yor_on

It's about what size of strudel you can fit in a room 50 m. long. Our friend Albert uses speed to contract his 500 m strudel. The other guy just measure and bakes a strudel to the rooms size..
.. A...

" Albert has installed two doors. Let's call them front door F and back door B.

1. Albert first accelerates the strudel outside of the throne room to such a speed that its length as measured from the stationary point of view is 50 meters.

2. The strudel enters through the back door B.

3. When the back of the strudel B_S is at the back door B, he orders someone to close the back door B. Since the strudel appears to be 50 meters long, its front end F_S is precisely at the front door F.At this moment it is clear that his strudel fits in the throne room.

4. In order not to damage the strudel, he orders someone to open the front door F,

5. catch the strudel and show that its length is 500 meter, which is 10 times bigger than Arthur the Muscle's strudel.

Conclusion: Albert the Smart wins the competition. "
-------------------------------------------------------------------------------------
You did notice that a short moment both doors was closed, and the strudel did fit.
Now if we had a observer who was bound and gagged :) to the strudel traveling he would see a different story.
-------------------------------------------------------------------------------------
. B ...

" Since he is moving with a very high speed (remember, the room is very short for him), he sees that Albert's order to open the FRONT door came right in time, exactly when the front edge of the strudel touched the front door F; however, the BACK door was still wide open © for him. It remains open until the whole strudel moves across the throne room, and the order to shut the back door comes when the back end of the strudel is in the room.

Notice: For an observer stationary in the throne room, at least one door is always closed, and both of the doors are never opened simultaneously. On the other hand, for the observer tied to the strudel, there is a time slot when both of the doors are open (giving him enough time to get through the room). "

---------------------------------------------------------------------------------------

Now what gives me the fits is that, let's imagine both have a film camera ok.
A:s film shows both doors closed and the strudel stuck in between the doors.
But B:s film will under no circumstances according to this show both doors closed with the strudel stuck in the middle?

In fact we could talk about two different universes here :) But both B and A (if longlived enough) can meet in the same timeframe 'later' on and exchange their films.
Any one care to comment this behavior :)

Not their meeting up i mean, but why bake a strudel that long? Noo, i mean, how is it possible for both to have so totally different evidence from the same localization?
Is this story correct or not?
mggb2001
yor_on,

I read this over a couple times and went to my textbook to look for a reason that would explain this apparent contradiction.

Your story seems perfectly valid and the only analogy that I could think of to explain would be the following:

It's a stormy night and there are lightning strikes going off like crazy.
You are standing next to a railroad track and a train is approaching.

You take out your camera and take a snap shot as the train goes by. Just as you take the picture the train is struck in the front and back end by lightning, simultaneously.

Coincidentally someone on the train has there video camera out and they happen to capture the event from inside the train.

When the video is reviewed, it show that the lightning hit the front end of the train first and then a second lightning strike hit the back end.(Assuming the train is travelling fast enough for this difference to be noticeable)
Though the two of you have contradicting evidence, they are both correct from their respective reference frames.

This comes from Einstein's thought experiment on simultaneity.

Someone tell me if this analogy applies to yor_on's story.

mggb2001
mggb2001
Just to add for further clarification, this comes directly from my textbook regarding the above analogy:

"This disagreement, however, depends on the transit time of light to the observers and , therefore, does not demonstrate the deeper meaning of relativity.
In relativistic analyses of high-speed situations, relativity shows that simultaneity is relative even when the transit time is subtracted out."

Hope this helps,

mggb2001
yor_on
Ok, but when was both doors simultaneously closed for B.
Can you see my headache now, slowly building ::))

Even when considering different 'timeframes'. At some 'time' for A the doors are closed, now i would call that a 'event' that is, something 'happens'. In B:s world it never takes place. You can see it as a relativistic effect but for me it seem to imply other things too :)

Ps: But Hey, it's no stranger than our ability to perceive timeless photons in midair i guess. If they had restmass we would be dead before ever seeing them :)
Sapo
I don't know that it doesn't happen the way you postulate, but it isn't intuitive, certainly. The observer on the Strudel looks ahead to see the door open, and then looks back to see the door closing. Even if he looks back at the same time, like Janus, he still sees _his_ world view at that instant. Because his time is compressed relative to the room, he will still see the doors open consecutively.

Oh, Lord. Did I pass the idiot test?
Ron
Hi guys,
Very cool and frequently discussed topic in SR. Read the thread (poll) about whether time dilation is real. It has alot of similarities to your topic.
Peace,
Ron
yor_on
yeah, it's possible to read it like you did :) Sapo. But as far as i understand it's not that way. For one observer there will be a time when both doors are closed simultaneously. For the other there will be no such event as i understand the text. So i wonder, is this a correct interpretation or not (the text you've been reading about the strudel :). And if it's only me seeing some strange implications here i wonder wonder why, as the lyrics goes :)
Sapo
Cool. Now I have a headache, too.
yor_on
PhysOrg scientific forums are totally dedicated to science, physics, and technology. Besides topical forums such as nanotechnology, quantum physics, silicon and III-V technology, applied physics, materials, space and others, you can also join our news and publications discussions. We also provide an off-topic forum category. If you need specific help on a scientific problem or have a question related to physics or technology, visit the PhysOrg Forums. Here you’ll find experts from various fields online every day.