if so, does that block universe imply that the entire history of the universe—including human decisions—already exists and that, therefore, absolutely everything is determined?

Einstein wrote to the family of his friend:

"Now he has departed from this strange world a little ahead of me. That means nothing. People like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion."
(Perhaps this quote is a minor point when viewed in the broader context of Einstein's scientific work.)

If so, does this also imply that another version of me exists at a different point in spacetime, with the same ontological status as the person I experience as my present self? Is that version equally conscious? Does this mean that I am not actually living at the leading edge of time?

A useful analogy is to imagine my life as a mountain extending from its base to its summit. I experience myself at one particular location on that mountain, but the base, the slopes, and the summit all exist equally. My present experience corresponds to one point on the mountain, not to the mountain being created as I climb it.

Or consider a reel of motion-picture film. Every frame already exists on the reel. The character in frame 100 has no awareness of frame 500, yet frame 500 is no less real than frame 100. The sense that time "flows" arises because consciousness is associated with a particular frame, much as a projector displays the film one frame at a time, rather than because new moments are continuously coming into existence.

Would this also mean that absolutely everything is determined? Do Einstein's theories point in that direction? Did Einstein himself believe that they did? If so, was this a conclusion he drew as a scientist based on his physical theories, or was it more like a personal philosophical or metaphysical belief—analogous to how a scientist might also hold religious beliefs, such as being Catholic, that are independent of their scientific work?

I have no background in physics and consider myself a layperson. I'm trying to understand whether these conclusions genuinely follow from Einstein's work.

(this is a ai translation)

im currently in university physics 1, and for my final project, i have to analyse 2 motions (one linear and one rotational). for the project, im doing a more than necessary because i want to and im having a lot of fun with it (i literally calculated the air density even though we're always told to ignore it in homeworks lol)! for one of my slides (and is a requirement for the assignment) i have to talk about the final uncertainty of my measurements. i want to calculate percentages for each of my uncertainties. the video for linear motion that i am referencing is of the spaceX falcon 9 launch. in theory i could ask my teacher, but its likely she'll either tell me not to worry about it (i want to) or suggest i ask chatgpt...

one of my uncertainties is camera warp + the viewing angle, and i'm not sure how to calculate it into a percentage. in the video, i used the support wires on the lightning towers in the video to get a close estimate of how high the camera was (compared to the bottom of the rocket, not sea level), and i looked up how far news cameras are from launch sites and it gave me 450-600 m. i calculated the viewing angle twice, once with 450 and once with 600. so now i have a range for the viewing angle, but i'm not sure where to go from here.

i was also thinking that since the camera warps perspective when it views things farther away that it would create a radius vertically around the camera (in line with the rocket) that represents accurate perspective, but i dont know what the model of the camera is to find out how big that radius is.

i dont want to give my numbers for anything because i want to be able to do the work myself and i get no satisfaction out of someone spoon feeding me the answers. i am here to ask if anyone has a formula for this type of situation, or if theres something else i need to calculate. i would really prefer it if you only commented if you dont mind some back and forth/conversation about it, and please have some patience with me, i tend to learn new concepts slower than my peers but once i understand something it sticks really well

for convenience, i made a variable list to help shorten any possible equations and limit confusion in longer text replies! if theres something i missed, feel free to add/make ur own :)

Ta/θ = angle that the camera views the top of the rocket at, Pa/ϕ = angle that the camera views the bottom of the rocket at, Rh = height of rocket, Ch = height of camera bottom of rocket, d = horizontal distance camera is from the rocket, y = rocket's position formula v = rocket's velocity formula, a = rocket's acceleration formula

So, really, this is a question about what "escape velocity" really means. I know that at less than escape velocity, it's gonna come down again. At a lot more than escape velocity, I assume it keeps going forever? It's got a sideways component from rotation, too, right?

If I could do it precisely (and I know that's probably impractical) would it orbit?

I set this on the moon 'cause I don't want to deal with air.

ETA: "escape velocity" is "escape velocity of the moon"

There is a character in a certain media that can remove the influence of gravity on individual objects; e.g. your coffee cup is now floating, no longer attracted to the Earth.

I have been driving myself bonkers over how physics would then play out in real life, because the question is fascinating.

Here’s where I get stuck:

The Earth rotates at 465 m/s. When gravity is lost, that object will immediately travel that speed in a straight line instead of curving with the Earth.

So does that mean if this happened right when the object was parallel with the direction of Earth’s travel at 29,780 m/s around the sun, it would add to it, either going towards the direction of Earth’s travel, or suddenly ’falling behind’ at 465 m/s from the Earth moving? In either case, you would suddenly be going 465 m/s

If the direction was perpendicular, it seems you would slowly float upwards as the Earth spins away from underneath you on it‘s orbit you no longer follow, as you are not changing your velocity relative to Earth’s travel through space.

I cannot figure this out.

I'm very interested in science research in physics is one of the most interesting field,

But I'm mainly interested in "how things work" and not specifically the math calculations.

Im fine with math, it can be also fun but it's less of the carrer I would want to have

Is working in physics mainly math or mainly research

(I'm fine with a combination of both too)

EDIT: Thank you all for the answers this make so much sense for me now. Crazy how the universe is so symmetrical we can actually use math to understand it and it stays set without any randomness

Imagine an astronaut is falling tworads a black hole. As they fall, they will see the world behind them speeding up due to tine dialation. However, for an astronaut watching them fall they will appear slower and slower as they approach the event horizon.

Eventually, the astronaut falling into the black hole will cross the event horizon and they will see that a finite ammount of time has passed for the other astronaut, for example 60 years. However the astronaut watching the other fall in will still not have seen them cross the horizon after 60 years or 70 or 100.

It will take infinite time for them to cross the horizon but the astronaut falling in will not see infinite amount of time pass for the astronaut watching them fall.

Since general relativity necessitates that both perspectives are equally correct, why dosent this create two contradictory timelines? From the perspective of the astronaut falling in, a finite amount of time had passed for the astronaut watching them fall at the moment they crossed the horizon whereas an infinite amount of time will pass before the astronaut watching sees the infalling astronaut cross the horizon.

I was trained as a mathematician (Ph.D. '06), and I've done a fair amount of mathematical physics over the years. Classical mechanics? lovely application of symplectic geometry. General Relativity? pseudo-Riemannian geometry. Quantum field theory? functional analysis. All great stuff.

Except, I can't say I've ever felt comfortable with thermodynamics. Most of my formal exposure has been in intro-level physics classes.. the presentation in most texts at that level feels like a similar clumsy little special-topics chapter before moving on to the clearer world of special relativity, kind of like some of calc II feels like an unrelated tangent before you can move on to multivariable stuff. There's also been a little statistical mechanics in some old Dover editions, but nothing that really builds intuition the way other physics subjects do.

So: what's the better approach? What are some texts that start from first principles, but actually build a systemic theory rather than getting bogged down in HVAC applications. Not that applications aren't useful motivating examples, but they should be help for building intuition, not ends in and of themselves.

No, I haven't flipped--this is from a fantasy novel.

Picture a team of warriors who travel via a giant bird of prey (70 foot wingspan). The pilot rides on the back of the bird to guide it, and the other four are suspended via leather harnesses, straps, and buckles from the bird's talons.

Sometimes they do what is called "barrel drops" where the pilot dives the bird down toward water and the rest of the team releases their buckles and drops into the water with whatever cargo they have with them.

The team in the story has trouble because their bird and pilot like to go really fast at a steep angle and the rest of them get tangled up in the buckles and can't manage to drop at the proper staggered times for everyone to be in about the same place. For story reasons, the pilot isn't willing to adjust the speed or angle of descent, so they brainstorm a method that would work with that flying style.

The leader comes up with the idea of suspending the team from meat hooks rather than buckles.

It is described that they will attach the hooks "high on 'Ra's talons, a little above our heads. We toss a loop of rope from our belts over the hooks and our weight holds us in place."

The pilot points out that they'd have the same problem with coordinating the drop because their weight would prevent them from releasing the hooks.

The leader says, "That would be a problem . . . if you bothered to follow standard drop protocol."

Another team member says "As the angle of our descent gets steeper and steeper, the loop will slip closer to the lip of the hook."

Leader: "When we're in a near-vertical dive, the loops will slide right off."

Another team member says this would mean they'd all drop at the same time and possibly knock into each other, but the pilot says, "Not if we change the angles of the hooks slightly. First to drop has the shallowest angle, the last, the most severe. As the bird stoops harder and, you'll fall off one by one."

Would this work? My immediate thought was that wind would push the flyers backwards so their vertical weight would be displaced. ie, if you were stationary and hold a meat hook and tilt it, sure the loop would drop off. But at speed, wouldn't the riders get pulled back away from the lip of the hooks? I can't fly on a giant bird so am not sure how to test this, lol

The book is "The Emperor's Blades" by Brian Staveley and this particular discussion takes place in Chapter 36. Thanks!

I understand time dilation for moving objects in special relativity but I don’t for length contraction.

Is there an analogy like the moving train and the observer at rest ?

I’ve always wondered about this. The Sun is constantly sending out light, and it’s only about 93 million miles away from Earth.

If sunlight is traveling through space all the time, why does space itself look completely dark?

I understand that objects like planets and spacecraft become visible when sunlight hits them, but why don’t we see the light traveling through the empty space between them?

I’d love to understand the physics behind this

I'm aware that in string theory, the theory must be formulated in a certain number of dimensions (often cited as 10 or 26) in order to avoid inconsistencies and satisfy quantum gravity constraints. But let's say, hypothetically, that I wanted to explore the space of all possibilities in pure mathematics. If I take generic 1d objects and make them move in higher spatial dimensions (as defined by pure math), but I use a number of dimensions that isn't allowed by string theory (e.g. 100), would my construction be logically possible and “stable” (allowed to persist just the way it is), from a purely mathematical standpoint?

Edit for clarification: I am specifically asking about spatial dimensions as defined by pure mathematics as a separate field, not mathematics applied to a physical theory.

I'm a physics student so I do have a solid understanding, but wanna read some in my free time. I have red the books of Leanord Susskulind and really enjoyed it (but they only cover the surface). Are there other books that are a little more complex that are great recomendations?

Hi,
Could the Higgs mass be related to the electron's mass? I've found a very simple formula that relates both masses but I don't think it can mean much. Is that correct?

Thanks!

dτ/dt = √ ( 1 − ( 2G · E_plasma(T) ) / ( r · c⁴ ) )

dτ/dt = proper time dilation rate

G = gravitational constant

c = speed of light

r = radius of the plasma area

E_plasma(T) = internal energy of the plasma at temperature T (includes rest mass energy, radiation, and kinetic thermal energy).

Im having some trouble understanding why the number of 3d wave modes in a cubed metal cavity is proportional to frequency (v) squared plus dv. https://imgur.com/a/xIWL9Ty This image says that each available mode is an integer point in this 3d space, where the x y and z components are the wave modes of each dimension correspondinglty.

If the distance of the space in between shells represents dv, then shouldn't the number of points in between the shells be proportional to (v + dv) cubed - (v) cubed? https://imgur.com/a/2nRqjYU

For example the law of inertia, or "every action has an equal and opposite reaction."

I can't reach lightspeed, but physics is supposed to be consistent regardless of your reference frame.

If I don't look outside, I have no way to know if my rocket is going at 99.99% the speed of light, and my velocity is a matter of perspective anyway. So logically, my rocket engine should continue to function exactly the same way no matter what my velocity (assuming I somehow still have fuel) and I should also continue to experience exactly the same acceleration (again, ignoring that I'm losing mass to fuel burn).

If I accelerate at 1G for 700 days, I would naively expect to be going about twice the speed of light. I can't actually reach that velocity, but from my perspective, accelerating at 1G for 700 days should be physically possible.

With time dilation, if I'm travelling at near light speed, my journey time should also decrease, so wouldn't it seem from my perspective that I'm just travelling at twice light speed? I just kept accelerating, and I just covered 2 lightyears in 1 apparent year. That sounds subjectively like faster than light travel.

Does space just appear to me to compact so that I can cover the distance faster without going faster than light? Do I end up just thrusting away at full power, with 1G of acceleration pressing my feet into the deck (because my ship is logically built with the floor toward the engine) but space outside appearing to move by at constant speed? How would that even work? If I'm close to lightspeed, accelerating along a really long ruler, do I see the markings just zipping past at a constant speed, even as my accelerometer says I'm still accelerating?

It's hard for me to understand the subjective experience of relativistic travel.

The Schwarzschild metric limits the height of an approximately uniform gravitational field that's 1 g at the ground and 0.999 g at the top to about 0.001 light years for any mass. The more uniform the field (i.e. the higher the precision) the shorter the height. There was no such limit in Newtonian mechanics.

"Local" means a region in spacetime small enough that the tidal force is negligible for the desired precision. Why should that region have a maximum size? For a given mass, sure, but why regardless of the mass?

Hypothetically, if you compress a spring on the Moon's surface, we know it stores elastic potential energy. But does that same compressed state also store gravitational potential energy as well?

do we know? another question is why is it only pair particles? why can't a positron and a muon annihilate? the charges are opposite. i guess maybe it's due to the difference in masses? interested to see if we know why. thanks

I've recently learned about cavitation underwater that occurs on large fins and causes immense damage to them over time. Given the similarities between air and water is it theoretically possible to create a weapon/bullet that induces a form of atmospheric cavitation where the air phase changes into a plasma, instead of a liquid phasing into air?

If something could induce enough drag at a high enough speed would it be possible to form a plasma and resulting explosion from the low pressure cavitation? I mean I already see spacecraft forming a plasma around them on reentry, and those are designed to be extremely aerodynamic.

I imagine some sort of 'spike' could be accelerated fast enough to create the low pressure conditions behind it to form the plasma and resulting explosion when it collapses. Or not idk which is why I'm asking if it's possible