“The slow philosophy is not about doing everything in tortoise mode. It’s less about the speed and more about investing the right amount of time and attention in the problem so you solve it.” -Carl Honore
Einstein's theories of special and general relativity tell us that there's no Universal, preferred frame of reference. But that doesn't necessarily mean that our physical Universe doesn't have an average frame of reference, one which minimizes the relative speeds of all the galaxies to one another.
While the Earth rotates, orbits the Sun, which revolves in our galaxy, which moves in the local groups, which in turn is gravitationally attracted to all the galaxies, groups and clusters in the Universe, the leftover glow from the Big Bang allows us to reconstruct exactly how fast we move relative to that. And it turns out that there is a particular frame of reference that's better than all the others, and we're not at rest.
Go get the full story of how fast Earth moves through the Universe -- and some real science -- on this non-foolish 1st of April.
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“How fast does Earth move through the Universe?”
I guess the answer is: many different speeds.
The earth’s speed
-orbiting the sun,
-revolving in our galaxy,
-moving in the local groups,
-and inflating into a bigger universe.
What is our speed for the last?
You got us. The answer is "we don't know, therefore Jesus." Checkmate, science!
@See Noknowledge #1: If you have to "guess the answer", you can't read very well, eh?
1) Paragraph 2: 30 km/s
2) Paragraph 4: 200-220 km/s
3) Paragraph 17: 627 km/s
4) Zero. The metric is locally at rest everywhere during cosmological expansion.
Thanks eric. You just made me spit coffee on my keyboard.
To know-it-all Michael Kelsey #3:
So, you’re saying the earth’s speed in cosmological inflation (i.e. “cosmological expansion”) is zero?
If all things in the cosmos are expanding at zero speed, how can there be expansion?
Why do you choose to bring religion into this?
Why can't you just stick with the science?
@ SN #6
Because they can't help themselves. It's a self importance thingy..
Because I know you, SN, and you will almost certainly use your questions as a jumping off point to imply there's something wrong or problematic with current science. But okay, maybe I jumped the gun. Prove me wrong. Don't do that on this thread, and I promise I won't jump the gun in a similar way on future threads.
To eric #8:
Now, can you answer my question to Michael?
I mean the Michael of the SLAC National Accelerator Laboratory?
@ See Noevo
With regards to your question #4 I ask Is the Universe actually expanding or rather gaining mass?
"To know-it-all Michael Kelsey #3"
To a mental midget, someone knowing something you don't is both an annoyance to you and some sort of indicator of error in your "mind". Why is that?
Is your god, who if it existed rather than a figment of your imagination, also a scorn-worthy know-it-all?
Though oddly enough, the only thing Mike demonstrated was his ability to read your native language. A task you failed at.
"Now, can you answer my question to Michael?"
What relevance does it have? All you claimed was you don't know what acceleration means or what expansion means, despite making assertions based on your lack of knowledge.
Acceleration isn't the expansion of space. It's expansion of space.
@ SN #5
"If all things in the cosmos are expanding at zero speed, how can there be expansion?"
Because not all things are expanding, only spacetime. And it's expanding everywhere at same rate. Thus everyone localy is at rest in their own reference frame, the distance to "next" reference frame is what has increased.
Zero is the Earth's speed*.
* with respect to me!
@See Noknolwedge: The dynamics of cosmological expansion have been "explained" to you multiple times, both in the posts from Ethan which you obviously don't or can't read, and in many, many comments which you also don't or can't read.
Here is the technical description. If you have any ability to think on your own, you can use each of the individual keywords to learn much, much more about the topic until you gain understanding. I'll mark each keyword with asterisks to make it even easier for you.
The changing *scale factor* in the *FLRW metric* leads to a separation of *comoving* objects in the universe over *cosmological time*. It does not induce any motion in those objects, which will remain locally at rest (*local rest frame*) unless acted on by local forces such as gravity. In the latter case, those objects will have a *peculiar motion* which is entirely unrelated to the cosmological expansion.
To Michael the SLACer #15:
“The changing *scale factor* in the *FLRW metric* leads to a separation of *comoving* objects in the universe over *cosmological time*. It does not induce any motion in those objects, which will remain locally at rest (*local rest frame*) unless acted on by local forces such as gravity. In the latter case, those objects will have a *peculiar motion* which is entirely unrelated to the cosmological expansion.”
Everybody else got that?
Question: I understand that the *FLRW metric* assumes the universe is *isotropic.* If that's so, it doesn’t make sense to me, because, obviously, the universe *does* look *different depending on where you are in the universe*.
Another question: In the billionth of a second after the Big Bang started, how expansive was the universe then compared to now?
I could be wrong but I thought the latter was vastly bigger than the former. And to go from little to big requires expansion, and expansion requires speed.
But you won’t tell us what that speed is.
Oh, well. Time for some pizza.
@See Noknowledge #16: I'm not here to spoonfeed you, in a futile attempt to answer your willfully ignorant "questions."
I gave you the detailed, technical explanation on purpose, and even highlighted the specific terms you should research on your own, so that you could dig as deeply as necessary for you to get satisfactory answers.
You're clearly unwilling to do that. You have proved, repeatedly and on many different fora, that you are entirely unable to entertain any information which doesn't fit your narrow and unrealistic worldview.
The speed of expansion is, at present, about 70 km/s per megaparsec. That is the normalized time derivative of the scale factor (1/a da/dt). If you don't know what that means, look it up.
"Everybody else got that?"
Yes, as a matter of fact we did. But it took weeks if not months of study.
The grapes are sour.. go cry more.
Congratulations, you have not only demonstrated that you don't understand isotropy, but also embedded the embarrassing display in a sentence that bizarrely suggests you've been visiting different parts of the universe.
To Michael the SLACer #17:
Thanks for the 70 km/s per megaparsec.
But I understand that’s just an average, or at least, just for galaxies relatively close to us.
I understand that galaxies *farther* from us are moving *faster*!
I thought the standard cosmological model relied on (arguably invalid) assumptions of consistency (e.g. homogeneity, isotropy).
This would be another case of the universe behaving differently depending where you are in it.
This is just painfully clueless.
Do you "think" that the Hubble constant varies by location?
I really can't do better than what Michael and Sinisia have already said re: the expansion. But a couple of responses to your later questions:
Re: isotropy vs. anisotropy. You seem to make a big deal about what you perceive to be anisotropies where phyiscs expects isotropy. Nothing could be further from the truth. Inflation predicted both large-scale homogeneities and very small scale anisotropies. Lo and behold, when were able to actually look at the CMB in detail, we found it to be anisotropic at exactly the scale we expected it to be to match an inflationary model. IOW, it's data matched our predictions. You could've easily looked this up yourself by googling "CMB anisotropy."
Re: expansion not being consistent. It is consistent, but there are local motions on top of it. At the risk of you abusing my analogy, this works similarly (but not exactly like) two passengers on a moving train having different speeds relative to a train-watching bystander because one of those passengers is walking toward the front of the train and one is walking toward the back. You're claiming that because they have different velocities relative to the observer, the train must be moving at inconsistent speeds.
To eric #22:
So, the use of the standard cosmological model necessitates the universe’s homogeneity and isotropy,
except when it doesn’t.
And yes, analogies can be a bit*h.
But at what speed is the train, I mean, the universal inflation, travelling at?
Within our plane of reference in the metabolic cycle the earth as a part of the finite volume of mass that is our energetic whole moves relative to the energetic whole. The energetic whole is a finite volume of mass the same as a quantum of infinite pure energy. Infinite pure energy fills space as a dimensionless, omnipresent medium as a potential force without motion. Relative to any moment the entire metabolic cycle fills the here and now of its energetic whole with the same volume of mass as its quantum of infinite pure energy.
Relative to motion of any event Within the evolution of its metabolic cycle all events are at variable rates relative to an immobile energetic whole. An energetic whole is a finite volume of mass the same as its quantum of infinite pure energy.
@See Noknowledge #23: Asked and answered, you ignoramus.
SN @23: as Michael said, you've been told the answer to the question. In post 3. In post 13. And in post 15. Did you just not understand the answer, or do you understand the answer and choose to repeat the question anyway?
That's right, it predicts homogeneity at some scales and not at others. And those predictions were then borne out by measurement. I get that you're trying to use sarcasm and over-simplification to make it sound like postdiction instead. By all means continue. I can't think of a better advertisement against your beliefs than to watch you pretend not to get Michael's explanation (just as one example), or try and twist it to say something it obviously didn't say. The beauty of the internet is lurkers can see Michael's post. And yours. And judge each for themselves.
From the folks at Cornell (with my EMPHASES):
“…the universe's expansion is determined by something called the Hubble constant, which is approximately equal to 71, measured in the technically useful but conceptually confusing units of "kilometers per second per megaparsec." In more sensible units, the Hubble constant is approximately equal to 0.007% per million years -- what it means is that every million years, all the distances in the universe stretch by 0.007%. (This interpretation ASSUMES that the Hubble "constant" actually stays CONSTANT over those million years, WHICH IT DOESN’T, but given that a million years is extremely short on cosmic timescales, this is a pretty good APPROXIMATION. It also assumes that when we talk about the "distance" between two galaxies, we are referring to the distance between them right now -- that is, the distance we would measure if we somehow "pressed the freeze-frame button" on the universe, thereby stopping the expansion, and then extended a really long tape measure between the two galaxies and read off the distance. There are many other distances that can be defined in cosmology, but this is the most useful one for the current question.)
IF we use the definition of distance given above (AND ONLY IF we use this definition and no other), then the Hubble constant tells us that for every megaparsec of distance between two galaxies, the APPARENT speed at which the galaxies move apart from each other is greater by 71 kilometers per second.”
and you posted that explanation from Cornell why? You maybe think it says something different that what has been written before? It doesn't. Says the exactly same thing Michael has written just using different phrasing. Hint.. APPARENT speed is not INTRINSIC velocity... and so on.
Problem is you don't understand it one way or the other. Which is sort of tragic, since you've been trolling here for a year or so. That you didn't learn anything in the time spent is..well just sad.
It turns out that Sidney van den Bergh has posted an arXiv note on the omission of Abbé* Lemaître's introduction of cosmic expansion in the MNRAS version of the original paper.
* Noted for S.N.'s "benefit," although I suspect it's run back to Breitbump or someplace similarly comfortable after the full-caps tantrum.