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Physics, Astronomy & Cosmology / Re: What happens inside a black hole, and how do black holes evaporate?

« on: 22/09/2020 14:32:04 »

Inside the event horizon, what does it mean to say space and time change their roles? How does that happen? What are its implications?

It means one spatial dimension (the radial one, ‘up/down’) becomes time-like, and the time dimension becomes space-like. It is all very much like it is on Earth here, and thus somebody falling into a very large black hole would not notice the crossing of the event horizon. Local physics works the same. He cannot send a signal ‘outward’ because that is no longer a spatial dimension. It is the past, and one cannot send a message into the past, but one can receive a message from the past.

Would every direction inside event horizon look like it is pointing towards the singularity?

All directions are always spatial directions, and thus do not point towards the singularity, just like you cannot point towards or away from the location of the big bang, which is not a location in space, but rather a point in the past, and the opposite direction pointing to the future. It isn’t a direction you can point to with your finger.  The black hole singularity is in the (finite) future of our observer within.

How would time pass?

Quite normally. As I said, our observer falling in has no direct reason to notice an immediate change. The model of time as a thing that ‘passes’ isn’t really compatible with a model of spacetime being discussed. Spacetime says space and time is one 4-dimensional thing, not time that passes and space that doesn’t (different things).

What is space inside event horizon?

Normal 3D space. As I said, you’d not immediately know the difference. Space becomes more curved as the singularity approaches, and you’d notice that, even before the event horizon is crossed if it is a smaller black hole. Doing a hyperbolic pass near a neutron star will kill you even though you don’t touch anything.

Would singularity be everywhere inside event horizon? Or is it just an illusion and there is only one singularity at the center?

It’s not an illusion and its not ‘everywhere’.  It is a time more than a place, but it has a shape that is typically a ring. Only a Schwarzschild black hole has a point singularity, an idealization unlikely to exist in reality.

Is there infinite density and infinite curving of space and dilating of time inside event horizon?

No.  As I said, you’d not notice crossing the event horizon, so time and space would appear no different than just on the outside to you.

Would there be infinite spaghettification?

There eventually would be spaghettification, yes, possibly outside the EH. Not sure of the difference between regular and ‘infinite’ spaghettification. At some point yes, even subatomic matter will be both compressed and pulled apart beyond the ability of even the nuclear strong force to resist.

Even if a futuristic ideally durable vehicle could somehow bend space and travel faster than speed of light, could it still not escape from inside the event horizon?

You’re talking about a time travel device. If you propose one, then you are already discarding all of the physics used to answer the questions above, so I imagine you can make up your own answers. This is how Hollywood does it.

If such an ideally durable vehicle could survive inside event horizon, could they survive just about everywhere even absolute zero temperature and negative temperatures?

A vehicle doesn’t need to be particularly durable to pass through the horizon. You in a space suit (or you sitting on Earth for that matter) would work just fine.

What are other methods of escaping from inside event horizon? Like one half of a virtual particle pair appearing inside event horizon and other half outside

That is new material, which reduces the mass of the black hole by adding a negative mass virtual particle to it. I’m not really sure if adding negative things to something counts as the thing escaping, but its mass goes down, so there’s that.

if a hypothetical vehicle could generate enough virtual pairs(like exciting the vacuum somehow) from inside the event horizon, then would some of those particles the vehicle generated appear outside event horizon due to HUP?

No.  A device cannot be made that generates a virtual particle pair well into its past. That again would be time travel, or at least sending messages to the past.

Would the boltzmann brain scenario work and the atoms and molecules outside blackhole arranged themselves into an exact replica of hypothetical vehicle?

First of all, Hawking radiation is pretty much confined to light and other massless radiation. I cannot build a vehicle out of photons and gravitons and such. Yes, by sheer improbability, a vehicle can appear at a random point in space, complete with you in it, with memory of having fallen into the black hole. That works without the aid of a more original vehicle actually being inside the black hole or not. Is it the same vehicle?

How to calculate probability of something like that happening? Eg. swampman scenario?

Yes, exactly, except there is no need for the original to be destroyed by lightning or whatever means. You are in jail, but a swampman event creates an identical copy of you on the outside, complete with memory of being in jail. Have you escaped or is it a different person? Does it really matter to the one on the outside if the one still in jail is improbably destroyed beyond ability to identify?

2. Is there any way to speed up the black hole evaporation process(eg. from 1e+60 years to a few years or even seconds) by increasing the number of negative side of materializing particle pairs exponentially?

There is no known way to generate negative mass. It would have to be non-virtual and somehow transported to the black hole and dropped in. Doing so isn’t going to extract any of the contents out of the black hole any more than does Hawking radiation.

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Physics, Astronomy & Cosmology / Re: If everyone in the world went swimming at the same time, would sea level rise?

« on: 05/09/2020 04:28:45 »

Very good point about the amount of available coastline!

But wouldn't the rate at which people were getting into the water be slower than the rate of water redistribution?

Also, presumably bringing all that mass close to the seashore would depress the land there a bit, so sea level would apparently rise (by a picometre or so?), and all the gravity associated with those people would pull up the water more, making a further apparent rise, surely?

OK, let's iron out a few variables.  Suppose the weather is nonexistent and the water is mirror calm all over the Earth.  All the people are already at the shore but waiting, so their gravity isn't going to change much by a small amount of motion. We remove the moon so tides go away. Can't measure a micron of sea level if it's boinging up and down with the tides.

That said, we have two scenarios: Do it quick or do it slow and wait for a new equilibrium to form.

Quick method:  A relatively small group of people jump into a tight bay and the water level rises there in accordance with the new volume displaced. That might be even a centimeter.  The water eventually runs out of the bay, but this is the quick and dirty method here. We're not measuring the sea level with a stick in the middle of the ocean (which is unaffected for hours by this), but just a local measurement. What people are doing elsewhere in the world is immaterial for the quick method. You get a temporary local sea level rise due to the local group going in.  The change causes a tsunami of sorts that takes time to get to places not near shorelines.  Point is, with the quick method, it's the local group that matters, not the whole population of Earth getting in the water.  It seems not in the spirit of the OP, so we instead go to:

Slow and permanent method:  The entire population gets in the water and stays there until a new equilibrium forms, which might take days (or much more!).  The sea level rises in accordance with a calculation similar to what BC did in the initial reply.

The surprising part of the answer for this is that it doesn't matter what water you get into.  I have a small waterfall in my back yard with a pond that could hold probably a dozen people submerged.  Suppose 12 people do that instead of wading into the ocean.  Sea level rises just as much (after some time) due to that. They don't have to be in the ocean at all. The people displace their weight in water which exits the pond that much sooner and adds their mass to the ocean after a day (in my case).  My brother can do the same thing where he lives and it would take decades for the sea level to rise from his action, but it would eventually. He lives near water that runs into Lake Superior, a lake that drains so slowly that any change to its level might linger for literally decades.  But sea level would rise eventually due to my brother sitting in a nearby pond.

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Physics, Astronomy & Cosmology / Re: Speed of light from different observers?

« on: 04/09/2020 13:21:08 »

Difference, actually.

No.
Delta f/f is a ratio and that's what's proportional to the speed.

If I tell you that the beat frequency is 1000Hz you can not use that to determine the speed.

It does addition/subtraction of the two signals to get the beat frequency. If the BF is 1000Hz, I can very much use that to determine the speed since the signal was sent at a known frequency, so the ratio can then be computed.
Key word is that known frequency that the device sends out.  When measuring a random beam of light, the frequency is not known since it is what we're supposed to be measuring.

So, you need both the difference and the base frequency.

Which is why a radar gun works, because it has both, and why such a device cannot measure frequency of a light beam because it doesn't have either.

But point taken.  I can put a laser on a train, which puts out a known frequency. I have a similar laser on the platform putting out the exact same frequency.  I can use radar-gun technology to subtract the two signals to get a beat frequency which can thus tell me the frequency of the signal coming from the train. That's pretty much a direct measurement of frequency.  The we take that same light and measure its wavelength, and poof: we have a measurement of light speed utilizing a beam of light whose exact wavelength is not known ahead of time, but is close to one that is.

Side note: The radar gun does not take relativity into account. It wouldn't give accurate readings for cars moving very fast. They don't need to since their use-case is always very low-speed difference between the gun and the target and background.

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Physics, Astronomy & Cosmology / Re: If everyone in the world went swimming at the same time, would sea level rise?

« on: 04/09/2020 12:55:25 »

A good thorough answer from B-C, despite the one error Evan points out.

I'd like to mention what it would take for all of humanity to get into the ocean "at the same time". What is the length of the combined shoreline available to humans?  Some of the places it would take some time to get from the beach to a swimming depth.
A rough estimate of the shoreline is something like half a million km which yields a wall of people around 10 deep. So that's not unreasonable.  It takes less time for 10 people to enter the water than it does for any one of them to get to a swimming depth, at least in some places.  In other places, people 10-deep are jumping off cliffs like lemmings. Jumping off a boat doesn't count since anyone in a boat is already contributing to the sea level.

Also, the sea level will rise at the shores far more than those 2.5 micrometers since all the new volume is there and it would take time for that displaced water to reach the places in the ocean where people are not doing this.

Water evaporates from the ocean at a rate of about 16 billion kg per second if my sources are correct. All of humanity masses maybe 30 times that, so if they all manage to get their 10-deep line into deep water in under half a minute, they might actually out-pace the rate at which the ocean empties itself.

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Physics, Astronomy & Cosmology / Re: Does spacetime bend only locally around objects?

« on: 22/08/2020 12:09:51 »

1. Do we at all times emit black body radiation? Do some of that undetectable light escape the earth and travel indefinitely to outer space as photons?

We emit radiation at all times, yes. We also reflect much of ambient light, so it isn't really blackbody radiation.

2. In the athlete kicking the ball example, is there no change in gravitational field of earth even a tiny bit? If the change did happen, it has the potential to be detected after 1 year by a detector 1 light year away?

Again, yes, it changes the field, and that change must propagate at c, so in theory, it is detectable.

3. Is there some way we affect the whole universe by doing our daily activities?

Only part within our future light cone, which hardly covers the whole universe.

Like increasing entropy macroscopically?

Do we do that?  It's not like the entropy wouldn't have happened without our presence, so all we do is rearrange the timing of it a little.

The goal is to show we have a sort of universal range and we change the universe slightly.

If Earth was viewed from afar, it would stand out like a beacon in certain light frequencies that don't occur so much naturally. But Earth would effect the universe anyway without needing to be different in some way, so the answer is yes: It is pretty much impossible not to have effects on parts of the universe in our future light cone.

Could a change be made instantaneously across large distances?

Relativity says there is no 'instantly'.  There is not a specific distant event that is simultaneous with a given event here. Quantum mechanics has local interpretations that say no event can cause an effect at a different event separated from the first in a space-like manner. There are also non-local interpretations (like Bohmian mechanics) that require faster-than-light effects. So such interpretations need to deal with relativity of simultaneity. In the end, it cannot, which means that non-local interpretations also need to allow effect to precede cause: A choice made today has effects arbitrarily far in the past.

Like we are made up of a large number of particles, is there any chance some of them regularly exchange information via entanglement with particles billions of light years away?

No. Information cannot be exchanged via entanglement. Cause and effect maybe, but not information. Nobody has ever sent a FTL message.

4. In a universe accelerating in expansion and space between galaxies getting larger, are gravitational waves and photons affected by expanding space? Could they travel slightly faster than light in between galaxies where space is expanding?

The proper distance between us and some distant thing (photon, rock, whatever) is increasing at a rate proportional to its distance from us. For light, that means any light receding from us is increasing its distance from us at a pace greater than c, and beyond a sufficiently large distance, the light coming straight at us is not getting any closer over time.  It might still eventually get here.
No light we see today has ever been as far away from here as 6 billion LY.  Any light more distant than that simply hasn't had time to get here yet.  If it was emitted recently, then it hasn't had time to cross that distance. If it was emitted much further back (say 13.4 billion years ago, the oldest non-CMB light we've found so far), then it was actually emitted quite close by (about 2.8 GLY) but it has had to fight to catch up to Earth moving at 3x light speed relative to the object that emitted it.  That means that in a way, the visible universe is under 6GLY in radius. That's not how they usually express the size of the visible universe.

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Physics, Astronomy & Cosmology / Re: Does spacetime bend only locally around objects?

« on: 20/08/2020 15:32:55 »

Does a body with mass curve space and dilate time only locally, eg 5 km?

'Locally' means 'here', and spacetime is locally Minkowskian (flat) anywhere where there isn't a physical singularity.  So quite the opposite: A body with mass does not exist locally (Earth is not all right 'here'), and does not curve spacetime locally, but it does exist and curve spacetime on larger scales. As Colin points out, there is no limited range to this.

To illustrate: I can draw a chalk triangle in a sidewalk square and the angles will add up to 180° since spacetime is flat locally.  But the larger the triangle I draw, the more the angles add up to something else.

Does changing the mass of a body or moving an object hence increasing its kinetic energy has a very small negligible effect on the entire universe or only the space surrounding that object?

Mass is conserved, so you can't just change the mass of an object. You can only merge it with some other mass that is already there, and spacetime is already curved because of that other mass.  So the merging doesn't really change much.  Rearrangement of mass (such as Earth orbiting the sun) does affect the gravitational field, and those changes (not the gravity, just the changes) propagate through the universe at light speed via gravitational waves.

How can a sensitive theoretical device measure such a small gravitational disturbance from light years away from that object?

Look up the wiki site on LIGO which does just that.

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Physics, Astronomy & Cosmology / Re: Do All Planets (inc Exo Planets) Orbit Their Star In The Same Plane As Ours ?

« on: 02/08/2020 17:56:51 »

Effectively, the orbital plane of a given star system is random. They don't align with the galactic axis in general. Ours certainly doesn't as Kryptid points out.
In a single star system, all the planets that formed as part of that star system (not captured for instance) tend to orbit with a relatively common axis. Pluto didn't form in the same way as planets do, and is in fact a sort of displaced Oort object.

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Physics, Astronomy & Cosmology / Re: If I Was Able To Stop Time, What Would The Temperature Be ?

« on: 30/07/2020 16:25:49 »

Say ewe had the ability to pause time , but ewe would be safe in your own bubble time thing to have fun and play.'

What would the temperature be ? The same as it was before you stopped time ?

I don't think time is something that 'goes', so pausing it isn't going to change the temperature. It would be whatever the thermometer says, which at a given moment in time is a fixed thing.

OK, in a strange set of physics where everything not in bubble-containing-you stops all motion, then as Alan says, temperature outside your bubble is meaningless despite the reading of the thermometer. I can find a picture of a thermometer in a book, and that is essentially 'stopped time'.  What it reads has nothing to do with the actual temperature of the book. If I'm physically in that world instead of looking at it from an outside PoV, then I could not move my 'bubble' because I'd have to push past all this stationary air which cannot move, lacking any time in which to do so. I could not see outside my bubble because no light could move from the outside. So the bubble would just confine me into a small spherical universe, and asking the temperature out there is no different than asking about the temperature of a right triangle in a Euclidean plane.

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Physics, Astronomy & Cosmology / Re: What Happens To Photons After You See Them ?

« on: 29/07/2020 13:40:13 »

Sorry to tell you, but everytime you look at the stars you are killing photons 

Which is why more humane sheep reflect those photons rather than kill them.

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Physics, Astronomy & Cosmology / Re: What Would Happen To A Thrown Ball On A Train Travelling 10mph Less Than 'C' ?

« on: 28/07/2020 19:31:24 »

So, as it passes, you notice a boy throwing a ball the same direction as the travelling train and he throws the ball at 20mph !!  VOILA !!...the ball is now travelling 10mph faster than the speed of light !!

If he throws it at 20mph, then it is moving at 20mph, almost stopped.
If he throws it 20mph relative to the train, then you have to use Einstein's light velocity addition formula: https://en.wikipedia.org/wiki/Velocity-addition_formula#Special_relativity

So the ball is essentially still going 10mph less than c relative to the guy on the platform, with negligible additional velocity.

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Physics, Astronomy & Cosmology / Re: How Did Time Come Into Existence ?

« on: 26/07/2020 01:29:55 »

This is a philosophical topic

Can’t agree with that.  Philosophy might attempt to explain why we are here.  (good luck with that). 

Philosophy covers much more than just that one topic.

In fact, if time cannot be created, it becomes a necessity, if one wants to question our origin.

Our origin isn't the problem.  Cloud cools. Planet condenses out of that. Life forms. Poof: our origin explained. OK, those are processes, so I agree that time is necessary for that, but I wasn't discussing the necessity of time to explain the our origin. We're temporal things, so time is necessarily in the recipe.
I was discussing the application of the verb 'create' as it relates to time. Time cannot be created per my stance. It isn't an object or other contained thing like anything that can said to be created.

So, something, including time (?) must always have “existed”, and is, therefore, eternal.

'Always existed' means essentially existing 'at all times', so yes, I agree that time exists at all times. That's kind of a tautology. It doesn't imply that time is unbounded at either end. There are known cases for instance where time stops, such as at the center of a black hole. It is bounded at the other end at the big bang iff you consider that event to be the beginning of 'time as we know it'. There may be something on the other side, but it isn't necessarily ordered, measured in seconds, meters, light speed, or any of the properties unique to our spacetime.

Technically, even that time didn't start until after the inflation epoch. I always wondered about what it meant for space to expand 2x each tiny fraction of a second. How is a second meaningful at that stage? There's no light, matter, or any regular process by which time can be meaningful. But maybe that's just me being ignorant.

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Physics, Astronomy & Cosmology / Re: How Did Time Come Into Existence ?

« on: 24/07/2020 18:56:26 »

This is a philosophical topic and probably belongs in Just-Chat rather than physics.

When the big bang happened last Tuesday 'Time' would have had to exist first yes for the events to occur agreed ?

If the big bang did not occur at the beginning of time, then sure. As far as I know, it isn't wrong to discuss time on the other side of the big bang event, although since it is not necessarily ordered there, the word 'before' or the tense 'would have had to' may not be applicable.

So. what was the mechanism that enabled time to exist if time did not exist in the first place.

If there is time on the other side of the big bang event, then it exists there, and the big bang is just an event in time.  The big bang then would not in any way be the beginning or creation of time, just the creation of our particular bubble of stuff.

I imagine there had to be something that caused Time to happen

That wording, and the title of this topic, make no sense.  For time to have been created, to come into existence, there would have to be a time when there wasn't time, which is self-contradictory. By the same argument, not even God can create time since by definition there could not be a time before he did that.

If the universe is contained within time, then the universe can be a created thing (an object among others). No viable model of physics models the universe as an object contained within time. That idea fell apart with Newton's vision over a century ago. Religions posit such a thing.

But if time is part of that universe, then the universe cannot be a created thing since there is no part of the universe before the universe. All the consensus theories have time having equal ontological footing with space, which is why it's called spacetime and not space and time.

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Physiology & Medicine / Re: What Is The Sound Of Thought ?

« on: 23/07/2020 16:52:30 »

It is a voice of your choosing, and seems never to be my own voice in my case, but I cannot speak for others.
It can have an accent. There are days when all my thoughts come through in some heavily accented voice like Craig Ferguson or maybe pre-makover my-fair-lady Hepburn.

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Physics, Astronomy & Cosmology / Re: Why is ‘NOW’ Not The Same Everywhere ?

« on: 23/07/2020 14:42:55 »

Well if there's a now here, there must be a now everywhere else as well.  Either that or Earth is something special in that respect.  Personally I get around the issue by not assuming there is a now here.

The problem is similar to asking why I am always 'here' and never somewhere else.  No matter where I go, I never manage not to be somewhere that isn't 'here'.  Either I'm special in that way, or there is no objective 'here', and the latter option seems more reasonable, don't ewe think?

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Physics, Astronomy & Cosmology / Re: Expansion of the universe - what is being measured?

« on: 17/07/2020 11:37:47 »

I was just reading about the Atacama Cosmology Telescope in Chile. Research is as active as ever in trying to determine the age of the universe and the rate at which the universe is expanding. Does this research measure the rate at which matter is travelling through the universe or measure the actual expansion of the fabric of the universe?

The research is intended to determine the actual expansion rates of the 'fabric' of the universe, but since that cannot be measured directly, they instead measure the rate of increase of proper distance between us and distant galaxies over time.  These distant galaxies are generally not travelling very fast through the universe (usually less than 0.02c) relative to said fabric, and thus make a good way to indirectly measure the expansion rate.

The rate has not been constant over time, so for instance some distant galaxy might be receding today at twice light speed, but 6 billion years ago it might have been receding at 1.9c and 13 billion years ago it might have been receding at 3c.  Expansion had been slowing considerably since the early times, and measuring those rates from all the points along that curve is critical to estimating the age of the universe.  Problem is, for any one galaxy, one can only see it at one moment in time, depending on how far away it was then.

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Physics, Astronomy & Cosmology / Re: An expanding flat universe?

« on: 14/06/2020 20:55:50 »

The trumpet shape has been around for a while.  Eg.  https://www.independent.co.uk/news/science/the-universe-is-not-round-say-scientists-it-is-shaped-like-a-trumpet-560046.html. 

I have always assumed it was a “mathematical” model, intended as an aid to understand; rather than something that was meant to be taken too literally. 
No one will be surprised that I have grave reservations about the physical demonstration of:-
 
“The thin end would be infinitely long - but so narrow that it would have a finite volume.”

OK, Mr Arthur gets a good prize for bad reporting of science.  No scientist claims the universe is shaped like a trumpet, an object with edges.  The bit about finite volume comes probably from Gabriel's horn ( https://en.wikipedia.org/wiki/Gabriel%27s_Horn#:~:text=Gabriel's%20horn%20(also%20called%20Torricelli's,surface%20area%20but%20finite%20volume.&text=The%20properties%20of%20this%20figure,Torricelli%20in%20the%2017th%20century. ) a 3D shape which has zero to do with the shape of the universe (a 4D thing).

What the scientist are doing is taking a circle of space and plotting just that circle as it expands over time.  The circle can be any size, and nobody suggests that the universe is bounded at that circle, so the actual shape is something 3D (not a 2D circle) without bounds, expanding in a non-linear curve over the 4th dimension, time.  The 'trumpet' shape is just what you get if you graph the expansion rate (the scalefactor to name it more correctly) and twirl that graph on its time axis.  It is the shape of expansion at best, not the shape of the universe at all.

Oh, and this news is decades old.  I knew this expansion curve 30 years ago, even though it definitely has been tweaked since then. I think it was merely published as a way to get hits to their hostile site, which I found impossible to read without ad-blocker on.

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Physics, Astronomy & Cosmology / Re: An expanding flat universe?

« on: 12/06/2020 14:27:00 »

I get the Euclidean non Euclidean thing after reading up on it. The universe is flat and I'm seeing the parallel lines. The universe is expanding in all directions and I'm seeing those parallel lines expanding into a trumpet shape. So where am I going wrong?

The trumpet shape is probably due to something graphing space vs time.  Flat space should depict parallel lines in a graph of x vs y (both space), not x vs t.  If you expand that graph, the lines remain parallel.

The surface of Earth is a nice example of non-Euclidean 2D space.  It is difficult to draw it on a flat paper map, and any attempt to do so ends up distorting continents and such.  Parallel lines drawn on the ground always meet.  Triangles have their angles add up to more than 180°.  That's a great way to show that the surface of Earth is not flat.
They've actually attempted to do the triangle thing to measure curvature of space.  It does actually curve locally due to gravity, but on a large scale it seems to be flat.

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Physics, Astronomy & Cosmology / Re: An expanding flat universe?

« on: 11/06/2020 20:28:55 »

Can anyone help me visualise a flat universe that is expanding in every direction? It would seem to me that anything that is flat could not retain its flat shape if it were expanding in every direction.

Don't understand your inability to visualize it.
Consider any shape, like a heart of size 1.  Now double every dimension in it, so it is twice as wide, tall, and thick, but size 2 now.  It is the exact same shape, just expanded.  Ditto for the flat universe.  If it was flat before, doubling its space in all dimensions does not affect the shape at all, so it's still flat.  Expansion does not inherently change the shape of something.

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Physics, Astronomy & Cosmology / Re: Is this gyroscopic antigravity?

« on: 01/06/2020 06:16:37 »

Wiki page on Eric Braithwaite says:
"In his lecture before the Royal Institution he claimed that gyroscopes weigh less when spinning and, to demonstrate this, he showed that he could lift a spinning gyroscope mounted on the end of a rod easily with one hand but could not do so when the gyroscope was not spinning."
"In his 1974 lectures, Laithwaite suggested that Newton's laws of motion could not account for the behaviour of gyroscopes and Laithwaite suggested that they could be used as a means of reactionless propulsion."

The effect is easily demonstrated.  The spinning gyroscope (a wheel at the end of a long axle, lifted by the other end) has only weight, but if not spinning, torque must also be overcome, making it far more difficult to lift despite no difference in weight.  I doubt that a professor has that poor of an understanding of simple gyroscopic effects, so my impression is more of somebody claiming amazing feats to the gullible when it is just ordinary (Newtonian) physics going on.
I think I can find a link to a video of somebody doing this, discussed in another thread.

Not sure if this has anything to do with the OP.  On the ISS, the device would have no weight in the first place and would not precess, and has no concept of being 'lifted'. I don't see any mention of 'jumping' in any descriptions in the searches I ran.

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Physics, Astronomy & Cosmology / Re: Can new telescope show there was something before the BBang?

« on: 16/05/2020 11:24:24 »

But still, I find it difficult to take in talk of 20 billion LY away when the BB was 13-14 bly ago - can't get rid of the thought that suggests there was/is something beyond the Bbang 'out there'.
And how are these distances calculated?

The calculation is pretty simple.  Take GN-z11, which has been seen before this James Webb telecope comes online.
It is 'currently' 32 BLY away, meaning the proper distance between Earth now and that object at a moment when the universe is 13.8 BY old is about 32 BLY, but we're not seeing what it looks like now, we're seeing it massively in the past when it was quite nearby.  It is increasing that distance at 2 1/3 times the speed of light, all due to space expansion, not to either us or it actually having a particularly abnormal speed. So the calculation is to just take that recession speed and multiply it by the age of the universe.
The light we see from GN-z11 was emitted from only about 2.66 BLY away when the universe was under a billion years old, and that light took about 13.4 BY to get here.  Somewhat more distant is the cosmic microwave background which is emitted by material which is currently 45 BLY away, very close to the 46 BLY current radius of the visible universe.  Anything currently beyond that 46 BLY distance could not have ever had a causal effect on us, and is thus in complete superposition from our point of view.

Wiki en.wikipedia.org/wiki/GN-z11 comments on exactly this:

At first glance, the distance of 32 billion light-years (9.8 billion parsecs) might seem impossibly far away in a Universe that is only 13.8 billion (short scale) years old, where a light-year is the distance light travels in a year, and where nothing can travel faster than the speed of light. However, because of the expansion of the universe, the distance of 2.66 billion light-years between GN-z11 and the Milky Way at the time when the light was emitted increased by a factor of (z+1)=12.1 to a distance of 32.2 billion light-years during the 13.4 billion years it has taken the light to reach us.

I personally don't find those figures exactly consistent, but then I'm also assuming a constant rate of expansion, or at least pretty close to it.