nomesane?
The weather here sometimes mimics the human mind, mine anyway, and is doing this morning as fog closes in. What to think about, like a ghost ship cutting slowly through the soup,
ideas slipping away as quickly as they came, and no retrieving them. If you don't know what I'm talking about, you will soon enough. This
was the first view from bed as we sipped first cups of coffee this morning; not early, after six o'clock, as for a change we didn't turn out the light until after ten o'clock last night.
What am I contemplating? a video of naval exercises in which the former USS Ingraham, a warship, is cut in two and immediately sinks,
which is the idea of a torpedo that detonates beneath a ship's keel, creating a hole for the ship to drop into, instead of slamming into the hull.
Ships' crews often have "brotherhood" associations that maintain connections for years, decades after service, and sometimes reunions (my earliest Navy friend from OCS in 1957, Ray Barnes, enthusiastically kept up with his destroyer crew members from 1958 until his death in 2016), and seeing the ship decommissioned and later destroyed can be traumatic. I expect it was so for the crew of Ingraham.
My first ship, USS Corry, a destroyer, duty that I loved so dearly as enthusiastically to "augment" USNR to USN as a lieutenant (jg) and stay until I realized all the Navy was not like my first sea duty, was later sold to, as I recall, the Greek navy. A destroyer of her class is now a museum somewhere on the east coast, I think Rhode Island, but not sure, and I'd love to go aboard and reminisce. The USS Tripoli, that I've recalled here, was far different sea duty for me, during the Vietnam War, long separations from beloveds and encountering some miserable horses asses, and helped me work patiently toward completion of twenty years and retire. I couldn't care less about that ship's fate. Here's her picture, after decommissioning, being towed out of San Diego harbor.
But my main early reading today was about drone refueling of Navy aircraft carrier planes, is that real?
Lots has happened since I retired from the Navy soon 44 years ago. Do I miss it? no, and if I ever should, all I need to do is telephone USAA to hear them say respectfully, "Good morning, Commander Weller" and I'm back aboard.
The mind wanders, doesn't it, floats, doesn't it, drifts in and out of the fog. Nomesane?
See, it's Monday, no sermon to prepare again for several weeks yet, so I'm sitting here in my chair by the Bay, looking off into infinity (endless space), or eternity (endless Time).
Last night I came across two old photographs of classroom, schoolchildren saluting the flag
as we did it every morning my first year or two at Cove School. We started with our right hand over our heart (or in a military salute), "I pledge allegiance TO THE FLAG" - - and as we said "to the flag" we stretched our right arm out, hand pointing at the flag - - "of the United States ...".
There's another. With the window open (no HVAC in those years) and the steam radiator, the top one could well have been us at Cove School! Or the second one, schoolchildren at an outdoors assembly. You can sort of period-date them by the school building and the children's dress, hairstyles. The outstretched hand as part of our salute to the flag was suddenly stopped as we went into World War Two and it was clear that our salute was identical to the fascist salute of our deadly enemies the Germans and Italians. Maybe Robert will remember that, or Carl.
Breakfast: steamed shrimp from Tarpon Dock Seafood. Coffee black. Water cold.
In the beginning, God said "Let there be ..." and it was so. Heilsgeschichte, my lifelong special favorite of any number of creation stories, including two from Genesis that show not literal history as some insist, but how important we are to God. As mature Christians, it's important we recognize differences between holy stories and ongoing scientific exploration of the universe, the Creator's creation, with the wits given to us as humans in godly image. So, mindful that a thinking person can hold opposite beliefs in tension, and leaving kindergarten Sunday school to the literalist inerrantists, here's my best theological reading for last evening. See what you think:
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What Is Time, And Why Does It Move Forward?
Posted by
EarthSky Voices
September 19, 2021
We think of the universe as having a timeline, a point at which it began, until now. But how much do modern cosmologists really know about time? Image via Alex Mittelmann/ Wikimedia.
What is time?
By Thomas Kitching, UCL
Imagine time running backwards. People would grow younger instead of older and, after a long life of gradual rejuvenation – unlearning everything they know – they would end as a twinkle in their parents’ eyes. That’s time as represented in a novel by science fiction writer Philip K. Dick but, surprisingly, time’s direction is also an issue that cosmologists are grappling with.
While we take for granted that time has a given direction, physicists don’t: most natural laws are “time reversible” which means they would work just as well if time was defined as running backwards. So why does time always move forward? And will it always do so?
Does time have a beginning?
Any universal concept of time must ultimately be based on the evolution of the cosmos itself. When you look up at the universe, you’re seeing events that happened in the past – it takes light time to reach us. In fact, even the simplest observation can help us understand cosmological time: for example, the fact that the night sky is dark. If the universe had an infinite past and was infinite in extent, the night sky would be completely bright – filled with the light from an infinite number of stars in a cosmos that had always existed.
For a long time, scientists, including Albert Einstein, thought that the universe was static and infinite. Observations have since shown that it is in fact expanding, and at an accelerating rate. This means that it must have originated from a more compact state that we call the Big Bang, implying that time does have a beginning. In fact, if we look for light that is old enough, we can even see the relic radiation from Big Bang – the cosmic microwave background. Realizing this was a first step in determining the age of the universe (see below)
.
Relativity
But there is a snag, Einstein’s special theory of relativity shows that time is … relative: The faster you move relative to me, the slower time will pass for you relative to my perception of time. So in our universe of expanding galaxies, spinning stars and swirling planets, experiences of time vary: Everything’s past, present and future is relative.
Why the night sky can tell us a fair bit about time. Image via Arches National Park/ Flickr.
It turns out that because the universe is on average the same everywhere, and on average looks the same in every direction, there does exist a cosmic time. To measure it, all we have to do is measure the properties of the cosmic microwave background. Cosmologists have used this to determine the age of the universe: its cosmic age. It turns out that the universe is 13.799 billion years old.
Time’s arrow
So we know time most likely started during the Big Bang. But there is one nagging question that remains: what exactly is time?
To unpack this question, we have to look at the basic properties of space and time. In the dimension of space, you can move forwards and backwards; commuters experience this everyday. But time is different, it has a direction, you always move forward, never in reverse. So why is the dimension of time irreversible?
This is one of the major unsolved problems in physics.
To explain why time itself is irreversible, we need to find processes in nature that are also irreversible. One of the few such concepts in physics (and life!) is that things tend to become less “tidy” as time passes. We describe this using a physical property called entropy that encodes how ordered something is.
Imagine a box of gas in which all the particles were initially placed in one corner (an ordered state). Over time they would naturally seek to fill the entire box (a disordered state) – and to put the particles back into an ordered state would require energy. This is irreversible. It’s like cracking an egg to make an omelette. Once it spreads out and fills the frying pan, it will never go back to being egg-shaped. It’s the same with the universe: as it evolves, the overall entropy increases.
Increasing disorder
It turns out entropy is a pretty good way to explain time’s arrow. And while it may seem like the universe is becoming more ordered rather than less – going from a wild sea of relatively uniformly spread out hot gas in its early stages to stars, planets, humans and articles about time – it’s nevertheless possible that it is increasing in disorder. That’s because the gravity associated with large masses may be pulling matter into seemingly ordered states – with the increase in disorder that we think must have taken place being somehow hidden away in the gravitational fields. So disorder could be increasing even though we don’t see it.
But given nature’s tendency to prefer disorder, why did the universe start off in such an ordered state in the first place? This is still considered a mystery. Some researchers argue that the Big Bang may not even have been the beginning, there may in fact be parallel universes where time runs in different directions.
Will time end?
Time had a beginning, but whether it will have an end depends on the nature of the dark energy that is causing it to expand at an accelerating rate. The rate of this expansion may eventually tear the universe apart, forcing it to end in a Big Rip; alternatively, dark energy may decay, reversing the Big Bang and ending the universe in a Big Crunch; or the universe may simply expand forever.
But would any of these future scenarios end time? Well, according to the strange rules of quantum mechanics, tiny random particles can momentarily pop out of a vacuum, something seen constantly in particle physics experiments. Some have argued that dark energy could cause such “quantum fluctuations” giving rise to a new Big Bang, ending our time line and starting a new one. While this is extremely speculative and highly unlikely, what we do know is that only when we understand dark energy will we know the fate of the universe.
So what is the most likely outcome? Only time will tell.
Thomas Kitching, Lecturer in Astrophysics, UCL
This article was originally published in The Conversation. Read the original article.