Centre of mass decoherence due to time dilation: paradoxical frame-dependence

The beam scattering method was used to investigate non-dissociative single-electron charge transfer between the molecular dication CO22+ and Ar or Ne at several collision energies between 3-10 eV (centre-of-mass, c.m.). Relative translational energy distributions of the product ions showed that in the reaction with Ar the CO2+ product was mainly formed in reactions of the ground state of the dication, CO22+(X3Σg-), leading to the excited states of the product CO2+(A2Πu) and CO2+(B2Σu+). In the reaction with Ne, the largest probability had the process from the reactant dication excited state CO22+(1Σg+) leading to the product ion ground state CO2+(X2Πg). Less probable were processes between the other excited states of the dication CO22+, (1∆g), (1Σu-), (3∆u), also leading to the product ion ground state CO2+(X2Πg). Using the Landau-Zener model of the reaction window, relative populations of the ground and excited states of the dication CO22+ in the reactant beam were roughly estimated as (X3Σg):(1∆g):(1Σg+):(1Σu-):(3∆u) = 1.0:0.6:0.5:0.25:0.25.

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The Equivalence Principle

10.1093/oso/9780199658633.003.0013 ◽

2018 ◽

Author(s):

David M. Wittman

Keyword(s):

General Relativity ◽

Special Relativity ◽

Equivalence Principle ◽

Time Dilation ◽

Gravitational Redshift ◽

Coordinate Systems ◽

Spacetime Metric

The equivalence principle is an important thinking tool to bootstrap our thinking from the inertial coordinate systems of special relativity to the more complex coordinate systems that must be used in the presence of gravity (general relativity). The equivalence principle posits that at a given event gravity accelerates everything equally, so gravity is equivalent to an accelerating coordinate system.This conjecture is well supported by precise experiments, so we explore the consequences in depth: gravity curves the trajectory of light as it does other projectiles; the effects of gravity disappear in a freely falling laboratory; and gravitymakes time runmore slowly in the basement than in the attic—a gravitational form of time dilation. We show how this is observable via gravitational redshift. Subsequent chapters will build on this to show how the spacetime metric varies with location.

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Energy and Momentum

10.1093/oso/9780199658633.003.0012 ◽

2018 ◽

Author(s):

David M. Wittman

Keyword(s):

Time Dilation ◽

Speed Of Light ◽

Massless Particles ◽

The Everyday ◽

Low Speeds ◽

Energy And Momentum ◽

Deep Relationship ◽

Insight Into ◽

Momentum Relation

Tis chapter explains the famous equation E = mc2 as part of a wider relationship between energy, mass, and momentum. We start by defning energy and momentum in the everyday sense. We then build on the stretching‐triangle picture of spacetime vectors developed in Chapter 11 to see how energy, mass, and momentum have a deep relationship that is not obvious at everyday low speeds. When momentum is zero (a mass is at rest) this energy‐momentum relation simplifes to E = mc2, which implies that mass at rest quietly stores tremendous amounts of energy. Te energymomentum relation also implies that traveling near the speed of light (e.g., to take advantage of time dilation for interstellar journeys) will require tremendous amounts of energy. Finally, we look at the simplifed form of the energy‐momentum relation when the mass is zero. Tis gives us insight into the behavior of massless particles such as the photon.

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Evaluation of a simple characterisation method of the 3D-position of a manual wheelchair centre of mass

Computer Methods in Biomechanics & Biomedical Engineering ◽

10.1080/10255842.2020.1815328 ◽

2020 ◽

Vol 23 (sup1) ◽

pp. S172-S174

Author(s):

J. Loisel ◽

J. Bascou ◽

Y. Poulet ◽

C. Sauret

Keyword(s):

Centre Of Mass ◽

Manual Wheelchair

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Small changes in ball position at address cause a chain effect in golf swing

Scientific Reports ◽

10.1038/s41598-020-79091-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sung Eun Kim ◽

Jangyun Lee ◽

Sae Yong Lee ◽

Hae-Dong Lee ◽

Jae Kun Shim ◽

...

Keyword(s):

Ground Reaction Force ◽

Reaction Force ◽

Statistical Parametric Mapping ◽

Golf Swing ◽

Whole Body ◽

Centre Of Mass ◽

Body Segment ◽

A Chain ◽

Professional Golfers ◽

The Right

AbstractThe purpose of this study was to investigate how the ball position along the mediolateral (M-L) direction of a golfer causes a chain effect in the ground reaction force, body segment and joint angles, and whole-body centre of mass during the golf swing. Twenty professional golfers were asked to complete five straight shots for each 5 different ball positions along M-L: 4.27 cm (ball diameter), 2.14 cm (ball radius), 0 cm (reference position at preferred ball position), – 2.14 cm, and – 4.27 cm, while their ground reaction force and body segment motions were captured. The dependant variables were calculated at 14 swing events from address to impact, and the differences between the ball positions were evaluated using Statistical Parametric Mapping. The left-sided ball positions at address showed a greater weight distribution on the left foot with a more open shoulder angle compared to the reference ball position, whereas the trend was reversed for the right-sided ball positions. These trends disappeared during the backswing and reappeared during the downswing. The whole-body centre of mass was also located towards the target for the left-sided ball positions throughout the golf swing compared to the reference ball position, whereas the trend was reversed for the right-sided ball positions. We have concluded that initial ball position at address can cause a series of chain effects throughout the golf swing.

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Time Dilation and Contraction for Programmable Analog Devices with Jaunt

ACM SIGPLAN Notices ◽

10.1145/3296957.3173179 ◽

2018 ◽

Vol 53 (2) ◽

pp. 229-242

Author(s):

Sara Achour ◽

Martin Rinard

Keyword(s):

Time Dilation ◽

Programmable Analog

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Utilizing relativistic time dilation for time-resolved studies

The Journal of Chemical Physics ◽

10.1063/5.0037862 ◽

2021 ◽

Vol 154 (11) ◽

pp. 111107

Author(s):

Hazem Daoud ◽

R. J. Dwayne Miller

Keyword(s):

Time Dilation ◽

Time Resolved ◽

Relativistic Time

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Measurement of the shape of the $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ differential decay rate

Journal of High Energy Physics ◽

10.1007/jhep12(2020)144 ◽

2020 ◽

Vol 2020 (12) ◽

Author(s):

R. Aaij ◽

◽

C. Abellán Beteta ◽

T. Ackernley ◽

B. Adeva ◽

...

Keyword(s):

Decay Rate ◽

Form Factors ◽

Proton Collision ◽

Centre Of Mass ◽

Mass Energy ◽

Proton Proton ◽

Lhcb Detector ◽

Proton Proton Collision ◽

Integrated Luminosity

Abstract The shape of the $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ B s 0 → D s ∗ − μ + ν μ differential decay rate is obtained as a function of the hadron recoil parameter using proton-proton collision data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb−1 collected by the LHCb detector. The $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ B s 0 → D s ∗ − μ + ν μ decay is reconstructed through the decays $$ {D}_s^{\ast -}\to {D}_s^{-}\gamma $$ D s ∗ − → D s − γ and $$ {D}_s^{-}\to {K}^{-}{K}^{+}{\pi}^{-} $$ D s − → K − K + π − . The differential decay rate is fitted with the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) parametrisations of the form factors, and the relevant quantities for both are extracted.

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