Coffee, tea, and a dream

Herb and Stan meet for coffee later in the day.  Besides his part-time physics teaching, Herb also is trying to write fiction.  Stan brings up that subject after they sit down with their coffee—or in Stan’s case, hot tea.

“How’s the writing going?” Stan asks, after swallowing a sip of tea.

“Pretty much, it’s not going.  It’s stalled. Stuck.  I figure I’m not cut out for it.”  Herb takes a sip from his coffee and a bite of pumpkin bread and shakes his head.

“I figure everybody’s cut out for it, Herb,” Stan says with a tight-lipped smile, looking directly at Herb.   “It’s just a matter of whether you want to badly enough.”

“Well, okay,” Herb retorts, with exasperation in his voice.  “Maybe I don’t want to badly enough.  It’s all about betraying people.  If you want to write a good novel, you have to betray people, and the first person you betray is yourself, because you never thought you’d betray anybody!”

Stan calmly looks off into the distance, or actually at a good-looking girl sitting near the window, and raises one eyebrow as he takes another sip of tea.  After he sips, he says quietly, “I don’t care if you write about me, Herb.  And nobody else would care either, I bet.  They’re not even going to recognize themselves.  And what does it matter if they do?”

After thirty seconds of silent munching and not so silent sipping, Herb says, “All right, that’s enough about the writing thing.  I can take a class or something if I want to keep it going.  What about your space and time investigations?”

“Stalled like your novel.”

Herb laughs out loud.  “Well, I guess I shouldn’t feel too bad, then.  I’m not the only one who’s stuck.”

“Maybe I should take a class.  Or something.”

Herb chuckles at the joke, then sits up straight in his chair and holds his arms out at a 45-degree angle from his body.  “I’m here to help you!” he says boldly, with a big smile, causing a few concerned looks from the adjacent tables.  “I can give you the standard scenario. And actually you’ve helped me.  All I need is a little outside encouragement, and I can keep at it, so thanks.”  Herb takes the last bite of his pumpkin bread and pulls a legal pad out of his book bag.  “Did you do a drawing yet?”

“I started one, but I haven’t labeled it yet.”  Stan pulls two pieces of paper out of his notebook.  “Here’s the drawing, and the calculation I already did for the stationary streetlight case. I didn’t understand what you meant about the imaginary observer.”  Herb takes a look at the drawings, and points to the place where the imaginary observer is stationed.

“Well, you marked the spot, or at least you have an arrowhead there.  Here, let me mark it with an X, and label the times represented by the drawings.” Herb writes on the drawing 

  then says, “What you see first are identical scenes in the different rest frames, but with the arrows reversed.  So far so good, but nothing relativistic has happened yet.”  Herb pulls his chair up closer to the table, takes a sip of coffee, and says, “Now.  A rest frame is like a railroad track with the railroad ties evenly spaced, giving a measurable distance from wherever you are.  Okay so far?”

“So far as establishing spatial coordinates in each case, yes,” Stan says, looking at Herb, “But I still don’t see why you put the X where you did.  The light came from the streetlight, and the X is not at the streetlight.”

“Ahh,” croons Herb, putting his elbows on the table and looking Stan in the eye, “But where was the streetlight when it flashed?”

Stan looks down at the drawing, his lips pursed slightly.   Then he slowly smiles, although his lips still don’t part to show his teeth, and looks back up at Herb.  “X marks the spot,” he says, nodding in appreciation of what he’s just learned.

Herb nods along with Stan.  “Yep, you got it, Stanislaw, old bean.  That’s where the streetlight was when it flashed.  Then it moved the additional distance to the left while the light was traveling to the car.  In the street rest frame, it’s the car that travels that distance while the light is on its way from the streetlight.  But, according to the street rest frame, how far did the light travel to get to the car?”

“Farther, or further, than the car rest frame.  The car is moving away and light has to catch up with it.”  Stan sits back, takes a sip of tea, which he finds to be still warm enough to be enjoyable.  Herb is nodding and writing on the diagram.

“We now need labels for all the quantities in the diagrams, then the final step will be to relate them to each other—the times and the distances, in both rest frames.  How about if I give you some labels for the diagram and you see if you can find how they relate?”  Herb looks up at Stan and adjusts his black-framed glasses with his right hand.  His glasses are relics of the late 1960s that have come back in style again.  His hair, partially gray but still mostly black, is long and thick and pulled back in a ponytail..  His body is trim from bike riding and walking instead of driving a car. 

Stan, who has thin wispy blonde hair, no glasses, and is tall and lanky naturally, without exercising, asks Herb about his earlier experiment in the car, where he thought he determined the time of the flash of the streetlight:  “What about the time I measured, or calculated actually, early this morning for the flashing streetlight?  Is it right?”

Herb now purses his lips slightly, but stops when he realizes he’s imitating Stan.  “Well, actually, no.  Your time on your car clock is not synchronized with the street rest frame, and the distance you used is the street rest frame distance, too, instead of the X-marks-the-spot distance for your rest frame.  And the car odometer, using rolling tires as a way of measuring distance, is not something I’ve ever seen analyzed in relativity, by the way. It’s a tough thought experiment you’ve presented me with!”  Herb now looks toward the window where he, too, had noticed the good-looking girl, and is slightly disappointed to see she isn’t there anymore. He takes a final sip of his coffee, which he finds to be too cold to be enjoyable, and says, “At this point don’t worry about anything except the standard time you can find by doing the calculations for the car rest frame, using the diagram here and the labels I’m putting on it.  I’ll leave the distances as variables, so you don’t have to worry yet about how they’re measured.”

After he glances at the diagram, Stan looks up at Herb quickly, as he remembers something from earlier in the day.  “What about that dream you were having when I called you this morning?”

“Oh, yeh,” says Herb, with , “the one you interrupted at a crucial moment.”

“Sorry about that, but I hope you wrote it down.”

“I did, but I don’t have my journal, and I can’t recall specifics at the moment.  Except I was in a small motel room, and I was going outside and coming back in to look at myself in the mirror, and a small passenger train backed into the yard outside, and men and women dressed like postmen were passing by me in a hurry, not answering any of my questions, maybe because I didn’t have shoes on and was standing on the wet grass, trying to talk to them.”

“That’s pretty good for not recalling specifics.”

“Funny, isn’t it, how you think you can’t remember something, but once you start talking about it, it starts to come back.  Except that usually doesn’t happen with dreams.”

“What was happening when I woke you up?”

“I’d gone to another motel room, where there were two girls about 10 years old dressed up like women, in long dresses and wearing beaded necklaces.  The mother of one of the girls was standing at a mirror, dressed but still making some final adjustments.  She didn’t look at me.”

“Somebody you know?”

“Oh, yeh.  You know her too.”

“Your ex?”

“My most recent ex, yep. I hadn’t seen her or the girls for a long time, but it was like the time hadn’t passed, like we were all on a trip together.  I felt tongue-tied, as usual—”

“Not a problem you’ve ever had with me,” Stan interrupted.

 “Yeh, well, you like to talk about philosophical and physics questions, so that’s different.  You know small talk has never been my strong point.”

“I never gave it much thought …”

  “Anyway, I remember one of the girls saying something like ‘If I could have brought my dog’ but otherwise I can’t recall any conversation.  I put my hand on Denise’s shoulder, and felt the chiffon, or whatever it’s called, of her blouse, and then you woke me up.”

“Well, maybe it ended when it should have,” Stan said, putting his notebook back into his backpack on the table in front of him.

“You would take the positive view of your not very well timed call,” said Herb, smiling in spite of the serious tone of his voice.  After putting his legal pad back in his black book bag, he stands up and says, “Please wait until later in the morning to call me next time okay?”

“Sure, I promise I won’t call before 7 a.m. next time,” Stan says, getting up to go.

“How about if you make it 8 a.m.?” Herb says as they walk out the café door.

                “Eight a.m. it is—no earlier, I promise!”

                “Later!”  says Herb.

                “Later!”  Stan responds as they head off in opposite directions along the sidewalk.  A moment later Herb hears Stan mumble “not earlier” and then hears him start whistling “We’re Off to See the Wizard” as he turns a corner and moves out of hearing range.