swansont

Who made the accusation?

! Moderator Note You have to post the material you wish to discuss. Not just a link to it. See rule 2.7

! Moderator Note Moved out of the Lounge because this is not a “Lounge” topic

Right. it’s a separate effect, and as such, not part of relativity. You account for the effects independent of relativity, because they manifest themselves independently You don’t care if a clock appears smaller, and we know that the visual size is not the measured size. As has been pointed out, what you see and what you measure are not the same, and it’s time you stopped interchanging the two. Perhaps, but this confirms that you can handle the concept of something visually looking longer or shorter does not mean that its measured length has changed.

B would see X as length-contracted (not that he can actually see through the planet to notice this), and also see planet X (that is 1 LH away according to A) as being only 0.6 LH away. According to B's clock, the trip will take 45 minutes. According to A's clock it will take an hour and fifteen minutes. All of this has been explained, multiple times, starting with Janus in the fourth post of the thread. It's not going to change.

So the concern is getting salmonella from food, and yet you don't want the food to be treated to reduce the risk from salmonella... In any event, not all US chickens are treated this way, and surely individual transactions can be arranged so that the imported chickens are untreated. AFAIK trade agreements simply define the parameters and regulations of commerce, they aren't the actual commercial transaction. The agreement might allow for chlorine treatment, but does it mandate it? If <UK food conglomerate> wants to import chicken from <US chicken packager>, they can agree to any details not forbidden by the applicable laws. You don't want chlorine treatment? Put it in the contract. To use an example, it seems to me you could import kosher or halal products, which would demand the products were prepared in accordance with the appropriate procedures, above and beyond any basic trade agreement. I suspect that would make food poisoning worse, not better...

Not attempted because we can't get stuff that massive to move that fast. But we've done the equivalent in particle accelerators, as Halc has said. if you get a proton up to 1 TeV, it should be moving about 45x the speed of light according to Newtonian physics. The easiest effect to measure is on time, and we have done multiple tests that confirm relativity, the most obvious of which is GPS. That you are ignorant of the experiments and technologies that confirm it carries no weight in any discussion. This is criminally naive. ! Moderator Note Split from original thread, which was asking about Newtonian physics. Hijacking, and also an argument not made in good faith. Please stop doing that.

But the earth isn't closer when you are 1 LH away. The light doesn't "remember" where it came from. This is a geometry/perspective issue, not one of relativity. They are distinct effects and have to be treated as such. The perspective issue should be easy to incorporate and separate from analysis, because it's an everyday effect. But it doesn't go away simply because of relativity. In fact, almost all of this discussion could be done with examples at slow speeds, allowing us to ignore relativity completely. Then it becomes simple everyday effects, and the misconceptions based on those effects could theoretically be cleared up.

The earth doesn't "know" where an observer is. The lights leaving the earth doesn't care about any potential observers. It will spread out, decreasing in intensity with approximately a 1/r^2 dependence. The earth will look smaller to the observer as they move away. The thing that the delay will affect is if there is an event. If there is an explosion, the observer will not notice until the light gets to them. Events happen at particular times. But the earth just sitting there sends out the same signal continuously. Only time-tagged events will be affected by the delay.

That there are no preferred frames, so that all measurements are equally valid, is based on one of the postulates of relativity. To deny that is to deny the validity of relativity, and there really isn't any "interpretation" that gets you around this.

There is a delay, which they both see. The light from the earth takes an hour to get to the traveler. But the light is continuously sent. It's not sent every hour, like the clock signals everyone has discussed. But you identified two delays - the light travel time, and the delay before the twin sees the earth getting closer, after turnaround. The first exists. The second does not. If you go 1 LH away and stop, you will get light that was sent from earth an hour earlier. If you turn around and go back, when you've moved 1 LS, you will get light that left the earth 59 minutes and 59 seconds ago.The earth will take up an incrementally larger solid angle on your screen (assuming sufficient resolution) because you are closer to the source. There is no delay in noticing this; that light was already en route.

People have a right to ignore you. Writing bans off as being tied to political correctness is a cop-out, IMO, for people behaving or wanting to behave like an a-hole but not suffer consequences for it. People asserting opinions as if they are facts, or trying to shield shoddy “facts” as if they were opinion. Just running away from accountability

No. A signal will take an hour to get there, but light is continuously sent. The traveler will immediately see the earth get closer, from photons emitted an hour (or slightly less) earlier Disagreeing without scientific justification. If you think there is a delay, show the math.

! Moderator Note We require more rigor than you’ve been providing, so please, do not open a new thread if it’s going to be like this one: assertion with no science to back it up. Don’t open a new thread in this topic, either

And the delay can be accounted for, as has been explained a dozen times. There's nothing magical about it. It's just math. (it's not really different than realizing that if you kick the ball to where someone is right now, but they're running, it will miss. You kick the ball to where they will be - you take into account the time it takes the ball to travel) Miss? How can it miss? It goes out and comes straight back. It's a 1-dimensional example That's a huge part of the problem here. Janus gave a correct explanation. The traveling twin does not miss the earth on the return trip. To add to this: The thing everyone agrees on are events. If something happens in one frame, it happens in all frames. But they will not agree on certain measurements: time, distance, energy, etc. since those depend on your frame of reference. If there are two events, observers might not even agree on which one happened first.

! Moderator Note Can we stick to the topic, please? (no responses required)

Why is the outbound trip one hour but the return is 30 minutes, according to the traveler’s clock? How is that possible?

It’s been taken care of.

Which is what happens, as long as the situation is symmetric. The distances are not the same, but that part of the scenario is not symmetric. One of them is moving relative to the turnaround location, but the other is not. But each does observe length contraction, of an equal factor, of any frame that is in motion Of course there is. Acceleration is not inertial, and not symmetric. This is not true. Acceleration is not inertial. That’s true up until B turns around. Arrival at the turnaround. (But given that you don’t understand relativity, making the example more complicated is a losing proposition.) B undergoes an acceleration, which is not inertial and destroys the symmetry of the problem. Things aren’t wrong just because you can’t figure it out. That’s a fallacy - argument by personal incredulity.

You were talking about the twin’s dimensions. Not the same thing. Bufofrog explained how the length contraction “accumulates” - the distances you traverse are shortened as long as you travel. That distance will be shorter as measured by someone in a different frame, and the difference in those values increases as the duration of the trip increases.

Welcome to physics. Everything we do involves a model, as we try to understand how nature behaves.And we have a pretty decent handle on how light behaves. Knowing what something “actually is” is in the realm of philosophy (it’s metaphysics).

Comes back to his original dimensions as measured by the other twin (any statement like this has to say in what frame the measurement is being made) The frequency of his clock reverts, too. The accumulated time difference remains. On the contrary, your questions have been answered numerous times. Please don’t pretend otherwise. You have not absorbed the information, unfortunately. Part of the problem is that when one jumps into the middle of a complex problem without understanding the basics, it usually doesn’t go very well. Another issue is avoiding the mathematical underpinnings. That’s philosophy (metaphysics), so you won’t get an answer in a physics thread, other than some variation of “time is what is measured by a clock” Yes. You have preconceived notions which are wrong, and refuse to abandon them. Instead, you try and fit things into your view, and that invariably fails, because nature doesn’t behave as you think it does, or want it to.

“Justice Ruth Bader Ginsburg, the demure firebrand who in her 80s became a legal, cultural and feminist icon, died Friday. The Supreme Court announced her death, saying the cause was complications from metastatic cancer of the pancreas.” https://www.npr.org/2020/09/18/100306972/justice-ruth-bader-ginsburg-champion-of-gender-equality-dies-at-87?utm_source=dlvr.it&utm_medium=twitter

When he returns the relative speed is zero, so no. Their clock run at the same rate, too, at that point. Length contraction and time dilation require motion (for SR). But during trip, yes, he is, according to the twin on earth. As is his spaceship. Reality has nothing to do with it. A billion different answers from a billion observers, and none of them can do a physics experiment that shows that “this is the ‘real‘ frame” Each frame is as real as the next. But I can’t cause a force to be exerted somewhere simply by moving. There’s so force, and rigidity is not an issue. Nothing is being crushed. A meter stick, or a length of a meter, is not a meter long when measured from a moving frame. Energy isn’t invariant, either. If you’re on a train car moving 100 m/s and throw a 1 kg ball 10 m/s, you see the ball moving 10 m/s and have 50 joules of KE. That’s true for anyone on the train. But that ball hitting a wall affixed to the earth is moving 110 m/s and has 6050 joules. Which one is “real”? Values depending on which frame you’re in is nothing unusual in physics. No, it isn’t. “Reality” is not anything relativity distinguishes Younger than his twin, because time ran slower for them. Not younger than when they started. And yes, the effect is real, in that it is not an illusion. Clocks would read different times.

Who is forcing grandma to get in the car, against her will, without her regard for risk? Aren’t they the immoral one? If she drives of her own volition and accepts the risk, where is the immorality? She made the choice.