What if? A sort of philosophical question.

[Medusa]

I'm going to look that one up. The goldfish example sounds interesting.

Ooo, it really is. I'd be interested in your opinion.

 

[Medusa]

Ooo, it really is. I'd be interested in your opinion.

I'd really like to get you in a Zoom Meeting where we could talk this stuff through using only what is in our minds at the time, no internet aids. Would be fun and you have me at a disadvantage on this particular stage as you have a wider knowledge base.

 

[Magna-Carta]

Here is a thought experiment that has been around for quite awhile.

Suppose you wake up tomorrow and everything in the universe has doubled in size. Would you be able to tell the difference? What does it say about our ideas about what is real?

For now I perceive this to be more of an analogy than a thought experiment. The continuation of the discussion from your post here has gone in a direction that I think is relevant, but for me only in that I see the question posed as a simple analogy.

My thoughts on it, rightly or wrongly, is that a thought experiment would take me in a completely different direction, which would then cause me to say we would notice a difference, based on some changes that I 'believe' would be observed.

 

[Medusa]

For now I perceive this to be more of an analogy than a thought experiment. The continuation of the discussion from your post here has gone in a direction that I think is relevant, but for me only in that I see the question posed as a simple analogy.

My thoughts on it, rightly or wrongly, is that a thought experiment would take me in a completely different direction, which would then cause me to say we would notice a difference, based on some changes that I 'believe' would be observed.

Can you elaborate a bit here (if you feel like it, of course) ?
How is an analogy much different than a thought experiment? I mean, I know they can be different, but also the same, in many ways.
What differences would you notice were you to think of this as an experiment?

 

[Medusa]

If we do not believe something exist doesn't exist for us

I like this concept because it's enticing and provocative to entertain. And, I think it's true to a great extent, even in real-world application; people refuse to "see" things all the time and so they simply don't. That's largely similar, I think.

 

[Magna-Carta]

Can you elaborate a bit here (if you feel like it, of course) ?
How is an analogy much different than a thought experiment? I mean, I know they can be different, but also the same, in many ways.
What differences would you notice were you to think of this as an experiment?

Well the question was, “Here is a thought experiment that has been around for quite awhile. Suppose you wake up tomorrow and everything in the universe has doubled in size. Would you be able to tell the difference?”

My initial thought was, no we wouldn’t notice, because everything would be relative, including ourselves in it. But then I thought, from a “thought experiment” point of view, that my own answer doesn’t do the thought experiment justice. I felt there is far more to thought experiments than basing my answer on an initial “visual sense” of the universe and everything in it being doubled in size. It could be said that I have over thought it. If that’s the case, then what’s the point of a thought experiment? Should the original question be called something else instead of a thought experiment? The question, to me at least, wasn’t entirely clear on what, “Would you be able to tell the difference?” meant. Tell the difference just simply visually, or otherwise?

Here goes:
If everything in the universe had doubled, wouldn’t then that also mean that the distance between objects in the universe has also doubled? Because if distances hasn’t doubled, then the Moon as it looks from Earth would look significantly bigger due to doubling in size. In order to not notice the doubling of size, the distance between the Moon and Earth would also have to be doubled. That seems to make sense to me.

I thought that would then include the doubling of the Sun’s distance from the Earth. Double the size of the Sun and Earth; the distance between them would also have to be doubled so that we wouldn’t notice the size increase. I’m sure that most of us know that it takes a little over 8 minutes for Sun’s light to reach the Earth. Doubling that distance would mean that it will then take 16 minutes to reach Earth. When we watch the sun setting , we are watching it disappear below the horizon as it was 8 minutes ago. If the Sun/Earth distance was doubled we would see the setting sun as it was 16 minutes ago. Someone would notice, as we would see a time difference of the setting Sun from the previous day, before the doubling in size. If most people didn’t notice, I would like to think astronomers would notice. So in answer of would we notice if the universe and everything in it doubled, I would say yes, from our other senses that somthing has change, and probably from daily on going mesurements that astronomers might already do on a daily basis.

Then just take the Earth that has suddenly doubled in size. To make it simple, I thought that if you take a cube and double its length, width, height, you have multiplied its mass by a factor of 8. Apply that to the Earth; increase the mass of earth by a factor of 8 based on it doubling in size. Then by what factor has the Earth’s gravity been increased by? Even if we as humans have doubled in size yet not visually noticed, would we notice the significant increase in gravity upon ourselves? How much more energy would be required for a rocket to reach escape velocity due to increased gravity? Would we notice that? As I say, if I’ve over thought it, then it might be because I’ve misinterpreted this Thought Experiment. At what point is a thought experiment scheduled to stop?

I could go on, just from my own thoughts. The surface of the earth rotates at a given speed. Double the radius of Earth and the surface of the Earth is moving faster, even for the same one rotation per day. I thought combine that with the sea water volume that would have also increased. I thought there will be significantly more Heat Energy in the sea for any given sea temperature. Heat and temperature being two different things. The speed of the surface of the earth and sea temperatures playing a major part in driving the Earth weather. Would we notice the difference in the Earths weather? I can go on further with other things we would notice, but I’m even beginning to boar myself. So is the original question posed just as a simple analogy (or some different appropriate word), or is it a thought experiment, which in my mind at least doesn’t necessary have an ending until the thought experiment is exhausted?

 

[Medusa]

Well the question was, “Here is a thought experiment that has been around for quite awhile. Suppose you wake up tomorrow and everything in the universe has doubled in size. Would you be able to tell the difference?”

My initial thought was, no we wouldn’t notice, because everything would be relative, including ourselves in it. But then I thought, from a “thought experiment” point of view, that my own answer doesn’t do the thought experiment justice. I felt there is far more to thought experiments than basing my answer on an initial “visual sense” of the universe and everything in it being doubled in size. It could be said that I have over thought it. If that’s the case, then what’s the point of a thought experiment? Should the original question be called something else instead of a thought experiment? The question, to me at least, wasn’t entirely clear on what, “Would you be able to tell the difference?” meant. Tell the difference just simply visually, or otherwise?

Here goes:
If everything in the universe had doubled, wouldn’t then that also mean that the distance between objects in the universe has also doubled? Because if distances hasn’t doubled, then the Moon as it looks from Earth would look significantly bigger due to doubling in size. In order to not notice the doubling of size, the distance between the Moon and Earth would also have to be doubled. That seems to make sense to me.

I thought that would then include the doubling of the Sun’s distance from the Earth. Double the size of the Sun and Earth; the distance between them would also have to be doubled so that we wouldn’t notice the size increase. I’m sure that most of us know that it takes a little over 8 minutes for Sun’s light to reach the Earth. Doubling that distance would mean that it will then take 16 minutes to reach Earth. When we watch the sun setting , we are watching it disappear below the horizon as it was 8 minutes ago. If the Sun/Earth distance was doubled we would see the setting sun as it was 16 minutes ago. Someone would notice, as we would see a time difference of the setting Sun from the previous day, before the doubling in size. If most people didn’t notice, I would like to think astronomers would notice. So in answer of would we notice if the universe and everything in it doubled, I would say yes, from our other senses that somthing has change, and probably from daily on going mesurements that astronomers might already do on a daily basis.

Then just take the Earth that has suddenly doubled in size. To make it simple, I thought that if you take a cube and double its length, width, height, you have multiplied its mass by a factor of 8. Apply that to the Earth; increase the mass of earth by a factor of 8 based on it doubling in size. Then by what factor has the Earth’s gravity been increased by? Even if we as humans have doubled in size yet not visually noticed, would we notice the significant increase in gravity upon ourselves? How much more energy would be required for a rocket to reach escape velocity due to increased gravity? Would we notice that? As I say, if I’ve over thought it, then it might be because I’ve misinterpreted this Thought Experiment. At what point is a thought experiment scheduled to stop?

I could go on, just from my own thoughts. The surface of the earth rotates at a given speed. Double the radius of Earth and the surface of the Earth is moving faster, even for the same one rotation per day. I thought combine that with the sea water volume that would have also increased. I thought there will be significantly more Heat Energy in the sea for any given sea temperature. Heat and temperature being two different things. The speed of the surface of the earth and sea temperatures playing a major part in driving the Earth weather. Would we notice the difference in the Earths weather? I can go on further with other things we would notice, but I’m even beginning to boar myself. So is the original question posed just as a simple analogy (or some different appropriate word), or is it a thought experiment, which in my mind at least doesn’t necessary have an ending until the thought experiment is exhausted?

I think what you've just done here is the definition of the exercise of a thought experiment.
And that your thoughts on the subject are interesting.

However, I interpreted the question differently in that I didn't understand it to be encompassing only visual perception, but engaging all the senses.

As for the distance between things; again I understood the question to mean everything has doubled (though it does specify size and I'm not sure space is a thing -- is it?). So, that was not a issue for me either.

I think the spirit of the question is to assume everything has doubled and you would be experiencing that reality with all your senses as you do now with your current one.

 

[Magna-Carta]

I think what you've just done here is the definition of the exercise of a thought experiment.
And that your thoughts on the subject are interesting.

However, I interpreted the question differently in that I didn't understand it to be encompassing only visual perception, but engaging all the senses.

As for the distance between things; again I understood the question to mean everything has doubled (though it does specify size and I'm not sure space is a thing -- is it?). So, that was not a issue for me either.

I think the spirit of the question is to assume everything has doubled and you would be experiencing that reality with all your senses as you do now with your current one.

I thought that if the doubling of space/distance wasn't a thing to be included, then it would have been very obvious to me that something had changed. Because objects, planets, stars, moons would/will look bigger if there distance away wasn't doubled as their size was doubled.

@oldlongwalker said “Suppose you wake up tomorrow and everything in the universe has doubled in size”, so for me I included everything. Including thinking about wavelengths of light. (Light wavelengths being something I’ve already mentioned somewhere here) I thought that if the wavelengths of light were also doubled, then we would then see colour differently.

I also considered doubling the speed of light, as in doubling everything. But for me at least I then saw that as being a constant, so I ruled it out. In that I believe (personal opinion) that the speed of light in itself isn’t a speed limit. But perhaps there is something about the universe itself that is or has the speed limit of 186,282.397 miles a second within it (a number that I’ve posted previously in a different thread as being my favourite number.) In that nothing can travel faster than 186,282.397 miles a second, ‘including’ light. Hence the reason why I said the visual timing of the sunset would be differnt to.

UPDATE:
Would tides be different too -- something noticeable? Due to the increased doubling of size of the moon, due to its then 8 fold increase of the moon mass.

Another thing I wondered about was the doubling of size of atoms, and therefore its atomic weight. Would that cause different kinds of chemical reaction? I personally don’t know, it was just a thought.

 

[oldlongwalker]

I thought that if the doubling of space/distance wasn't a thing to be included, then it would have been very obvious to me that something had changed. Because objects, planets, stars, moons would/will look bigger if there distance away wasn't doubled also.

@oldlongwalker said “Suppose you wake up tomorrow and everything in the universe has doubled in size”, so for me I included everything. Including thinking about wavelengths of light. (Light wavelengths being something I’ve already mentioned somewhere here) I thought that if the wavelengths of light were also doubled, then we would then see colour differently.

I also considered doubling the speed of light, as in doubling everything. But for me at least I then saw that as being a constant, so I ruled it out. In that I believe (personal opinion) that the speed of light in itself isn’t a speed limit. But perhaps there is something about the universe itself that is or has the speed limit of 186,282.397 miles a second within it (a number that I’ve posted previously in a different thread as being my favourite number.) In that nothing can travel faster than 186,282.397 miles a second, ‘including’ light.

If all the planets doubled in size and their distances shrunk accordingly, then there would be an obvious difference. If the distances remain the same, and the planets double, you wouldn't be able to tell. Light would also still be the same speed since that is a constant.

The main point is to suggest a scenario where you could have a change in the objects of perception which we would be unable to determine. In that way, it seeks to cast doubt on seeing itself changing the objects of perception.

 

[palides2021]

There is a terrific site called https://www.jstor.org/ where you can set up a free login and get access to the journal I mentioned and scores of other journals across every discipline.

I use JSTOR all the time and refer my students to it. We login through the university.

 

[palides2021]

If all the planets doubled in size and their distances shrunk accordingly, then there would be an obvious difference. If the distances remain the same, and the planets double, you wouldn't be able to tell. Light would also still be the same speed since that is a constant.

The main point is to suggest a scenario where you could have a change in the objects of perception which we would be unable to determine. In that way, it seeks to cast doubt on seeing itself changing the objects of perception.

Sounds like material for a sci-fi book.

 

[palides2021]

Well the question was, “Here is a thought experiment that has been around for quite awhile. Suppose you wake up tomorrow and everything in the universe has doubled in size. Would you be able to tell the difference?”

My initial thought was, no we wouldn’t notice, because everything would be relative, including ourselves in it. But then I thought, from a “thought experiment” point of view, that my own answer doesn’t do the thought experiment justice. I felt there is far more to thought experiments than basing my answer on an initial “visual sense” of the universe and everything in it being doubled in size. It could be said that I have over thought it. If that’s the case, then what’s the point of a thought experiment? Should the original question be called something else instead of a thought experiment? The question, to me at least, wasn’t entirely clear on what, “Would you be able to tell the difference?” meant. Tell the difference just simply visually, or otherwise?

Here goes:
If everything in the universe had doubled, wouldn’t then that also mean that the distance between objects in the universe has also doubled? Because if distances hasn’t doubled, then the Moon as it looks from Earth would look significantly bigger due to doubling in size. In order to not notice the doubling of size, the distance between the Moon and Earth would also have to be doubled. That seems to make sense to me.

I thought that would then include the doubling of the Sun’s distance from the Earth. Double the size of the Sun and Earth; the distance between them would also have to be doubled so that we wouldn’t notice the size increase. I’m sure that most of us know that it takes a little over 8 minutes for Sun’s light to reach the Earth. Doubling that distance would mean that it will then take 16 minutes to reach Earth. When we watch the sun setting , we are watching it disappear below the horizon as it was 8 minutes ago. If the Sun/Earth distance was doubled we would see the setting sun as it was 16 minutes ago. Someone would notice, as we would see a time difference of the setting Sun from the previous day, before the doubling in size. If most people didn’t notice, I would like to think astronomers would notice. So in answer of would we notice if the universe and everything in it doubled, I would say yes, from our other senses that somthing has change, and probably from daily on going mesurements that astronomers might already do on a daily basis.

Then just take the Earth that has suddenly doubled in size. To make it simple, I thought that if you take a cube and double its length, width, height, you have multiplied its mass by a factor of 8. Apply that to the Earth; increase the mass of earth by a factor of 8 based on it doubling in size. Then by what factor has the Earth’s gravity been increased by? Even if we as humans have doubled in size yet not visually noticed, would we notice the significant increase in gravity upon ourselves? How much more energy would be required for a rocket to reach escape velocity due to increased gravity? Would we notice that? As I say, if I’ve over thought it, then it might be because I’ve misinterpreted this Thought Experiment. At what point is a thought experiment scheduled to stop?

I could go on, just from my own thoughts. The surface of the earth rotates at a given speed. Double the radius of Earth and the surface of the Earth is moving faster, even for the same one rotation per day. I thought combine that with the sea water volume that would have also increased. I thought there will be significantly more Heat Energy in the sea for any given sea temperature. Heat and temperature being two different things. The speed of the surface of the earth and sea temperatures playing a major part in driving the Earth weather. Would we notice the difference in the Earths weather? I can go on further with other things we would notice, but I’m even beginning to boar myself. So is the original question posed just as a simple analogy (or some different appropriate word), or is it a thought experiment, which in my mind at least doesn’t necessary have an ending until the thought experiment is exhausted?

I don't know if doubling the size of the Sun would be good for us on earth. Would that mean more heat? More rays reaching the earth? More global warming? Everything we have now on earth has been tested by time. Humanity has been able to survive on earth all these years because we've had a good relationship with the sun and moon. Change that, and you change the outcome for humanity. That's my guess.

 

[Magna-Carta]

If all the planets doubled in size and their distances shrunk accordingly, then there would be an obvious difference.

Of cause.

If the distances remain the same, and the planets double, you wouldn't be able to tell.

Let’s say that if the distance between the Earth and Moon remained the same, and then the size of the moon was doubled. Then the moon would look bigger as viewed from the earth. (even when the size of the earth is doubled) Because you have made the moon physically bigger. You would therefore notice that something had changed, unless you then also increase the distance to make the moon look visually smaller, by moving the moon further away.

UPDATE:
It’s easily to see. Take two balls and place them say 10ft apart. Stand by one ball and look at the other. Then get someone to replace the ball you are looking at with one double its size. It will look bigger, regardless of the size of you or the size of the ball you are standing next to. That larger ball you are looking towards will only look the same size as previous, when viewed from where you remain standing, by doubling the distance between the two. Apply that to the earth and moon

 

[oldlongwalker]

Of cause.


Let’s say that if the distance between the Earth and Moon remained the same, and then the size of the moon was doubled. Then the moon would look bigger as viewed from the earth. (even when the size of the earth is doubled) Because you have made the moon physically bigger. You would therefore notice that something had changed, unless you then also increase the distance to make the moon look visually smaller, by moving the moon further away.

UPDATE:
It’s easily to see. Take two balls and place them say 10ft apart. Stand by one ball and look at the other. Then get someone to replace the ball you are looking at with one double its size. It will look bigger, regardless of the size of you or the size of the ball you are standing next to. That larger ball you are looking towards will only look the same size as the other, when viewed from where you remain standing, by doubling the distance between the two. Apply that to the earth and moon

I meant the absolute distance. The distance between the sun and the earth is about 93 million miles. That relative distance between them would still be the same if everything doubled in size. Does that make sense?

 

[Medusa]

I don't know if doubling the size of the Sun would be good for us on earth. Would that mean more heat? More rays reaching the earth? More global warming? Everything we have now on earth has been tested by time. Humanity has been able to survive on earth all these years because we've had a good relationship with the sun and moon. Change that, and you change the outcome for humanity. That's my guess.

But, if everything doubled, wouldn't the relationships between them remain constant? Isn't that the spirit of the question?

 

[Magna-Carta]

I meant the absolute distance. The distance between the sun and the earth is about 93 million miles. That relative distance between them would still be the same if everything doubled in size. Does that make sense?

Of cause that makes sense, but if you are viewing the Sun from Earth and you double the size of both, maintaining 93 million miles between the two, the sun will look bigger when viewing the sun from earth, because you have physically made the sun bigger. Nothing is going to look the same size when you have made them bigger.

Apply that then to your question: "Suppose you wake up tomorrow and everything in the universe has doubled in size. Would you be able to tell the difference?" Yes because eveything has double in size so you would notice a change, because everthing looks bigger than previous.

UPDATE:
Look at it in a different way. If you were standing in an empty room, regardless of your position, and there were several spheres in the room. Then the next day someone replaced them with spheres that were double in size in the same position as the previous ones, would they look smaller, larger, or the same size to you? Would you notice a difference, due to doubling of size?

 

[Medusa]

I thought that if the doubling of space/distance wasn't a thing to be included, then it would have been very obvious to me that something had changed. Because objects, planets, stars, moons would/will look bigger if there distance away wasn't doubled as their size was doubled.

@oldlongwalker said “Suppose you wake up tomorrow and everything in the universe has doubled in size”, so for me I included everything. Including thinking about wavelengths of light. (Light wavelengths being something I’ve already mentioned somewhere here) I thought that if the wavelengths of light were also doubled, then we would then see colour differently.

I also considered doubling the speed of light, as in doubling everything. But for me at least I then saw that as being a constant, so I ruled it out. In that I believe (personal opinion) that the speed of light in itself isn’t a speed limit. But perhaps there is something about the universe itself that is or has the speed limit of 186,282.397 miles a second within it (a number that I’ve posted previously in a different thread as being my favourite number.) In that nothing can travel faster than 186,282.397 miles a second, ‘including’ light. Hence the reason why I said the visual timing of the sunset would be differnt to.

UPDATE:
Would tides be different too -- something noticeable? Due to the increased doubling of size of the moon, due to its then 8 fold increase of the moon mass.

Another thing I wondered about was the doubling of size of atoms, and therefore its atomic weight. Would that cause different kinds of chemical reaction? I personally don’t know, it was just a thought.

With the speed of light and color perception thing, wouldn't our color receptors, rods and cones, having also doubled, negate any change in perception?

 

[Medusa]

Of cause that makes sense, but if you are viewing the Sun from Earth and you double the size of both, maintaining 93 million miles between the two, the sun will look bigger when viewing the sun from earth, because you have physically made the sun bigger. Nothing is going to look the same size when you have made them bigger.

But you won't perceive them as bigger because you and every aspect of you is also bigger.

 

[Magna-Carta]

But you won't perceive them as bigger because you and every aspect of you is also bigger.

The diameter of the moon is approx. 2,100 miles. Let’s for argument sake say that you are 1.5ft wide. If you then look at the moon and double both the size of you and the moon. The moon is now 4,200 miles in diameter, and you are 3ft wide. Is the moon to you going to look the same size, smaller or larger?

EDIT:
Let’s look at it a slightly different way. Let’s say you are a very young small child, and then you grow up to be 3 or 4 times the size of your previous child self. Is the moon to you then going to look same size, smaller or larger? If you have increased 3 or 4 times in size, does the moon also have to increase 3 or 4 times its size to look the same to you as when you were a much smaller child?

 

[Medusa]

The diameter of the moon is approx. 2,100 miles. Let’s for argument sake say that you are 1.5ft wide. If you then look at the moon and double both the size of you and the moon. The moon is now 4,200 miles in diameter, and you are 3ft wide. Is the moon to you going to look the same size, smaller or larger?

The same size. The difference between 2100/1.5 and 4200/3 creates the same relationship.

 

[Magna-Carta]

The same size. The difference between 2100/1.5 and 4200/3 creates the same relationship.

Let’s look at it a slightly different way. Let’s say you are a very young small child, and then you grow up to be 3 or 4 times the size of your previous child self. Is the moon to you then going to look same size, smaller or larger? If you have increased 3 or 4 times in size, does the moon also have to increase 3 or 4 times its size to look the same to you as when you were a much smaller child?

As you were growing up and getting bigger, did you get the sense the that the moon was geting significantly smaller becasue you were getting bigger. As you were getting bigger, say by a factor of 3, do you also feel that the moon would also have to increase by the same factor to look the same size to you as when you were a child.

 

[Medusa]

Let’s look at it a slightly different way. Let’s say you are a very young small child, and then you grow up to be 3 or 4 times the size of your previous child self. Is the moon to you then going to look same size, smaller or larger? If you have increased 3 or 4 times in size, does the moon also have to increase 3 or 4 times its size to look the same to you as when you were a much smaller child?

As you were growing up and getting bigger, did you get the sense the that the moon was geting significantly smaller becasue you were getting bigger. As you were getting bigger, say by a factor of 3, do you also feel that the moon would also have to increase by the same factor to look the same size to you as when you were a child.

Do you ever get the feeling you're making something harder than it has to be?

 

[Magna-Carta]

Do you ever get the feeling you're making something harder than it has to be?

I'll ask myself this question. "If for argument sake am 2ft tall, and the moon is 2100 miles wide. Would the moon have be 6300 miles wide to look the same to me if I became 6ft tall?"

My answer would be no. The ratio of me & the moon doesn’t have to remain the same as I get bigger (taller/wider) for me to perceive the moon as being the same size.

Going back to the original question, “Suppose you wake up tomorrow and everything in the universe has doubled in size. Would you be able to tell the difference?” Yes, I would be able to see the difference, regardless of whether I doubled in size from my current 6ft to 12ft.

UPDATE:
The moon takes up the same space in the sky regardless of my own size in relationship to it. So if the size of the moon was then doubled, it would take up a much larger space in the sky regardless of my own size in relationship to it. The moon would therefore look bigger to me when doubled in size, simply because it’s taking up a larger space in the sky, as I view it from earth. I would therefore notice a difference if everything in the universe doubled in size, including me. Regardless of how many pies I’ve eaten. The moon would be covering a larger space in the sky. It's occupying more space in the field of view when its doubled in size.

 

[rbtvgo]

This is a sweet notion and I would love for it to be true, but it simply isn't, at least not consistently.

Lots and lots of people put in the work and do not achieve the reality they want. That's just hard cold life. Better to find a balance between putting in the work and finding contentment in where you are, with what you have.

Hard work does not guarantee success. I will add this...............hard work will reveal your strength and your weakness and it may be that what you desire is not what you really need. It's crazy unless you can accept the fact that someone is looking out for you. Who? I mentioned it before. Go back and look. Life............. your life, my life go down different streets. Mine is where it needs to be. Yours is where you want to take it. There is no balance to achieve. Reach out an try.................otherwise you can play it safe and moan about how unfair life is.
I really don,t want to say this but I will. God has you, reach out to him, per-sue your desires and let him direct you. Accept what he says and keep moving forward.
Close your eyes, ask the Lord for direction and then...................just listen!
bob

 

[oldlongwalker]

I'll ask myself this question. "If for argument sake am 2ft tall, and the moon is 2100 miles wide. Would the moon have be 6300 miles wide to look the same to me if I became 6ft tall?"

My answer would be no. The ratio of me & the moon doesn’t have to remain the same as I get bigger (taller/wider) for me to perceive the moon as being the same size.

Going back to the original question, “Suppose you wake up tomorrow and everything in the universe has doubled in size. Would you be able to tell the difference?” Yes, I would be able to see the difference, regardless of whether I doubled in size from my current 6ft to 12ft.

UPDATE:
The moon takes up the same space in the sky regardless of my own size in relationship to it. So if the size of the moon was then doubled, it would take up a much larger space in the sky regardless of my own size in relationship to it. The moon would therefore look bigger to me when doubled in size, simply because it’s taking up a larger space in the sky, as I view it from earth. I would therefore notice a difference if everything in the universe doubled in size, including me. Regardless of how many pies I’ve eaten.

Try making it simpler. Imagine yourself in a box 20x20x20. You are 5 feet tall. There is a ball in the box 1 foot in diameter. Both you and the ball are each 1 foot away from each opposite wall. You go to sleep. When you wake up, unbeknownst to you, everything in the room has doubled in size. Since everything has doubled, all the proportions between you, the walls and the ball will be the same, just larger than they were. The room is 40x40x40, you are 10 feet tall, the ball is 2 feet in diameter and you are both 2 feet away from opposite wall. Your height is still 1/4 the height of the room. The diameter of the ball is still 1/20th the height and you are both 1/20th of a distance from the nearest wall.