CT Why didn't Obi Wan sense the destruction of Alderaan before it happened?

The Rise & Fall of Darth Vader - drawing from the ANH radio play.

The Rise & Fall of Darth Vader

"I think it's time we demonstrated the full power of this station," Tarkin said. Turning to Motti, he commanded, "Set your course for Alderaan."
"With pleasure," Motti replied with an evil smile.
Realizing what Tarkin intended, Vader surveyed the man with new respect. The Dark Lord had done many horrendous and unpardonable things, but it seemed that Tarkin- at least in this situation- was even more diabolically inventive. However, Vader had one problem with Tarkin's scheme. "Alderaan is one of the foremost of the inner systems," Vader said. "The Emperor should be consulted."
"Do not think to challenge me!" Tarkin snapped. "You are not confronting Tagge or Motti now! The Emperor has placed me in charge of this affair with a free hand, and the decision is mine! And you will have your information that much sooner."
Vader had long suspected that Grand Moff Tarkin was insane, but it was not until Tarkin had addressed him just then, without a trace of fear, that Vader was left without a doubt. Vader said "If your plan serves our purpose, it will justify itself."
"The stability of the Empire is at stake," Tarkin said. "A planet is a small price to pay."


Death Star

"I think it's time we demonstrated the full power of this station," Tarkin said. He looked back at his officer. "Set your course for Alderaan."
The man mumbled something and left, but Tarkin was already thinking ahead. If Princess Leia was a thorn in the Empire's side, then Alderaan was a forest of thorns.
Well, it was time to purge that forest. With fire.
Tagge started to say something but apparently thought better of it. Tarkin smiled almost benignly and said, "I understand your concerns, General. Rest assured I've spoken with Emperor Palpatine recently about demonstrating his battle station's range and strength. He has assured me that I have full rein to do so." He looked at Vader. "You disapprove, Lord Vader?"
"Not at all, Governor."

Yup:



Vader stared at the motley array of stars displayed on the conference-room map while Tarkin and Admiral Motti conferred nearby. Interestingly, the first use of the most powerful destructive machine ever constructed had seemingly had no influence at all on that map, which in itself represented only a tiny fraction of this section of one modest-sized galaxy.
It would take a microbreakdown of a portion of this map to reveal a slight reduction in spatial mass, caused by the disappearance of Alderaan. Alderaan, with its many cities, farms, factories, and towns -- and traitors, Vader reminded himself.
Despite his advances and intricate technological methods of annihilation, the actions of mankind remained unnoticeable to an uncaring, unimaginably vast universe. If Vader's grandest plans ever came to pass, all that would change.
He was well aware that despite all their intelligence and drive, the vastness and wonder were lost on the two men who continued to chatter, monkeylike behind him. Tarkin and Motti were talented and ambitious, but they saw things only on the scale of human pettiness. It was a pity, Vader thought, that they did not possess the scope to match their abilities.
Still, neither man was a Dark Lord. As such, little more could be expected of them. These two were useful now, and dangerous, but someday they, like Alderaan, would have to be swept aside. For now, he could not afford to ignore them. And while he would have preferred the company of equals, he had to admit reluctantly that at this point, he had no equals.

 

Iron_lord quoted

Realizing what Tarkin intended, Vader surveyed the man with new respect. The Dark Lord had done many horrendous and unpardonable things, but it seemed that Tarkin- at least in this situation- was even more diabolically inventive.

Sorry, but this is one thing I just don't buy. There is a thing called "body language" and what we saw in the actual film rather suggested that even Vader had not believed that Tarkin could seriously mean what he was about to suggest.

We can all observe that the otherwise relaxed, cool and generally hard to impress dark lord making a rather erratic head move the moment Tarkin announced:

TARKIN Perhaps she would respond to an
alternative form of persuasion.

Vader jerks his head around

VADER What do you mean?

It always (and still) looked to me, as if Vader had a pretty good idea what Tarkin was about to propose, but didn't really believe it and therefore asked for clarification.
His reaction was one of surprise, but apparently the author who came up with this conjecture has no explanation for Vader's erratic head movement.

 

The scene quoted begins right after Vader's "erratic head movement". Which the author doesn't mention, simply because head movements are just not that important.

Starting the scene a bit earlier:

Tarkin looked to Vader and said, "Perhaps she would respond to an alternative form of persuasion."
"What do you mean?" asked Vader.
"I think it's time we demonstrated the full power of this station," Tarkin said. Turning to Motti, he commanded, "Set your course for Alderaan."
"With pleasure," Motti replied with an evil smile.

The point being made is that Vader is surprised by just how ruthless Tarkin is.

 

Ah, but he did. Check out what Yoda says in "Voices".

YODA: "Speaking to the dead I was, friends long gone. Good friends."

But before then, Luke was barely conscious when he saw and heard Obi-wan. As noted in the script itself when Luke finally sees Obi-wan.

Luke looks toward the voice in amazement. Ben has materialized as a real, slightly shimmering image near Yoda. The power of his presence stops Luke.

Versus earlier in the film.

Luke lies face down in the snow, nearly unconscious. Slowly he looks up and sees Ben Kenobi, barely visible through the blowing snow. It is hard to tell if Kenobi is real or a hallucination.

 

We are talking about what happened in a film, not just a book or vague memories what did or did not happen in the actual film. Actors follow the instructions of the director, and I consider Lucas to be such a talented actor that he didn't let Prowse move the way he did in that particular scene just by accident.

That's retroactive continuity that tells me little to nothing what the 1980 film actually intended to convey. And it's pretty obvious that Luke doesn't think of the deceased like Kenobi, Aunt Beru, Uncle Owen or Biggs, but the living (Han and Leia) instead.

And obviously Yoda isn't surprised at all

LUKE I saw... I saw a city in the clouds. YODA Mmm. Friends you have there.

 

That's not what I'm talking about. Luke has his vision then because he has his vision. It isn't because of "Old friends long gone", but the future.

YODA: "It is the future you see."

"Old friends" refers to what the Force can allow a Jedi to see. Han and Leia are not long gone, but they're about to be put in danger. The "Old friends" is when Luke sees Obi-wan later on.

 

The point I was making was that what happened in the book was not at all incompatible with what happened in the movie - they had the radio play bonus scene line

"Alderaan is one of the foremost of the inner systems. The Emperor should be consulted."

and it was the author's job to figure out what Vader was thinking right before he said that line.