What is Relativistic: Definition and 1000 Discussions

Relativistic quantum chemistry combines relativistic mechanics with quantum chemistry to calculate elemental properties and structure, especially for the heavier elements of the periodic table. A prominent example is the explanation of the color of gold: due to relativistic effects, it is not silvery like most other metals.The term relativistic effects was developed in light of the history of quantum mechanics. Initially quantum mechanics was developed without considering the theory of relativity. Relativistic effects are those discrepancies between values calculated by models that consider relativity and those that do not. Relativistic effects are important for the heavier elements with high atomic numbers. In the most common layout of the periodic table, these elements are shown in the lower area. Examples are the lanthanides and actinides.Relativistic effects in chemistry can be considered to be perturbations, or small corrections, to the non-relativistic theory of chemistry, which is developed from the solutions of the Schrödinger equation. These corrections affect the electrons differently depending on the electron speed compared to the speed of light. Relativistic effects are more prominent in heavy elements because only in these elements do electrons attain sufficient speeds for the elements to have properties that differ from what non-relativistic chemistry predicts.

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  1. R

    I Bell's spaceship paradox unknown? Interpretation?

    Recently, I spent some time trying to get an intuitive understanding of special relativity. (I am not a physicist, only took a few physics lectures in the mid-90s) It all went well until I tried to imagine accelerating objects with non-zero length. Specifically, I tried to imagine what a...
  2. LarryS

    I Is Relativistic Action for a beam of light = zero?

    Under the RELATIVISTIC definition of Action, is the Action for a beam of light always zero? Thanks in advance.
  3. S

    B How to add an object's multiple relativistic speeds from x, y, and z?

    Obviously it'd add up to somewhere between 99% and 100% light speed. So how do you figure that out? In the scenario, you reach 99% light speed in one direction, then without slowing, you start to accelerate into an either directly left or right direction (say the engine can rotate without...
  4. Hill

    I Relativistic Lagrangian of a particle in EM field

    I'm following the derivation in Lancaster and Blundell. First, the Lagrangian for the free particle is ##L=-\frac {mc^2} {\gamma}## and the action ##S=\int -\frac {mc^2} {\gamma} \, dt##. Then, EM is "turned on" with the potential energy ##-qA_{\mu}dx^{\mu}##. Then, they say, the action becomes...
  5. M

    A Confused about going from relativistic to non-relativistic Hamilonian

    Hello! My question is related to going from Eq. 32 to Eq. 33 in this paper (however I have seen this in other papers, too). In summary, starting with: $$H \propto \bar{e}\gamma_\mu\gamma_5 e \bar{q}\gamma^\mu q$$ where we have the gamma matrices, e is the electron field and q is the...
  6. StenEdeback

    Classical Looking for book about relativistic classical field theory

    Hi, I am trying to learn relativistic classical field theory as a preparation for studying quantum field theory. I am currently reading chapter 13 i Herbert Goldstein's Classical Mechanics edition 3, but I think that this book is a bit too brief and does not fully derive and explain the...
  7. G

    B Time Dilation: Is This a Reasonable Explanation?

    I thought of this description recently and I think it's pretty intuitive, but I've gotten some side eye telling it to friends and family (maybe because relativity is screwy, maybe because I'm confused, maybe both?) so I want to get some confirmation that it's reasonable. Here goes: If you're in...
  8. Thytanium

    I Inertial Gravity in Relativistic Geodesics - Forum Discussion

    Hello friends of the Forum. I want to ask you why the inertial acceleration in free fall in the relativistic geodesic equations is assumed equal to zero in free fall and equal to 9.8 m/s at rest on the earth's surface. On the other hand, assuming that zero acceleration in free fall, what would...
  9. milkism

    Conservation of relativistic energy, collision of particles

    Question: With maximum do they mean that the speed of the pions is the same as the proton and an antiproton? Otherwise there will be two unknowns, and if I use both relativistic-energy and momentum conservation equations I get difficult equations.
  10. C

    A Multiparticle Relativistic Quantum Mechanics in an external potential

    It is often argued that Dirac Equation is not valid as relativistic quantum mechanics requires the creation of antiparticles. But, there are also some arguments that suggest otherwise. For example, I saw Arnold Neumaier's website on this that there are multiparticle relativistic quantum...
  11. Bastion

    I Does Coulomb’s law change at relativistic speeds?

    Would the force (as predicted by Coulomb’s law) exerted on two charged particles q1 and q2, separated by distance r, and at rest relative to frame S change, if q1 and q2, began moving relative to S but we’re still at rest relative to each other?
  12. S

    Relativistic momentum in terms of another relativisic momentum

    I feel like this should be pretty straightforward knowing all the equations involved but my brain seems be stalling for some reason.
  13. M

    B Relativistic Velocity Addition: Is c Ever Exceeded?

    I was watching this video by Brian Green about relativistic velocity addition when he said something at the end that I wondered about. https://www.britannica.com/video/222286/Your-Daily-Equation-07-Relativistic-Velocity-Combination It was along the lines of the formula will always result in...
  14. K

    Relativity Calculation: Two bodies traveling at relativistic speeds

    Body 1 travels 48 light years from point A to point B at 82% of light speed. Body 2 leaves point A 33 years after Body 1 and travels the 48 light years to point B at 99.99995% of light speed. What I think I know: Body 1 takes 58 years to reach point B according to an earth observer. Body 1...
  15. Al-Layth

    Resource Request for Relativistic Mechanics

    I am aware of the Newtonian model of Gravitation and I am interested in Relativistic Mechanics. I do not know anything about relativistic mechanics other than its more "accurate" at modelling gravitation and that it "reduces" to the classical formulation in some cases. I only want to be able...
  16. L

    I Relativistic length contraction

    Hello! I have a question. If there is a wooden rod which burns certain time, and an astronaut inside rocket lights two such rods: one oriented along the rocket's length and the other goes across the rocket, and an observer see the rocket passing by with a relativistic speed. Will the observer...
  17. R

    A Potential Energy of Relativistic Particles in Coulomb Field

    Let us consider relativistic particle (electron) which moves with relativistic speed ##v## in the Coulomb field (in the field of a fixed heavy nucleus). The main question is what is the potential energy of a particle in such a static field? Landau and Lifshitz in their book "Field Theory"...
  18. More_anonymous

    A Relativistic Relative Velocity Comp.: Bini, D. et al. (1995)

    I'm trying to understand this paper (equation 2.16 specifically): Bini, D., Carini, P., & Jantzen, R. T. (1995). Relative observer kinematics in general relativity. Classical and Quantum Gravity. Am I correct in reading there is no way to express the relativistic relative velocity composition...
  19. StenEdeback

    I Best book for Lagrangian of classical, scalar, relativistic field?

    Hi all experts! I would like to read about the Lagrangian of a classical (non-quantum), real, scalar, relativistic field and how it is derived. What is the best book for that purpose?Sten Edebäck
  20. StenEdeback

    Deduction of formula for Lagrangian density for a classical relativistic field

    Hi, I am reading Robert D Klauber's book "Student Friendly Quantum Field Theory" volume 1 "Basic...". On page 48, bottom line, there is a formula for the classical Lagrangian density for a free (no forces), real, scalar, relativistic field, see the attached file. I like to understand formulas...
  21. BWV

    I Upper limit of relativistic spin?

    Was curious at the upper limit for neutron stars, found this article stating one was found at around 700 / s https://www.newscientist.com/article/dn8576-fast-spinning-neutron-star-smashes-speed-limit/ did not see the size, the article is behind a paywall, but it would have taken a radius of...
  22. G

    B Andy Weir's "Hail Mary": Question About Relativistic Rocket

    I am reading Andy Weir's Hail Mary. There was a part about relativity: it wrote, that a relativistic interstellar ship had lots of spare fuel, because the mission planners actually ignored relativity, and thought travel will be Newtonian. Am i wrong to think, that is nonsense, and the opposite...
  23. B

    Velocity of a relativistic particle in a uniform magnetic field

    d(ɣmv)/dt = qvB (dɣ/dt)mv + ɣm(dv/dt) = qvB Substituting gamma in and using the chain rule, it ends up simplifying to the following: ɣ^3*m(dv/dt) = qvB Now, I am confused on how to solve for v.
  24. atyy

    I Relativistic Bohmian trajectories of photons via weak measurements

    I found out about this interesting paper through a Tweet by Steven Thomson. https://arxiv.org/abs/2108.05169 https://www.nature.com/articles/s41467-022-31608-6 Relativistic Bohmian trajectories of photons via weak measurements Joshua Foo, Estelle Asmodelle, Austin P. Lund, Timothy C. Ralph...
  25. lindberg

    I Relativistic Velocity Addition: Calculating Electron Speed

    If we imagine launching an electron wave in a reference frame S with speed v, should someone viewing the electron from frame S1, which is in inertial motion referring to S, use the relativistic velocity addition to calculate the speed of the electron?
  26. Bruno Cardin

    A Relativistic Hydrodynamics Eqn for Perfect Fluid: Insight Needed

    Hello. Could anyone help me with some insight in an extra term appearing in the motion equations of a relativistic fluid? I say extra term, because it's not present on the motion for a test particle, as it follows: Let's propose Minkowski space-time, the motion equations for a fluid with zero...
  27. vanhees71

    I The general structure of relativistic QFTs

    In a recent thread about Bell tests etc. it has been claimed my point of view of "locality" where "non-mainstream physics". Of course, I cannot give a complete summary of the foundations in a forum posting, as demanded by @DrChinese there. The most clear treatment, particularly emphasizing the...
  28. Adgorn

    Relativistic particle in uniform magnetic field (solution check)

    My solution was as follows: $$\frac {d\overrightarrow p} {dt}=q \frac {\overrightarrow v} {c}\times \overrightarrow B_0$$ The movement is in the ##[yz]## plane so ##|\overrightarrow v\times \overrightarrow B_0|=vB_0##, therefore: $$\biggr |\frac {dp} {dt}\biggr |= \frac {qvB_0} {c}.$$ On the...
  29. LCSphysicist

    Calculate the circumference/diameter in this relativistic problem

    $$ds^2 = dt^2 - r^2 d\theta^2 = d\theta^2((dt/d\theta)^2-r^2) = d\theta^2((1/w)^2-r^2)$$ $$C = \Delta S = \int ds = \int \sqrt{(1/w^2-r^2)}d\theta = 2\pi \sqrt{(1/w^2-r^2)} $$ $$C/2r = \frac{\pi \sqrt{(1/w^2-r^2)}}{r} = \pi \sqrt{\frac{1}{(wr)^2}-1}$$ But this answer is wrong. And i don't know...
  30. P

    I Exploring a Flat, Expanding Universe with GR & Newtonian Mechanics

    Global Newtonian mechanics seems to be compatible with 1) Hubble's law, and 2) the cosmological principle: take a vector space, set the velocity of a galaxy at x to be v=x, where x is the position vector. Then from any galaxy, the other galaxies seem to go away with velocity v2-v1 = x2-x1. That...
  31. F

    I How to define expectation value in relativistic quantum mechanics?

    In non relativistic quantum mechanics, the expectation value of an operator ##\hat{O}## in state ##\psi## is defined as $$<\psi |\hat{O}|\psi>=\int\psi^* \hat{O} \psi dx$$. Since the scalar product in relativistic quantum has been altered into $$|\psi|^2=i\int\left(\psi^*\frac{\partial...
  32. Arman777

    A Relativistic Redshift and understanding it's approximation

    I was reading an article, and I saw this expression. $$ 1+z=\frac{(g_{\mu\nu}k^{\mu}u^{\nu})_e}{(g_{\mu\nu}k^{\mu}u^{\nu})_o} $$ Where ##e## represents the emitter frame, ##o## the observer frame, ##g_{\mu\nu}## is the metric, ##k^{\mu}## is the photon four-momentum and ##u^{\nu}## is the...
  33. F

    I What is the role of Relativistic QM?

    In non-relativity then there is QM, but in relativistic regime then there is QFT. Then what is useful role of Relativistics QM nowaday, or it is only has a historical meaning?Does non-existance wave function in relativistic regime make RQM meaningless?
  34. S

    Relativistic correction to Coulomb Potential in SQED

    I have derived the Coulombian potential as an effective potential between two spinless charged particle taking the non-relativitic approach on the scattering amplitude obtained in terms of the Feynman rules in SQED. The scattering amplitudes are: I'm using the gauge in which xi = 1. How could...
  35. J

    B How do relativistic effects change oscillation of the balance wheel in mechanical watch causing it to tick slower?

    Does mechanical watch ticks slower when move fast, due to relativistic effects? To make watch tick slower you must change oscillation of balance wheel inside watch, so if answer is yes, what myster "force" change balance wheel oscillation in mechanical watch to ticks slower?
  36. hutchphd

    B Exploring Relativistic Mass & Length to Help STEM Students

    Comments please Is there good sobriquet to use for relativistic length ? Just a thought to aid the struggling college frosh STEM students
  37. A

    I Relativistic Doppler Effect near a Black Hole

    Hey everyone, if I were to view a shining person rotating near a black hole at near the speed of light there would be 2 kinds of redshifts: gravitational redshift and relativistic doppler effect redshift. Right? But, say at some point, the person is traveling towards me, then the doppler effect...
  38. J

    I Can Relativistic Matter Exist At Absolute Zero? - Explained

    If it were possible to obtain absolute zero, could relativistic matter exist when classical momentum would be zero? Would a particle cease to exist? I can't do the math. Thank you for reading my question.
  39. stevendaryl

    I A short derivation of the relativistic forms of energy and momentum

    I've been noodling around with derivations of the relativistic energy and momentum, and I almost got it down to just a few lines. But not quite. I'm going to work in one spatial dimension, for simplicity (even though some derivations require a second spatial dimension) Let's assume that there...
  40. M

    I General relativistic comparison to Newtonian physics

    Let's say a small object orbits around massive object at some distance in perfectly circular orbit. In Newtonian physics the force acted upon orbiting body is: Force = m1 * orbital_speed^2 / distance = G * (m1*m2) / r^2 for an object of 1kg orbiting a body of 2*30^kg at the distance of 1.521 *...
  41. O

    Compute relativistic addition of velocities

    edit: I had a sign error that is now corrected, no further help needed. Consider in the laboratory frame one second passing. Let ##(t,x)## be the coordinates of various events in a spacetime diagram. Both particles are released at ##(0,0)## Then after one second the left moving particle is at...
  42. B

    B Exploring Relativistic Thermodynamics Experiments

    In most experiments of SR, we look at atomic and subatomic particles or the frequency of EM radiation. The Haefele-Keating experiment looked at the resonance of cesium atoms stimulated by a certain EM frequency https://en.wikipedia.org/wiki/Hafele–Keating_experiment The Ives-Stillwell...
  43. greg_rack

    B How does special relativity apply to the rocket equation?

    Hi guys. I am studying the relativistic implementation of the standard Tsiolkosvky rocket equation, but ran into some doubts. Doesn't special relativity apply only to inertial frames of reference(non-accelerated)? Then, how could it be used for the rocket equation, which speaks of a ##\Delta...
  44. greg_rack

    B Relativistic rocket equation

    I am studying through online resources some principles of spacecraft propulsion, since it really fascinates me, and makes me want to know a bit more about it :) For rockets, thruster, I found the Tsiolkovsky rocket equation: $$\Delta v=v_e ln(\frac{m_0}{m_f})$$ Of course, rockets can travel...
  45. H

    The relativistic Doppler effect

    I found the observed frequency from the energy. Then I used the receding Doppler shift formula to find, the source frequency but after that when i tried to use the Rydberg equation I got a value for the energy level less than one. and I'm pretty sure my work is right, any help is greatly...
  46. greg_rack

    B How to relate relativistic kinetic energy and momentum

    Hi guys, a special relativity problem requested to choose the right graph representing relativistic momentum ##p## as a function of rel. kinetic energy ##K##, from these four: At first, I tried writing ##p## as a function of ##K##, in order to then analyze the function's graph and see if it...
  47. A

    Do relativistic effects make the age of the universe moot?

    How can we know the age of the universe, with time dilation due to the mass and velocity of matter which condensed after the big bang. If time passes at different speeds depending where it is perceived, does this not make the age of the universe somewhat moot.
  48. Mayan Fung

    I Refractive index of a medium in relativistic motion

    I once naively think that the speed of light is also a constant in a medium in all inertial frames which is not the case. I tried to derive the result yet there is a discrepancy from the results I read in some articles. For example, from [Link to unpublished paper redacted by the Mentors], the...
  49. E

    Speed of sound in a relativistic fluid

    Let us consider the co-moving observer ##\mathscr{C}## for whom ##E = \epsilon## and ##\mathbf{\vec{V}} = \mathbf{\vec{0}}##. Doing the perturbation stuff to the first of the relevant equations gives$$\partial_t \delta \epsilon + \boldsymbol{\nabla} \cdot ([\epsilon + p] \delta \mathbf{\vec{V}})...
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