Airbrush

"Daylight saving time was first introduced in the United States in 1918 under the Standard Time Act as a measure to save on fuel costs during the First World War by adding an extra hour of sunlight to the day....

"In 2005, Congress amended the Uniform Time Act to expand daylight saving time to the period in effect today: Starting on the second Sunday of March and ending on the first Sunday of November, according to the Congressional Research Service. This move was again for energy saving purposes.

"A Department of Energy study following the amendment’s implementation found the extra four weeks of daylight saving time saved around 0.5% in total electricity daily in the U.S., equaling energy savings of 1.3 billion kilowatt-hours annually."

Who invented daylight saving time? Time change purpose and origins (usatoday.com)

I don't care which one, standard or DST, just stay with one. Anyone in favor of continuing to change the time twice every year?

8 minutes ago, swansont said:

As with all science, what we know is based on data and theory. The data are what we observe in nature and as the result of experiment, and the theory is the models we have that’s based on the data and has allowed us to make predictions. It’s privisional, since new data could require a modification of theory. But that’s what it means to know things in science.

We know the big bang was not an explosion in space because the evidence does not support that hypothesis.

 

Large numbers are beyond the average person, but not to scientists who deal with them in the course of their work 

What is the evidence that the big bang was not an explosion?

What is the likelihood that the expansion we are able to see continues to infinity (assuming a flat universe)?  I propose that even scientists are not comfortable with very large numbers.  The number of Planck volumes in our observable universe is less than 10 to the power of 200.

On 11/24/2023 at 7:54 PM, Bufofrog said:

As been stated several times the big bang was not an explosion, and it most certainly wasn't an explosion in a vacuum.

You sound so confident.  I don't think anyone knows if the big bang was an "explosion" or not, and we don't know anything about a pre-big bang vacuum.  With eternal inflation those don't work.  With a multiverse of universes what do you find between universes or big bangs?  They call it the "bulk."  Is that a vacuum?  What we call THE universe may be only ONE region of expansion and we like to project that to infinity because very large numbers are beyond us.  What does our big bang look like Graham's Number of light years away?  We don't have a clue.

On 11/11/2023 at 7:04 PM, Chris Sawatsky said:

I recently started a topic called "The Speed of Light" and one of the responces said "You're going to have to unlearn this common misconception if you want to actually understand cosmology. The big bang happened literally everywhere and was never a 'point', and there is no rushing of material from a point into 'empty space' so to speak." So Imust be reading the following wrong...

The  Big Bang  was the moment 13.8 billion years ago when the universe began as a tiny, dense, fireball that exploded. Most astronomers use the Big Bang theory to explain how the universe began. But what caused this explosion in the first place is still a mystery. 

A sphere exploded but did not expand in every possible direction simultaneously? Is Light not the fastest thing in the Universe? Are you trying to say that Lightspeed is not the fastest speed that anything can travel? Everything I read suggests that the Universe is expanding outward in every possible direction at the same time and began to do this approximately 13.4 Billion years ago

We don't know if the "big bang" happened LITERALLY everywhere.  We think the OBSERVABLE universe (big bang) began as a tiny dense region. 

Light has a fixed speed THROUGH space, but we don't know how fast light moves far beyond our observable horizon.  Cosmic inflation is much faster than light speed.  Everything you are talking about refers to our observable region of our big bang.  There certainly MAY be a central region of our observable portion of our big bang.

Here are a few of mine:

1.  "SAGITTARIUS A STAR" This title bothered me for many years until I figured it out.  Why do they call a supermassive black hole a "STAR"?  Black holes are NOT stars!  Then I finally realized it means "Sagittarius A ASTERISK."  That is dumb.  Call it "Sagittarius A Hole".

2.  Why not call:  Dark Matter = Unknown Gravity?  Why not call:  Dark Energy = Space Energy?  Because no can do, we must stay with the original racist terms.

3.  Why RPMs?  That means either "revolutions per minute" or "rounds per minute."  Call it something people, such as I, can relate to.  Say "RPS" or "revolutions per second" and "rounds per second" to save your reader from the doing math, dividing by 60, to figure out how fast that is.  A second is very easy to understand.  A minute is way beyond comprehension, unless you are a science expert.  Don't get me started with "megaparsecs" or "astronomical units" when you could easily use "light years" or "light days" or "light minutes" which are FAR EASIER for most people to visualize.

4.  Pedestrians who leisurely cross the street paying no attention to cars waiting for them.

Any others?

On 1/12/2024 at 6:15 AM, Phi for All said:

Seriously?! Not a single comment did that. Every single reply has told you exactly what the problem is with your argument. Now you're either engaging in bad faith, or you just can't grasp the concept that when the entire universe expands, it's NOT expanding INTO anything. It can't, because there is NOTHING else except the universe. If you can focus on this and stop ignoring it, you may begin to see and break this 20 year cycle of ignorance. We all wish you the best!

In a multiverse model there may be multiple, or an infinite number of, big bangs.  In that case each "universe" is finite in size, has a center, and edges expanding outward. The outer edge may have ANY shape and be moving at ANY speed since the edge is not constrained by space as it expands into the "bulk."

"In the bulk model, at least some of the extra dimensions are extensive... and other branes may be moving through this bulk."

Brane cosmology - Wikipedia

On 8/28/2023 at 10:02 AM, Genady said:

Globally, regionally, locally ... Mentally, culturally, behaviorally ...

Thank you for playing. As I don't intend to discuss this topic any deeper, I rather excuse myself.

Conditions on Earth are changing faster than people's minds change.  It takes generations for significant human changes.  We don't have time for that.  We need to adapt quickly or self-destruct.

16 hours ago, swansont said:

Where did you find it? Is it a credible source?

Most of this is beyond my understanding.

"Time and energy are Fourier conjugates (or more generally, spacetime and energy-momentum) and cannot exist in the physical reality without each other. In other words, GR states that spacetime is the field produced by matter just like the electromagnetic field is produced by charges. Vacuum solutions are unphysical, they don’t exist in reality. Their flaw is that the equations are solved without realistic physical initial conditions. This approach and resulting solutions are physically meaningless."

But then there is also this from the same source:

"No, general relativity doesn't make any claim as to whether matter must exist or not. In fact, the simplest of the solutions to the Einstein equations are vacuum solutions. For example, the Kerr-Newman blackholes and their special cases such as the Schwarzschild blackholes and Kerr blackholes. The dimensionality of spacetime is still 4D in these solutions with one dimension being time-like." 

general relativity - Does Time Require Matter to Exist? - Physics Stack Exchange

On 1/4/2024 at 5:15 PM, geordief said:

Is this a space with no time component?

A space that is ready to be populated with objects?

I think I am more familiar with a space that is created by objects reconfiguring themselves(in an overall expansionist way as per observations)

I think that is the orthodox view even if I am not up to speed with it.

 

It still seems difficult for me to imagine  the 3d universe existing on the 2d surface of the sphere

There doesn't seem to be room for the 3 dimensions.

Is it just an analogy?

And the universe is not hollowed out ,is it?)unless the "hollow" is somehow the past history-surely not that)

 

I was wondering if time can exist without matter?  This is what I found:

"GR states that spacetime is the field produced by matter just like the electromagnetic field is produced by charges. Vacuum solutions are unphysical, they don’t exist in reality."

Does that mean that if the big bang has a finite size, the outer 3d limits of the expansion could be expanding at ANY speed (assuming there is no infinite speed), and beyond that limit could be a region of no matter and therefore no spacetime, just "space" if you will?  No more spacetime, just space, until you encounter another big bang coming from another direction?

I thought one way to explain an accelerating expansion of the universe is our observable universe is located inside a great void, like a bubble surrounded by unimaginably great masses pulling our region of spacetime apart from all directions.

11 hours ago, Markus Hanke said:

Newtonian gravity has nothing to say about massless particles, so strictly speaking it makes no prediction here. However, if one assumes that photons have a very small but finite mass, then one can use Newtonian gravity to work out how they are deflected around massive bodies. Turns out that deflection angle doesn’t depend on the exact mass of the photon, so long as it is much smaller than that of the central body.

The result you get is off by a factor of 2 compared to actual observations - to get the correct angle, one must use GR.

How can one assume that photons have any mass at all?  I thought photons were energy and that is why they travel the speed of light.  How could any mass travel light speed?

21 hours ago, TheVat said:

These seem to be the Right's favorite conceptually empty attack phrases.  I have no idea what they really mean, nor do most people who use them.   It's impressive that politicians can get a quarter of the GOP to rank fighting these chimeras at the top of their concerns.

I'll bet if you actually defined the real meanings of woke and liberalism and presented them (minus those hot button words, or following them with "agenda") to your polled sample, you would get a much smaller group that wanted to "fight" them.  

For example, here is the actual definition of woke from Merriam Webster:

"aware of and actively attentive to important facts and issues (especially issues of racial and social justice)"

Yeah, my God, let's fight this looming threat of people attentive to important facts and issues, especially where racial bias in concerned!  This could destroy the basic fabric of American life and drain our precious bodily fluids!

Yes, "woke" as opposed to unconscious.  Dictators thrive on unconsciousness.  The level of mind-control is astounding.  Time to vilify education and awareness.  

18 hours ago, swansont said:

I asked “Are there any polls saying that this is a big issue with voters not already going to vote for TFG?”

So items of interest to GOP voters doesn’t answer this question. Most/all of them are voting for TFG. They are not the ones who will be convinced by facts, anyway. They’re too far into the cult to be deprogrammed.

So GOP voters will CLAIM items of interest because they can't state the truth, that they are simply enthralled by an entertaining celebrity, who struts around like a pro wrestler, and cracks wise about the evil other party.  If TFG were to state "inflation is not an issue, and the thousands at the border is nothing, and wokeness is no big deal" his cult of personality will turn on a dime to not care about those things either.  They can't be deprogrammed because their source of news is narrow, by choice.

22 hours ago, swansont said:

Are there any polls saying that this is a big issue with voters not already going to vote for TFG?

“68% of Americans say immigration is good for the country today”

27% say it’s bad, but if they are already in TFG’s camp, it’s not going to sway the election.

https://news.gallup.com/poll/508520/americans-value-immigration-concerns.aspx

And, as Phi has suggested, the do-nothing GOP can be blamed for not passing legislation; the president can’t pass laws by himself.

It might also be pointed out that this is a manufactured concern (surprise!) seeing as the number of immigrants in 2021 was about 1.5 million, lower than any pre-pandemic year this century. It was ~2.5 million a year under TFG, pre-pandemic

https://usafacts.org/state-of-the-union/immigration/

Topics of most interest to GOP voters:

1  Controlling Inflation - 53%  US inflation has been trending downward and GOP need to be made aware of this.  Unusually high worldwide inflation followed the Covid pandemic broken supply chains.  Worldwide inflation averaged over 8% for the year 2022 (US averaged only 6.5%.  US averaged 3.9% for 2023 so far, and down to an average of 3.3% over the past 6 months.)

Inflation Rate - By Country (tradingeconomics.com)

Historical Inflation Rates: 1914-2023 (usinflationcalculator.com)

2  Controlling Immigration - 36%

3  Fighting Liberalism & Woke Agenda - 25%

4  Able to Beat Biden - 25%

"Of the topics that we asked about, [GOP] voters were most concerned about “getting inflation or increasing costs under control” (53 percent of respondents selected this issue),...Other issues that were top of mind for voters were “controlling immigration” (36 percent), “someone fighting against liberalism and the woke agenda” (25 percent) and “ability to beat Joe Biden” (25 percent)."

Republican debate highlights and analysis: Fiery faceoff on Trump, Ukraine and more - ABC News (go.com)

15 hours ago, MigL said:

IOW, Seth, the axis, or principal dimensions, do not change in any way,; the 'projection' of the interval onto the axis, or principal dimensions, is what changes.

Singularities and infinities are essentially the same; a singularity is a point where an infinity arises.

No one needs to consider  the 'fade to gray', or any other kind of 'boundary' to the universe; a finite universe simply 'closes in' on itself, such that, if you 'looked' far enough away, you would 'see' the back of your head.

"If you 'looked' far enough away, you would 'see' the back of your head."

But would you see your back only if you looked in ONE direction, or every direction?  Would all straight lines of sight circle around to you from every direction?

Trump will win in 2024 IF Biden does not deal significantly with the border issue.  If Biden would deal with the border, that will neutralize the GOP's biggest weapon against him.  Or they will call him "Open Borders Biden."

On 12/27/2023 at 1:40 PM, Genady said:

The reply was:

It does not actually answer the question, "how fast". To answer this question, one needs to take the derivative, (11−t)′=t(1−t)2 .

This grows infinitely when t→1 .

Thus, the answer to the question "how fast is 'fast enough'?" is, "infinitely fast".

There are many functions that head for infinity as a numerator approaches zero.  Try to apply that math to the actual big bang.  Look at the biggest picture possible, the observable universe.  It resembles a homogenious sponge-like structure of galaxy clusters.  If you had to bet on only one or the other, what would you bet on? 

1 That homogenious, isotropic structure extends like that all the way to infinity? 

Or 2 That structure changes over distance, becoming scarcer or denser?

10 hours ago, Markus Hanke said:

No. What it means is that the answer to the question of “how much mass/energy is in a region of spacetime” depends on what kind of geometry that region has. Depending on considerations such as symmetries (Killing fields), asymptotic flatness etc a certain definition may apply, while other definitions may not work. So one has to be very careful which one is to be used.

Note also that being in relative motion wrt to a gravitational source does not change the geometry of spacetime, it only changes the coordinate description of it.

This is an interesting explanation.  Thank you.  Can anyone state this in terms more understandable to non-experts?  What are "killing fields"?  How many geometries can a region of the universe have?

On 12/23/2023 at 9:20 PM, Markus Hanke said:

Well, one must remember that Newtonian gravity is only a very simplified approximation that disregards all non-linearities, so it is perhaps not so surprising that some of its concepts turn out to be less general than we take them to be.

When GR says "general relativity does not offer a single definition of the term mass, but offers several different definitions that are applicable under different circumstances,"

does than mean that mass is different depending on how close to the speed of light it is traveling thru space?  If so, I don't see how that would impact the concept of a finite amount of mass in the universe.  You mean an expansion of matter, contained within space, is moving at relativistic speeds, through space, so we don't know how massive it is because we don't know how fast it is moving?

10 hours ago, Markus Hanke said:

What Genady means is that the universe is a curved spacetime, as described by General Relativity. The thing now is that some concepts we are used to from old Newtonian physics do not straightforwardly translate to GR - and “mass” is one of them.  The question of “what is the mass associated with a given region of spacetime” has no simple answer; there are in fact several different notions of mass that apply to different sets of circumstances, so it really depends.

The underlying reasons for this is that the gravitational field in GR is self-coupling and thus itself a source of gravity (unlike in Newtonian gravity); but this type of energy cannot be localised, and is frame-dependent, so it is difficult to account for in an observer-independent way.

Thanks for the info.  That is so strange and surreal.  This is from your link:

"...general relativity does not offer a single definition of the term mass, but offers several different definitions that are applicable under different circumstances. Under some circumstances, the mass of a system in general relativity may not even be defined."

That seems obvious and makes perfect sense.  Hahaha.

15 hours ago, Genady said:

Just to clarify, AFAIK, the concept of mass is not applicable to universe and thus it cannot be described as finite or infinite, regardless of the curvature.

That is an amazing thing to consider, and a very new concept for me.  How do you know that?  When it curves around it ends up on a different dimension or groove in the record?

On 12/14/2023 at 7:10 AM, TheVat said:

Not typical of my music tastes, but it's interesting to learn that a mystery regarding a background song on The X-Files has finally been solved after 25 years.  I remember the episode, but hadn't the slightest idea that a background song in a bar scene was specifically composed for the episode.  Or that it had an ET theme (the second video, at the end of the article, has the full track minus bar noise).

https://www.npr.org/2023/12/13/1219137444/x-files-missing-song-mystery-music-lost-media

Thanks for posting that.  I'm sure I saw every episode of X-Files, I just don't remember that part.  But good to hear it.  Dan Marfisi and vocal by Glenn Jordan "Staring At The Stars"

8 hours ago, Genady said:

Let me try to explain it with a bit of algebra.

In an expanding homogeneous isotropic universe, a distance between any two points - let's call them, galaxies - is proportional to a number, a(t) , called scale factor, which increases with time, t . So, for example, if a distance between some two galaxies at some moment is D then later, when a(t) is twice as large, the distance between these two galaxies is 2D . Thus, this distance increases with time as a(t)D .

If the universe is finite, then there is a largest distance in it, which, just like any other distance, is proportional to a(t) . Let's call it, a(t)L . The only way for the a(t)L to become infinitely large is that a(t) becomes infinitely large. But, if a(t) becomes infinitely large, then distance between any two galaxies, a(t)D , becomes infinitely large.

IOW, all galaxies become infinitely far from each other. We of course know that it isn't so. Thus, either the universe was finite and remains finite, or it was infinite to start with.

Good answer!  Thanks for the reply.

On 12/18/2023 at 9:10 AM, Genady said:

No, in a continuous process it cannot.

 

What is "number TREE3"?

Thank you

Whoops, I meant TREE(3).  They know it is finite, but I don't understand how they know that, since it blows past Graham's number like it's not even there.

Matter in the universe is probably finite, but maybe space by itself can stretch beyond that to infinity, assuming flat or hyperbolic universe?  A positively curved universe is certainly finite in mass and size.

Is "infinity," like a singularity, just an abstract idea?