#specialrelativity — Public Fediverse posts

Reading Project Hail Mary and -- controversial opinion here folks -- it's pretty good.

Trying to avoid the movie because I don't wanna be picturing Ryan whoever when I read about Grace. I'll watch the movie when I'm done.

Hey, guess what, the book made me curious about #RindlerCoordinates https://en.wikipedia.org/wiki/Rindler_coordinates

#SpecialRelativity #ProjectHailMary

@level98

Hi Theo,

thanks for your replies.
First of all, however, I'd like you to know that I managed to get a copy of your Austr. Phys. 56 (6), 2019, thanks to your website and the excellent archive of the AIP.

Interesting article! While your repeated attempts to "save [parts of] that oft-used [abominable] phrase" didn't succeed, I was very glad that you -- almost in passing -- struck upon **the** **appropriate** phrase:

> _»We know that it is you [circled Y in Fig. 1] who measures the proper time, and hence the shorter time interval.«_

So the key/solution is: to refer to **duration**, certain clocks running **longer** (or **shorter**) than certain other clocks;
instead of referring to clock rate (frequency), i.e. certain clocks running faster (or slower) than certain others.

This holds for #GeneralRelativity just as well.

All that inappropriate referring to clock rate has been nothing but a "red hering" from the outset (Einstein Ann. Phys. 17, 891 (1905))!

In terminology I prefer, I teach the Fig.1-applicable appropriate #SpecialRelativity phrase as

"The duration of Y, from having met/passed R until having met/passed L,
is shorter, by factor √{ 1 - β^2 }, than
the duration of R, from having met/passed Y
until R's indication simultaneous to L's indication of having met/passed Y."

p.s. For your kind consideration, here's "putting my money where my mouth is": https://scirate.com/arxiv/2605.21660

p.p.s. The notion #Duration may have been depreciated in #Relativity due to nonsense by the French philosopher H. Bergson. Instead, "duration" plainly is in the SI-second-def

p.p.p.s. I can mostly recommend tooting (!) by mathstodon: 1729 chars. + \(\LaTeX\) -- only "Markdown" still doesn't work!

Mass Shell

https://elkement.art/2026/07/02/mass-shell/

https://mastodon.social/@level98/116790991658848783

@level98

Level 98 wrote (22. Juni 2026, 02:45):
> the words "moving clocks run slow" is a *terrible* phrase talking about #relativity.

Agreed.

Who would ever distort into such an abomination a perfectly legitimate standard phrase such as, say

"clock \(A\) has run _slower_, i.e. at lower clock rate \(\nu_A\), on average, on its (time-like) worldline segment starting from event \(\varepsilon_{ABJ}\) and ending with event \(\varepsilon_{ABK}\)
than
\(\nu_B\), the rate clock \(B\) has run, on average, on _its_ (time-like) worldline segment starting (likewise) from event \(\varepsilon_{ABJ}\) and ending (likewise) with event \(\varepsilon_{ABK}\)"
?

> The reality of SR is far cooler and (according to a teacher I was helping) easier to understand, if one doesn't use such pop sci phrases.

How else could you even begin to communicate (e.g. to students) that, accordingly, a comparison is to be made between

- the ratio \(\nu_A := \frac{(t_A[ ~ \text{_BK} ~ ] - t_A[ ~ \text{_BJ} ~ ] )}{ \tau A[ ~ \text{_BK}, \text{_BJ} ~ ]}\)

and

- the ratio \(\nu_B := \frac{(t_B[ ~ \text{_AK} ~ ] - t_B[ ~ \text{_AJ} ~ ] )}{ \tau B[ ~ \text{_AK}, \text{_AJ} ~ ]}\)

?

p.s.
Did you (or that fine teacher you mentioned) come up with a more efficient notation for identifying

- distinctive events (by the names of their distinguishable coincident participants),

- distinctive indications of any one participant (by the names of all other distinguishable participants coincident in the resp. event),

- the (not necessarily distinct) readings "t" assigned to indications,

- the durations (a.k.a. arc-lenghts) \("\tau"\) of specific worldline segments
?

For #SpecialRelativity and in general.

#Physics #SpecialRelativity Just a reminder that the words "moving clocks run slow" is a *terrible* phrase to use in talking about relativity.

It confuses students, teachers, the general public etc.

The reality of special relativity is far cooler and (according to a teacher I was helping) easier to understand, if one doesn't use such pop sci phrases.

Physicists propose that our universe may contain three dimensions of time

Space and time looked settled, at least in broad outline. Einstein’s special relativity gave physics a durable framework…
#NewsBeep #News #Physics #AndrzejDragan #CA #Canada #ClassicalandQuantumGravity #dimensions #lightspeed #PrincipleofRelativity #quantumbehavior #Science #specialrelativity #superluminalmotion
https://www.newsbeep.com/ca/716296/

Anyone here able to explain a formula in Wikipedia about the Tolman Paradox?

https://en.wikipedia.org/wiki/Tachyonic_antitelephone#Two-way_example

The t' definition is a mystery to me. How would we drop in c to get the unit of time? How come a is multiplied with v?

#physics #specialRelativity #tolman #einstein

Your driving a car at 100 km/h. Someone passes you doing 10 km/h relative to you.

So they're driving at 110 km/h?

Yes... and no.

Simply adding velocities is a Galilean transformation between your frame of reference and the road's - the relativity of Newtonian mechanics (Newts three laws etc.)

However, turns out to be incorrect... negligibly noticeable here, very noticeable for relative speeds "near" the speed of light.

Just one fascinating consequence of SR.

#Physics #SpecialRelativity

#Physics #SpecialRelativity I'm about to, yet again, run an online course in Special Relativity (SR) for high school physics teachers. I was going to say "local" but I have two from interstate (WA), and even two from NZ!

I was wondering if there's something *you* don't understand / are confused about, and would like to ask, related to basics of SR (no acceleration / high school level) - "my students" might also want to know!

[Note: answering on social media has limits, but I'll try my best.]

Special Relativity: When you move a clock, it is slower as when it just sits there. When stopped, it runs with the normal speed again. (All relative to the non-moving observer.)

How's that? There are explanations out there, but wrote it down myself to understand it better.

For fun, I added a calculator to see how bad it can get. 4 hours in a plane and your clock lags ~4 nanoseconds (ignoring gravitation).

https://miamao.de/blog/2026-01/22.Moving_Clocks_In_Special_Relativity.html

#physics #specialRelativity #twinParadox #lightClock

How does the Twin Paradox work in Special Relativity? There are gazillion more or less correct and useful descriptions out there.

Everyone has their preferred one. Like in University many years ago, I grok things best if I describe them in my own words. So here we go:

https://miamao.de/blog/2026-01/11.Twin_Paradox_Explained_with_the_Light_Clock.html

#specialRelativity #twinParadox #lightClock #miamao_de

RE: https://mastodon.murkworks.net/@wrog/115860196660746312

Roger's having another go at explaining special relativity without complex maths. ^_^

#physics #science #Explainer #SpecialRelativity #relativity

#Physics I encountered this misleading throwaway about #SpecialRelativity again the other day:

"We move through spacetime at speed c."

I like that, at the same time, I also discovered someone had written a paper about it, titled:

"Do Objects Move Through Space-Time at the Speed of Light? No."

It'd be an example of "Betteridge's law of headlines" except, perhaps, for the "No" at the end, which I love! 😀 More MSM articles should do that. 1/4

https://pubs.aip.org/aapt/pte/article-abstract/62/8/648/3317767/Do-Objects-Move-Through-Space-Time-at-the-Speed-of?redirectedFrom=PDF

Mass isn't fundamental - it's momentum you can't see in a fifth dimension.

New paper: particles are massless 5D objects. Mass = ℏk_W/c (momentum along W-axis).

Time dilation? Reduced W-oscillation when 3D velocity increases.

Entanglement? Particle-antiparticle pairs are opposite ends of a single 5D spinor.

E² = p²c² + m²c⁴ emerges automatically.

🔗 https://zenodo.org/records/17922219

@fqxi @Physics

#physics #QuantumMechanics #SpecialRelativity #TheoreticalPhysics #openscience #preprint

Ever wondered how time slows near a black hole?
Compare how time flows near stars, planets & black holes interactively.
Try it now: https://stellarsnap.space/time-dilation

#TimeDilation #Relativity #BlackHoles #Physics #Astronomy #Science #Astrophysics #Einstein #SpaceTime #GeneralRelativity #SpecialRelativity #Cosmos #SpacetimeCurvature #Gravity #SpaceTools #StellarSnap

The above, the below and the lack of relativity between them #art #illustration #quantummechanics #specialrelativity

I've just viewed a lecture from Carlo Rovelli, an Italian physicist, about the theories of TIME. It was a fascinating lecture to hear. Frankly, it all made sense and I can't wait to get hold of his book :The Order of Time.
#Physics #QuantumMechanics #NewtonianSpace #QuantumGravity #Neurology #SpecialRelativity #SpaceTime #ArrowOfTime

There's a #misconception about the #timespace speed limit, the speed of light. It seems that if you're determined to travel to another galaxy you won't live to see it. But the truth is that you can actually travel arbitrarily fast, if you only consider the on-board, local time. If you forget what you're leaving behind, you can go anywhere as fast as you go. The Lorentz transform will take care of everything. You can get to Andromeda in a day. You can get there in a minute. Just need to go faster. Lorentz contraction will take care of it. You can get there in a second. You can go arbitrarily fast! The outside observer will see you frozen in time when traveling.

#physics #relativity #specialrelativity

This is an old animation I had on VHS. I animated the train part (30 yrs ago?) with Mathematica on my NeXTdimension cube (using the graphic board NTSC Composite outputs). I renumerized it back from tape lately and added the scrolling text. Et aujourd'hui j'ai accolé l'intro musicale. Reste plus qu'à mettre des bips bips sonores lors de l'arrivée des impulsions lumineuses dans la partie 'train'...

#Physics #Einstein #SpecialRelativity #Classroom #PhysicsEducation #NeXTcomputers

Queen '39 - Physics (Time Dilation)

> For so many years are gone
> Though I'm older but a year
> Your mother's eyes from your eyes cry to me

#OddNobelPrizeASongOrPoem
#HashTagGames
#TimeDilation
#SpecialRelativity
#Physics
#BrianMay

#Physics #SpecialRelativity Consider two relatively moving inertial reference frames (IRFs) A and B. You can select two Events for which A and B measure the *same* time interval between the two Events.

"What?" you say "But shouldn't there be time dilation?... shouldn't one measure the time interval as greater than the other?"

The time dilation equation is just one small part of a bigger picture.

As an exercise for the reader:

1/2

#Physics #SpecialRelativity

For anyone who has never come across them (or for those who have forgotten) "Reflections on Relativity" is a fantastic free resource (also available as a book) that discusses foundational etc. aspects of Special and General Relativity.

Probably not a great resource for learning from(?) but a great read if you already understand a reasonable amount. There's also some other good reads / references to his books on Math Pages website.

https://www.mathpages.com/rr/rrtoc.htm

#Einstein’s Journey to the Second #Postulate of #SpecialRelativity : Medium

#SpaceForce’s #Mysterious X-37B is testing its ‘#Aerobraking’ : Pop Sci

How the Famous #Lucy #Fossil Revolutionized the Study of #HumanOrigins : Sci Am

Check our latest #KnowledgeLinks

https://knowledgezone.co.in/resources/bookmarks

My #cat demonstrates #specialrelativity

#physics #einstein #relativity

@NSFVoyager2

Rick: Sam?
Sam: Yes, boss.
Rick: If it's December 1941 in Casablanca, what time is it in New York?
Sam: What? My watched stopped.
Rick: I bet they're asleep in New York. I bet they're asleep all over America.

#specialrelativity 😊

#Physics You're standing on a platform at a train station and a train passes through the station at a significant fraction of the speed of light.

You can see a large clock on the front of the train as it comes towards you. The clock looks like it's running much faster than your watch.

You can see a clock on the back of the train as the train moves away from you. That clock appears to be running much slower than your watch.

#SpecialRelativity

A Brief Crash Course on #TimeTravel
excerpt from #PopularMechanics by Matt Blitz

…"In the 1680s, Sir #IsaacNewton thought time progressed at a consistent pace throughout the #universe, regardless of outside forces or location …
In 1905, #Einstein revealed his ideas on #specialrelativity … that time is elastic and dependent on speed, slowing down or speeding up depending on how fast an object—or person—is moving"…

🔗 https://PopularMechanics.com/science/math/a20718322/building-a-time-machine/ 28 Dec 2022

#Time #Timelessness #TimeTravelTheory