101–110 of 295 posts
I guess people are going to act like I'm a lunatic, but of course it's wrong. Dark Energy violates basic conservation of energy, and the evidence for it has never been strong or convincing. Lots of us have been saying this since forever.
Earlier quoted context omitted.
Speaking from the pov as a former astrophysicist, that definition of redshift is not quite accurate. While we have observed the universe expanding since Edwin Hubble published his findings 90 years ago, it was in fact the Friedmann equations produced 10 years earlier that established how it would work within the context of general relativity. The Universe is expanding at every known point at the same time at the same…
> However, if you were to change our relativistic reference frame to match a distance galaxy's As a causal science enthusiast I am lost, how does one change our relativistic reference frame?
Or is it really? What if it's staying perfectly still, and YOU'RE the one moving?
... How could you even tell?
The principle of Relativity is that you cannot tell any difference, for the laws of physics are the same whether you are moving or the galaxy is moving. The theory of Special Relativity describes which mathematical transformations you need to go from one description to the other (in the absence of gravity, which is a General Relativity concern). Philosophically, the way of unifying these involves mixing up Space and Time, in which various observers cannot agree on a single version of things like speeds and time and energy levels, into a unified Spacetime, which they all can agree on.
"Changing your reference frame" simply means picking something different that you consider to be at rest.
Earlier quoted context omitted.
Speaking from the pov as a former astrophysicist, that definition of redshift is not quite accurate. While we have observed the universe expanding since Edwin Hubble published his findings 90 years ago, it was in fact the Friedmann equations produced 10 years earlier that established how it would work within the context of general relativity. The Universe is expanding at every known point at the same time at the same…
> The Universe is expanding at > every known point at the same > time at the same rate This part I don't get (I am in no way versed in astrophysics). If I am in a box, and that the box grows 10%, but that at the same time I grow 10%, what has changed? I mean, if every point in the universe expands at the same rate at the same time, what does it change? Relatively speaking, everything is the same size before and after…
This scales up to forces in between atoms, molecules, and bits of matter. It's only at the very large scales (larger than galaxies) that all the forces that are holding the stuff together starts getting overwhelmed by the expansion of space and it starts to pull things apart. The expansion is so gentle that even relatively weak gravity can hold galaxy clusters together even as space grows.
In other words: space gets bigger, but matter doesn't. It more or less stays the same size.
Earlier quoted context omitted.
> The Universe is expanding at > every known point at the same > time at the same rate This part I don't get (I am in no way versed in astrophysics). If I am in a box, and that the box grows 10%, but that at the same time I grow 10%, what has changed? I mean, if every point in the universe expands at the same rate at the same time, what does it change? Relatively speaking, everything is the same size before and after…
Your interpretation of the expansion is incorrect. Basically, it looks like all points are moving away from each other over large distances. It is easier to understand in 2D: Imagine a deflated balloon with two dots drawn on it. When you inflate the balloon, its 2D surface increases, which results in the two points "moving away" from each other, without either of them actually moving. It‘s just that the surface on wh…
That is to say, what is my ruler that is untethered to the surface of the balloon?
Earlier quoted context omitted.
Speaking from the pov as a former astrophysicist, that definition of redshift is not quite accurate. While we have observed the universe expanding since Edwin Hubble published his findings 90 years ago, it was in fact the Friedmann equations produced 10 years earlier that established how it would work within the context of general relativity. The Universe is expanding at every known point at the same time at the same…
One thing I've never understood is this. How do we tell the difference between the expansion of space and the dilation of time? Given that space and time are crudely specking intertwined (spacetime) how do we know that the effect we see -- redshifting -- is due to the spatial expansion at every known "point" and not the temporal expansion (contraction?) at every known moment? Could not the spatial size of the univers…
(If it doesn't fit, then it's just wrong.)
Earlier quoted context omitted.
Speaking from the pov as a former astrophysicist, that definition of redshift is not quite accurate. While we have observed the universe expanding since Edwin Hubble published his findings 90 years ago, it was in fact the Friedmann equations produced 10 years earlier that established how it would work within the context of general relativity. The Universe is expanding at every known point at the same time at the same…
> However, if you were to change our relativistic reference frame to match a distance galaxy's As a causal science enthusiast I am lost, how does one change our relativistic reference frame?
Earlier quoted context omitted.
Your interpretation of the expansion is incorrect. Basically, it looks like all points are moving away from each other over large distances. It is easier to understand in 2D: Imagine a deflated balloon with two dots drawn on it. When you inflate the balloon, its 2D surface increases, which results in the two points "moving away" from each other, without either of them actually moving. It‘s just that the surface on wh…
What's still not clear is how I know the other point on the surface of the ballon is moving away from me? I measure it as 9 tick marks away. After inflation it's still nine tick marks. That is to say, what is my ruler that is untethered to the surface of the balloon?
Earlier quoted context omitted.
>> Is he implying that other cosmologists have proceeded as if dark energy is well evidenced? As a non-cosmologist just reading HN I would say yes. Not quite as extensively as Dark matter though. I personally think that's a mistake too based on my limited research on the topic. If these are both overturned it will be a huge blow to "scientists" credibility in the eyes of the public. That's how invested they are.
Scientist have no idea what dark matter or dark energy is so it’s not like our world would be overturned. If it turns out to be wrong assumptions, that’s fine. Although it would be embarrassing.
Sabine Hossenfelder comments on this paper: Dark Energy might not exist after all https://youtu.be/oqgKXQM8FpU
Amusingly, this video is about entirely different work that also calls into question the basis for claims about dark energy. Nobody seems to be saying how the two results interact. Taking away dark energy twice could give us negative dark energy, which would be fun. I don't know whether unexpected negative dark energy would be more embarrassing than unexpected zero dark energy.