Questions on space and and stuff
 

Probably should know this stuff and the questions are ridiculous, but 2 hour commute everyday, passing NASA Ames, Stanford linear accelerator and an airport,..mind wanders...

1. Yesterday they announced the oldest galaxies ever observed, how come the oldest galaxies are the furthest away?

2. Does an airplane have to adjust its altitude due to the curvature of the earth?

3. How high do I have to jump so that I land in a different place because the earth would have rotated beneath me?

I only know the answer to the first one. It is due to the time it takes for the light to travel to us. So if something is 1 light year away ( a measure of distance) it takes the light 1 year to get to us from there and we are seeing it as it looked 1 year ago. Therefor if something is 14 billion light years away it took 14 billion years for the light to get to us from there and we are seeing it as it was 14 billion years ago. It probably no longer exists and definitely not as we are seeing it so in a way we are looking backwards into time.

I *think* the answer to #3 is along the lines of...you'd have to jump partially sideways to counteract the Earth's rotation, no matter how high you were getting. You don't stop rotating just because you're not touching the ground. Since you'd start the jump rotating (sorta kinda), you'd have that momentum.

The part I've never heard explained when they use this to date the universe is that if it's 14 billion years away, don't you also have to go backwards to include how long it took for it to GET 14 billion years away for the light to take that long to reach us?

On #2, gravity is always pulling the plane closer to the earth, and lift constantly changes not just with altitude but with weather. A pilot is constantly making little corrections that overcome these forces to stay at a roughly stable altitude.

#3 is definitely that you are being carried along with the earth, as is the air, so your error in landing is much less than any rotation effects.

The Doppler Effect/light shift. As an object moves away from us (remember, it's all relative), the light of that object will shift towards red. Objects moving closer will shift towards blue. So part of how they determine what's the oldest, is how far it's shifted towards red, which usually also ends up being the furthest away from us.


I'd say no. Why? My guess would be that because the earth is so big, that adjusting for the curvature of the earth isn't an issue.


I'm guessing pretty far. You are moving at the same speed as the earth is when you're on the ground and you are also held within its gravitational field. So you would have to, at the very least change the speed you are going (slower or faster) after you jump and somehow decrease the affects of earths gravitational pull. Of course you could just jump forwards or backwards and you would land in a different place. :)

I'm not an expert by any means, just guesses really, so I could be wrong. :)

I am pulling my responses out of my ass, so please wait for a qualified physicist/scientist to get the correct answers, but here are my best guesses...

1. This will be a support for the Big Bang Theory, the theory that the universe started as one infinitesimal point filled with mass, which then exploded (the Big Bang) and forced the universe to expand to make room. The theory states that the universe has been expanding ever since (but won't forever, it will eventually collapse back on in itself). The oldest galaxies are, of course, the first ones formed--forming right after the Big Bang and racing along ouward with the edge of the universe, which is far away from us and getting further...theoretically.

2. The plane would need to achieve escape velocity, I believe, to need to adjust. It appears to be going in a straight line, but the imaginary line it is following is actually travelling in a circle around the Earth. If the plane were to go fast enough to achieve escape velocity, it could escape Earth's gravity and would need to adjust its trajectory to achieve orbit (stay within Earth's gravity well and travel in a straight line).

3. Same concept as the plane. Although as a techncial answer to your question, if you somehow had the power to jump incredibly high and fast, you would eventually reach a point where escape velocity would fall below the speed you are jumping, and the Earth would move under you. Of course, you would then not actually fall back down to Earth, since you would have accepted its gravity well.

#2 falls under "The Great Circle route" idea

Since the shape of the earth is a sphere every path and aircraft takes through the atmosphere is actually a circular one. If you actually looked at a flat map with a flight path on it from say New York to LA, you'd see the plane flies in a circle and ends up passing over places like Detroit or Houston instead of traveling in what would seem like a straighter line by passing over places like st Louis or Kansas City. (cities are guesswork as I have no clue just how far deviated the actual circle might be)

http://en.wikipedia.org/wiki/Great_circle

#3 is a reference to newton's laws

A Body in motion tends to stay in motion. IE you are not sitting still and the earth is dragging you along. You are spinning just as fast as the earth is, so when you jump that lateral motion is still happening, you are simply in a different location relative to it. To do what you suggest would require that you apply a force to yourself that negates the rotational speed that you already have.

Think of it as a measuring stick that is 14 feet long and you can not see anything past 14 feet. There may well be something further at 15 or 16 feet but there has simply not been enough time passed for the light from it to reach us. We can basically look in every direction and see out to 14 billion light years but no further do to the fact that even if there is something further we have not received the light from it yet since not enough time has passed.

If we somehow instantly teleported a billion light years away to another planet we could look back on the Sun and Earth as it was a billion years ago and the now 14 Billion year old galaxies we see from Earth would look 13 billion years old instead and there would likely be newer 14 billion year old galaxies further past them that we can not yet see from Earth for another billion years. Basically like moving a foot to the left with your 14 foot tape measure and seeing new objects off to your left but no longer seeing the ones on the far edge to your right.

Thanks for all the answers.

I guess I am having a hard time wrapping my head around the time=distance thing. I don't see why we couldn't discover that the galaxy next to us is the oldest.

This is a fun thread.

The plane... whether a plane needs to adjust to maintain altitude depends on how it generates the force that counteracts Earth's gravitational pull. When you think about motion as the result of the combined forces an object is exerting / having exerted on it. To maintain altitude, any airborne object must exert a force of equivalent strength to G in the opposite direction of G. I don't know much of anything about aerodynamics, but I expect that at cruising altitude, it is not difficult to maintain a constant force to counteract gravity, since pilots have control over the shape of planes' wings and the air flow above and below the wings are responsible for whether any lift is generated.

As for the jumping question... theoretically, any jump off the surface of Earth should ever-so-slightly alter where you land, no? Newton's gravitational constant depends in part on the distance between two objects, so when anyone jumps even the smallest bit, the gravity between that person and Earth decreases the tiniest bit. Thus, someone in mid-air loses a tiny bit of the angular momentum that Earth generates for grounded objects as it continues to rotate, and the person lands nanometers behind their prior position on Earth relative to the direction of its rotation.

I don't think this is the current thinking anymore. Check out the video linked below. Sounds like the galaxies are all moving away from each other at increasing speeds. The video is an hour long, but I found it very informative for all levels of current science understanding.
http://www.youtube.com/watch?v=7ImvlS8PLIo

In a vacuum, it wouldn't matter since jumping "straight up" would include the rotational velocity of the earth. In the real world, any jump perfectly straight up would lead to a different landing spot due to the friction of the air. I don't know how to do the measurement, but a normal human jump would probably see nanometers of displacement due to air friction.

Put a piece of masking tape on the floor. Stand on the masking tape and jump straight up. Keep doing this for 14 billion years and see if you end up in a different galaxy. I think that somehow answers two of the three questions right there.

For another interesting video, check out:
http://www.youtube.com/watch?v=FjAqcV_w3mc

Toward the end, he gives an example of how general relativity and special relativity affect ordinary people every day...by explaining how GPS works and how the calculations need to take into account relativity to accurately measure location. Again, very non-scientist friendly.

If you put that piece of tape on/in a plane, you'd cover all three.

Right on!

Next question!

?

Great thread.

I highly recommend Kip Thorne's "Black Holes and Time Warps" for reading.

I see your question there. I think there may be specific answers in that we have some idea how old the galaxies in our portion of the universe are, and where to look to find older galaxies.

But I think the more general answer is that a galaxy closer to us could be older, but that we don't really know that. Whereas if we look at a galaxy 14 billion light years away we *know* for certain that it existed 14 billion years ago. If we look at one 100 light years away, we can't be certain whether it existed 14 billion years ago. If that makes sense.

I imagine that they understand our neighborhood of the universe enough to not really need the second point, but I think it answers your question most directly.

Put that plane on a giant treadmill and this thread may never end.

I believe if you were to jump so high that you left the atmosphere of the earth, the vacuum of space would alter your speed enough that when you were to land, the spot from which you jumped would be a distance from which you would land. That is unless a satellite or some other object impeded your path, causing another unknown alteration of your orbit around the sun. The only problem then is that you would technically be outside of the point where the gravity of earth would bring you back down on its own. Of course it is unlikely you would get to experience the knowledge of your landing spot and the distance between the two points, as you would have died a long, long time before landing...

Now the proper time to contemplate all of this is best when, oh... i don't know...

Fascinating thread (except for the Pumpy Part).

Pumpy kills me.

Ok, some new ones:

I don’t understand how adding a retractable axel on the back of a dump truck distributes the weight. I love this video, but does not help-https://youtu.be/Ijvmd11WcJc

From my students: how many holes does a straw have?

0

I'd argue 1.

Though that's a god damn semantic nonsense question. :)

You can actually use god damn semantic nonsense to prove a straw has zero holes with a simple demonstration.

1) Take a straw and poke a hole in the side of the straw halfway between the two ends.
2) Attempt to use the straw normally and see how the hole in the side of the straw impedes proper use.
3) Ask your students why the straw isn't working and get the response, "There's a hole in the straw."
4) If a straw doesn't have zero holes to begin with, then why wasn't the students' answer, "There's a second (or third) hole in the straw?"

Covering up any one of the 3 holes would return the straw to a more proper functioning definition, correct?

If you covered up the introduced hole, sure. I would think that covering one of the ends would render the portion of the straw between the covered end and the introduced hole inoperable, so the proper functioning of the straw would already be compromised to a degree. The efficacy of the remaining portion would be determined by the location of the hole and where it lay in relation to the uncovered end. If both the uncovered end and the hole were above the fluid line, you've got a particularly useless flute, for example. If the hole is above the fluid line and the uncovered end is below the line, you would still have to turn your face sideways in relation to the straw to achieve any suction. Besides looking like a feeding vampire, this seems to be at best a juryrigged solution to the problem.

(God damn semantic nonsense time: how did I use the word 'hole' in my reply, and how does that relate to the number of holes in a functioning straw? :) )

Just when I think I understand, information like this turns my world upside down
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I actually have no clue what this meme is trying to say. None of it makes any sense.

It is not that the galaxy are moving, it is that the universe is expanding.

Think of two dots on a rubber sheet, then stretch it.
They will start close, but the longer you stretch it, the farther apart they get.

Alright AENewman. I think I've got a handle on what these are trying to say.

Where both of them fall flat is the relationship between relative motion, gravity, and how all that plays together.

When Felix goes up, he's still spinning with the rotation of the earth, the same as the atmosphere. The atmosphere also spins, but because of the sun, and the unequal heating of the earth surface we have pressure and temperature variations. High seeks low, warm air rises, cold air sinks, and so on. Also, the Coriolis effect impacts wind direction, speed and weather do to friction of the atmosphere against the spinning planet.

So as Felix ascends, he is still traveling the same speed as the earth because of gravity and rotational speed, however he doesn't keep pace with the planet because of weather and wind.

In the second box, let's break this out line by line.

-"If the earth was moving faster than sound"

This is wrong just from the start. The speed of sound is measured on the planet, already rotating, already spinning. You perceive no motion on the planet because you're so small in comparison to it. So this starts off with an incorrect supposition. One has nothing to do with the other.

"and the atmosphere moved with the earth"

It does, but with the caveat that I established earlier.

"Then you wouldn't see clouds moving"

See above.

"The fact that they do, proves that the Earth doesn't move with the atmosphere"

It's not an if/then statement. It proves nothing except a lack of understanding of physics and weather. Like I said above, it does, but we do have weather, gravity and wind friction with the surface that drastically slows down the wind.

"So planes/balloons should be affected by the alleged spin of the Earth"

They are, planes and balloons measure speed relative to the rotation of the earth, again, which you perceive to not be moving at all, so they move a lot. The speed of the earth is measured relative to a fixed point in space, far away from the planet, where rotation can actually be observed.

The graphic is exceptionally confusing to me. It's confusing because of the incorrect assumptions that it makes. It's all really bad, F level, 8th grade, Earth Science arguments.

Ugh. There are so many false assumptions built into that meme, it makes my head hurt.

Sometimes the world makes me sad. :(

+1

That makes me happy again. :)

Funny you should say "fall flat" i pulled them off a Flat Earth website. I was doing a lesson on social media and facts.

A key part of their argument is to deny basic principals of physics are not universal.

i very much appreciate your ability to articulate the answer. I had such a hard time wrapping my head around their flat earth thinking.

I've never understood the Flat Earther's endgame. "We never landed on the moon" or "Evolution/Dinosaurs/Fossils aren't real" I get where they're trying to go, but even if there was some massive conspiracy and the Earth really was flat what is that proving or changing?

Besides, Flat Earth is so 2016. Hollow Earth conspiracies are much cooler these days!

Just to be a technically correct smarta*! I would say, as high as you need to leave the ground. Remember that not only is the earth spinning, it is also moving in an ellipse around the sun as the solar system is moving too. Everything is in motion! woohoo!

My favorite smart ass thing to say is pointing out that you're never actually touching the ground, you're actually floating on it as your gravitational force pushes against the Earth's.

For those interested, I found the flat earth memes on this thread. Quite an interesting read, the flat earthed has managing to get all the other posters in a tissy
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I had big flashbacks to 1986. But seriously that was an impressive launch and smooooooooooooooth landing!

No kablooey!

The Space Capades starring Jeffy Bezo$ starts in 25 minutes!

My mistake...coverage til 9. Then the launch

If he dies then I call dibs on Amazon.

The Branson approach seems easier than a rocket.

certainly the engineers who designed the shape are having a big chuckle right now.

Purple Origin

I need to ask my old college roomy about that. He's been with Blue Origin since '03, works on the capsule.

For what he's trying to do, I agree. I'm curious how much of a tail tourist flights to space will have after the novelty of it wears off.