What is the newest installment of 'Random Thoughts' on Physics Forums?

[WWGD]

Don Kishon. From Wayne Newton.

 

[WWGD]

What ring of hell should we use for those who use no headphones for their audio, often at full volume?

 

[fresh_42]

What ring of hell should we use for those who use no headphones for their audio, often at full volume?

 

[WWGD]

Don't want to be a full hypocrit. I don't have my headphones with me now.

 

[WWGD]

Not sure which person is more likely to exist: A Theoretical Physicist or an Axiomatic Set Theorist.

 

[WWGD]

Interesting question( not mine; from a Math undergrad) " If I hit the Real line at random. How do I know I will always hit a number? I replied that the standard ordering < " less than" is dense in itself, i.e., if there are x,y with x<y, then there will always be a z with x<z<y. But this is not fully convincing, because the same is the case for Rationals x',y', but Rationals have gaps. I mumbled something to the effect of " That's why it's called the continuum, Reals satisfy the Lub- Completeness property.

 

[DrGreg]

If I hit the Real line at random. How do I know I will always hit a number?

It begs the question, what would it mean to "hit" a set without "hitting" a member of the set?

Or, to put it another way, what is the "Real line" if not the set of all real numbers?

 

[WWGD]

It begs the question, what would it mean to "hit" a set without "hitting" a member of the set?
Or, to put it another way, what is the "Real line" if not the set of all real numbers?

Yes, it's an issue of prumber? definitions. But some want " Something intuitive".

 

[WWGD]

Sorry, my( sadly new) phone is acting out.

 

[WWGD]

I guess Happy Persian new year to all.

 

[Astronuc]

Stumbled across a bit of trivia from a biographical note for George F Smoot,

My father had started a lumber business after the war to provide additional income. The business was successful, providing just enough for us to eke by. Then, a problem came up. In one of the stands of trees that my father purchased, a large, productive still was producing bootleg alcohol for this dry portion of the state. As soon as the tree cutting began, the group operating the still approached my father. They offered him cash not to cut the trees and expose their substantial operation. My father, at some personal risk, informed the police, and the trees were promptly impounded (no longer allowed to be cut for the saw mill) by the judge handling the case. He was apparently on the payroll of the illegal distillery operation as some police must have been. This caused an immediate financial crisis for us, as much of the saw mills/lumber company funds were tied up in trees, which were to be cut down and then milled to lumber and sold. Suddenly there was a shortage of trees to mill. Needless to say, our lumber company was soon in bankruptcy.

https://www.nobelprize.org/prizes/physics/2006/smoot/biographical/

 

[Borg]

Until recently, there were Smoot Lumber stores in the northern Virginia area. I've been there because they sold wood products that you couldn't find anywhere else. It appears that they were bought by another company but still have the Smoot name on the website. Seems to be quite a coincidence in names and trades.

 

[nuuskur]

Thesis complete. Defense in June. 4 years flew past quick

 

[WWGD]

Wonder if a topic for a Math thesis in the 15th century would be along the lines of ( in Latin)" On the solution set of x+1=2"

 

[WWGD]

Congratulations, @nuuskur . May you tell the general topic?

 

[nuuskur]

Congratulations, @nuuskur . May you tell the general topic?

Semigroups, categories, Morita equivalence.

 

[fresh_42]

Semigroups, categories, Morita equivalence.

And before you all start looking it up ...

https://ncatlab.org/nlab/show/Morita+equivalence

 

[Astronuc]

A large Navy research vessel that once belonged to late Microsoft billionaire Paul Allen tipped over — injuring 33 people — and is stuck at a 45 degree angle

https://www.yahoo.com/news/large-navy-research-vessel-once-214227909.html

The 3,000-ton ship was originally funded by Microsoft co-founder Paul Allen, who bought the then-offshore service vessel in 2016 and had it retrofitted to serve as an underwater research and exploration vessel. Allen hoped the boat would serve to scan the ocean's depths and locate historic shipwrecks and explore underwater ecosystems.

During its service years, the Petrel discovered several lost shipwrecks, including the USS Hornet and the USS Lexington, two significant US aircraft carriers that were sunk in World War II.

 

[fresh_42]

The first time someone did not use this misleading model of a balloon for our universe. He described it as a 3d-lattice instead where the points are the galaxies and the lines are all expanding. This is far better since every galaxy aka lattice point is the center of expansion. No more "center" was needed, and the big bang took place everywhere.

Why don't they still use this ballon metaphor?

 

[Tom.G]

Why don't they still use this ballon metaphor?

Who is going to do, or read, a Doctorate Thesis on a balloon?

 

[WWGD]

Doesn't @phinds include a balloon analogy in his posts?

 

[Ibix]

The first time someone did not use this misleading model of a balloon for our universe. He described it as a 3d-lattice instead where the points are the galaxies and the lines are all expanding. This is far better since every galaxy aka lattice point is the center of expansion. No more "center" was needed, and the big bang took place everywhere.

Why don't they still use this ballon metaphor?

You can draw the 2d version of such a grid on the surface of a balloon or on a flat sheet of rubber, which is a passable model for a spatial slice of the positive and zero spatial curvature FLRW spacetimes. I gather that a 2d Euclidean surface with constant negative curvature cannot be embedded in a 3d Euclidean space (or possibly it can be done but it intersects itself, I don't recall), so there's no great analogy for that.

The 3d grid you're imagining can only represent the curvature of the space in which it's embedded. That's either a flat Euclidean space or a spatial slice of our real spacetime, whatever that is.

While the latter is necessarily a correct model, it's probably not that helpful an analogy. It reminds me of an episode of the old radio comedy series The Goon Show where they travel to Paris. They decide to look at a map, which is followed by paper rustling sounds for about ten seconds, a pause, and then Peter Sellars' voice in the distance saying "Big, isn't it?" They have to take a taxi to meet up again.

 

[phinds]

Doesn't @phinds include a balloon analogy in his posts?

Yes

 

[dlgoff]

Now it's 33°F.

Well, it's a little warmer at 41 degrees. Still not what spring should be like. :(

 

[Klystron]

Well, it's a little warmer at 41 degrees. Still not what spring should be like. :(

Chilly here in the high desert at 58 degrees F.

I was heading outdoors to poolside to exercise prior to the anticipated 1 April opening of swim season, but decided to workout indoors until the cloud cover dissipates.

 

[dlgoff]

Chilly here in the high desert at 58 degrees F.

That IS chilly for where you're at.

 

[Klystron]

That IS chilly for where you're at.

Friends and neighbors told me at lunch this week that 2023 March has been the coldest in Las Vegas Valley in many decades. We locals wore sweaters and fleece -- equivalent to puffy parkas in colder climates -- over cotton layers and long pants. Even my friends from Nova Scotia felt chilly.

Our host suggested this cold Spring presages hotter-than-average Summer temperatures.

 

[dlgoff]

Our host suggested this cold Spring presages hotter-than-average Summer temperatures.

Bold by me.
That sounds good to me right now.

 

[WWGD]

Interesting question( not mine; from a Math undergrad) " If I hit the Real line at random. How do I know I will always hit a number? I replied that the standard ordering < " less than" is dense in itself, i.e., if there are x,y with x<y, then there will always be a z with x<z<y. But this is not fully convincing, because the same is the case for Rationals x',y', but Rationals have gaps. I mumbled something to the effect of " That's why it's called the continuum, Reals satisfy the Lub- Completeness property.

I meant to say, if you're given the Reals axiomatically, how would you tell the Real line is a valid model for them.

 

[gmax137]

Bold by me.
That sounds good to me right now.

Drove to Vegas yesterday from home near Reno. Saw a few snowflakes while in Red Rock Canyon this afternoon, that's a first.