence which will always be imperfect and incomplete. Theories will always be an approximation, and never an account of ultimate reality, argues James Peebles.


kris_lace t1_jc73em9 wrote

The cosmological constant is one of the more mind blowing values in science.

If we took a ruler the length of the observable universe and mapped some of the main constants along it; gravity, speed of light, weak nuclear force etc. We could move the value of those constants along the ruler by millions of miles to a new value - and the forces still more or less act the same way and nothing is changed in reality.

But if we moved the cosmological constants pointer even one inch along that ruler to a new value; the universe as we know it would cease to exist. It has 120 zeros after the decimal point, and then a two.


Ape_Togetha_Strong t1_jc7etnq wrote

It's honestly amazing how often dark energy is brought up without mentioning that:

  1. non-zero vacuum energy is a prediction of QFT

  2. non-zero vacuum energy would contribute to the cosmological constant

Instead people just use the same line over and over about how it's completely mysterious and we have no idea what it is.

It's nice to see an article written by an actual astrophysicist for a popsci audience that mentions these things and actually clarifies some of the things that popsci "journalists" like to make sound as sensationalized as possible.


danielravennest t1_jc84ysh wrote

> popsci "journalists" like to make sound as sensationalized as possible.

Of course they do. We live in a clickbaity world, because they need to attract eyeballs to earn ad revenue. That's why you see headlines about asteroids all the time. But when you read the article, you find they will miss Earth by millions of miles (usually) and are not a danger. But you already clicked the story, and ad counter went up.


YawnTractor_1756 t1_jc7hqqh wrote

I find articles talking about dark matter/energy to be manipulative, here is why.

If you read the article itself you'll find that those names were invented as merely labels for the inconsistencies in how Universe behaved. So yes dark energy "exists" because inconsistency exists, and dark energy is merely a label name for that inconsistency, but nothing more. It's not given nor claimed by scientists that it is proven to actually exist as energy.

The manipulative part is that the words used in those labels bear their own meaning. "Matter" means something objectively detectable made of physical particles which you're able to interact with. But we don't actually know if that's the case.

What is more concerning is statements like this:

>Perhaps dark matter will never be detected, apart from its gravitational effects. Even so, that would not be an argument against its existence

Saying that if we cannot detect something does not mean that something does not exist its basically Russell's teapot claim. It is very concerning to see that in an article that claims to be scientific.


Ape_Togetha_Strong t1_jc7n4yd wrote

That's not manipulative. It's reality.

>Matter" means something objectively detectable made of physical particles which you're able to interact with.

No it doesn't. And you don't get to decide that it does. But it does tell you something about the way "dark matter" is expected to behave based on observation. So does the "energy" in dark energy. These words are meaningful within the context, although like with all things in physics, words will always fail to convey a concept based on math, because they're meant as labels for things you are already informed about, not as a way to convey understanding.


YawnTractor_1756 t1_jc8iqji wrote

Of course it is manipulative. Just like Tesla's "Full Self Driving" which is not fully self driving is manipulative. Words have meanings and contexts of their own, which was defined way before me, or the guy who coined Dark Matter, which is neither dark nor matter. Inventing context where black means white and claiming it's not confusing (and ultimately manipulative) is ridiculous.


Ape_Togetha_Strong t1_jc8l2fm wrote

Yeah, sorry, that's just not how it works. It's not misleading to call something that doesn't interact with electromagnetism, and thus light, "dark", and it's not misleading to call something that is acting like matter "matter". Whatever hangups you have about these words are really on you. It's not even close to misleading, and even when the short terms given to complex ideas are "misleading", it still doesn't make them manipulative. Things catch on, and once that happens, it isn't getting undone. That's not a conspiracy to manipulate you.


lilrabbitfoofoo t1_jc7ismq wrote

Agreed 100%.

>It is very concerning to see that in an article that claims to be scientific.

Anything with Dark Matter or Dark Energy is going to be clickbait. And so we see these piles of drivel almost daily here. :(


dern_the_hermit t1_jc8f9ce wrote

> If you read the article itself you'll find that those names were invented as merely labels for the inconsistencies in how Universe behaved.

That's just dismissively reductive. Those "mere" inconsistencies were like half a dozen separate observations that differed from expected values by a pretty exact amount, noted by many people, across many decades. This wasn't some flippant, casual invention but the product of rigorous observation and calculation, challenged at every step by multiple other parties with alternate theories that, themselves, do not explain all of the aforementioned observations.

By your complaints, I offer you just don't understand the data.


YawnTractor_1756 t1_jc8j6oh wrote

I don't know why you put so much stress on it, I was not in any way arguing or diminishing inconsistencies, I realize how they are very important.

I was arguing dark matter and dark energy are confusing and ultimately manipulative terms. Claiming inconsistency exists is one thing, claiming dark matter* exists is another. It would be like naming it "dark overlords" and claiming dark overlords now exist, without repeating all the time that there are no actual overlords, it's just a label.


dern_the_hermit t1_jc8m2py wrote

> I don't know why you put so much stress on it,

You wrote a big ol' screed baselessly attacking the article and the subject matter. Maybe don't do that?


Cthu-Luke t1_jc9rpy5 wrote

Yes but everyone knows it's just a label, if they're too ignorant to realise then that's their bad, and tbh, it has literally zero bearing on everyone's day to day existence....for now anyway.


the_JerrBear t1_jc7n19a wrote

yes, the bit where he says that no evidence doesn't mean it doesn't exist is frankly embarrassing


dern_the_hermit t1_jc8fda9 wrote

"apart from its gravitational effects" is a pretty huge thing to just ignore like that, bud.


the_JerrBear t1_jc8h0zt wrote

sir bud dude, dark matter is a numerical correction to GR to match observed gravitation in galaxies, so he says "apart from" because it would be absurd to suggest that gravitational observations are direct evidence of dark matter


sight19 t1_jc9u6zv wrote

And BAO. And CMB anisotropy. And the Bullet Cluster. And DM free galaxies. And early -universe structure formation. DM works on a huge range of scenarios. Even MOND requires DM to function properly...


dern_the_hermit t1_jc8ho05 wrote

Literally all scientific models are made up to match observations. That's how the scientific method works.


the_JerrBear t1_jc8jd8d wrote

yes, and so far no explanatory models for dark matter have been successful. Including dark matter as a parameter to match observed data is not the same thing.


dern_the_hermit t1_jc8lsj0 wrote

We don't have a model for dark matter. It is called "dark" because it is unknown. We are currently in the early stages of creating a model to explain observations, one good enough to make predictions. Several models, actually, of which dark matter - that is, "matter that only interacts gravitationally" - is the only candidate that can explain the widest range of observations.


the_JerrBear t1_jc8wdpc wrote

it's called dark matter because it only interacts gravitationally, not because we can't explain why it should be there. dark matter is not a bad model, it does explain observations well. we are not exactly in the early stages as far as that is concerned. nor are we in the early stages of attempting to explain what exactly that matter is, a lot of things have been ruled out that seemed promising at first. i would agree that the dark matter hypothesis is the most attractive solution available to us now, but the continuous failure of dark matter particle experiments, along with no unified theory to work from, makes it difficult to say that it is probably the right one. General relativity does not predict dark matter - we infer it from our observations. No experiment has been able to confirm hypotheses about the origins of dark matter, and there have been quite a few of them so far. It's good that we've come up with lots of ideas, and it can't hurt to keep trying, but we also know that general relativity and the standard model are not complete theories, so it seems unreasonable to me to argue that, because general relativity is nearly perfect, we shouldn't doubt dark matter.


dern_the_hermit t1_jc8xhkb wrote

> it's called dark matter because it only interacts gravitationally, not because we can't explain why it should be there.

No, the notion that it only interacts gravitationally came much later. Previously it was assumed that it might simply be... dark matter, regular old gas, dust, rocks, stellar remnants, black holes, etc. that were not luminous. Take a look at MACHOs and WIMPs for theories about "dark matter" being regular standard model stuff that simply wasn't glowing.

It wasn't until decades later that "it only interacts gravitationally" became the dominating notion, entirely based on the preponderance of observations indicating something like that.


the_JerrBear t1_jc8ysof wrote

Okay, I concede you that. It started out as "matter we can't see," and today a popular interpretation of that is that it doesn't interact with light at all. My mistake.

But, that also wasn't really my point.


dern_the_hermit t1_jc8zs1t wrote

Your point was some crude dismissal of dark matter based on what seems to be a gross misunderstanding you have. Sorry for correcting your misunderstanding. It must hurt your feelings, being corrected.


the_JerrBear t1_jc90lsw wrote

at no point have i dismissed dark matter, i have only presented arguments against the evangelization of dark matter, which this article supports. you argued beside the point, and have now volunteered yourself to exit the conversation.

rest easy, your words are as sharp as you are


dern_the_hermit t1_jc91i3y wrote

"the bit where he says that no evidence doesn't mean it doesn't exist is frankly embarrassing" was pretty damn dismissive dude, GTFO with that dishonest-ass nonsense lol :D


the_JerrBear t1_jcfency wrote

if you interpreted that as an outright dismissal that dark matter is correct, then again, you have entirely missed the point... Saying that "not having evidence doesn't mean it doesn't exist" is not a strong argument for dark matter, or a strong argument against alternatives. It's pleading, and doesn't really imply anything meaningful. I hear it when people ask for proof that god exists.

I don't understand why you insist that I have claimed dark matter is incorrect, maybe I am failing to communicate my point properly, but that definitely is not it at all. I would appreciate it if you took some of your valuable time to respond to literally anything else that I have actually said, thanks


YawnTractor_1756 t1_jc8jx9e wrote

That doesn't mean any scientific model is correct. I can make a model with gravitons to explain gravity, it doesn't mean they exist. Same with dark matter.


dern_the_hermit t1_jc8l4mp wrote

All models are only as good as their ability to explain observations and make predictions.


YawnTractor_1756 t1_jc8lcof wrote

That's false. I can imagine that electrons are little conscious demons with mass of electron and charge of electron. It will explain things right, but it will contain unnecessary and unproven assumptions.


s1ngular1ty2 t1_jcm8i6e wrote

The names were invented for REAL observations. They observed things happening that could not be explained without extra mass or energy. The names are made up but the phenomena is real.

All names are made up by the way.


YawnTractor_1756 t1_jcmg2tq wrote

>things happening that could not be explained without extra mass or energy

Of course there are ways to explain observations without extra exotic mass or energy, there are several of them including as simple ones as "we've just miscalculated the actual mass of the gas in the universe" to differences in constants through time and/or space. Possibility of different explanations is the whole point of this thread.

Sure, extra mass from exotic particles was the easiest knee-jerk explanation to additional gravitational pull, but it does not make it the right explanation, and decades later we still have no idea if that exotic matter/energy is even there, yet the name continues to confusingly assume it is, and articles that say "dark matter is real" are inherently confusing because they can mean "exotic unknown matter is real" or "observations discrepancies we labeled 'dark matter' are real". And authors know it but still do it for clicks.


InformalPermit9638 t1_jc9874x wrote

Cool article. Personally, I'm still in camp MOND.


s1ngular1ty2 t1_jcm8b5q wrote

How though when it doesn't explain all observations? Most scientists don't believe MOND is the answer because of this.


InformalPermit9638 t1_jcm9nlw wrote

Care to convince me? My mind is open to facts. Everything I've watched and read so far make me favor MOND over the currently favored cosmology.


s1ngular1ty2 t1_jcmbxtf wrote

Gravitational lensing, CMB analysis, the bullet cluster, etc all prove dark matter exists and MOND doesn't prove how any of these work.

So it's pretty clear MOND is not the answer.


InformalPermit9638 t1_jcmcf5d wrote

I'm watching now, this article is the genesis of my own belief:

Edit: that's a really basic video, I was hoping for something a little more direct lol


the_JerrBear t1_jc7ls2o wrote

these are some frustratingly weak arguments from a nobel laureate. I wonder if that comes with the "Albert Einstein Professor Emeritus" title


NotAHamsterAtAll t1_jc8802a wrote

Dark Energy = Epicycle invented to explain the hypothesis of an expanding universe.