Why are Galilean and Lorentz transformations not equivalent at low speeds?

When analyzing a moving body with respect to a moving observer we can use the Galilean or Lorentz transformations. As we approach the speed of light we know the Lorentz transformation gives the...

10 November 2017 6,522 10 View

Can the one-way speed of light be measured using entangled photons?

08 September 2015 1,710 5 View

Is energy conserved for moving observers?

Imagine a pendulum swinging back and forth. When it is at its lowest point the PE = 0 and KE is maximal. Now imagine an observer moving along in the direction of the pendulum, with matched...

10 November 2014 498 1 View

Does accelerated charge emit photons to all observers?

We know that a decelerated charge emits photons. So you can visualize an observer in a stationary frame of reference that detects these photons. However for another observer in an accelerated...

10 November 2014 1,538 26 View

Are there any organisms that don't get cancer?

Are there any multicellular life forms that don't get cancer or where cancer is very rare?What can we learn from these cases?

06 July 2014 867 10 View

How many uncertainty relationships are there?

06 July 2014 1,951 8 View

Why does resolution depend on wavelength?

We all know the resolution depends on wavelength. However, when a student sees this concept for the first time it does seem paradoxical. After all, the direction in which the wavelength is...

05 June 2014 6,153 4 View

Why do TEM modes have no low-frequency cut-off?

For TEM modes, H_z = 0 and E_z = 0, so we can easily find from Maxwell's equations that TEM modes in, say, coax have no low-frequency cut-off. The TEM modes are dispersionless and exist from the...

05 June 2014 8,368 3 View

Can anyone explain how a wine glass resonates at a wavelength bigger than the glass?

a) See here: https://www.youtube.com/watch?v=BE827gwnnk4 b) It takes 300 Hz to break a wine glass c) Speed of sound in air = 340 m/s d) Wavelength = 340/300 = 1.13 metres e) Speed of sound in...

04 May 2014 6,003 10 View

Do the number of electromagnetic modes in a coax cable depend on its length?

In a recent paper it has been stated: "It is true that TEM wave modes in a [coax] waveguide do not have a low-frequency cut-off versus the diameter of the [coax] waveguide, but this argument is...

04 May 2014 4,245 46 View

error in running a model in Abaqus

Excessive rotation of nodes in node set ErrNodeExcessRotation-Step1

17 August 2021 0 0 View

error in modelling model in Abaqus

Excessive rotation of nodes in node set ErrNodeExcessRotation-Step1

17 August 2021 0 0 View

MGL tools

20 June 2021 0 0 View

what is the simplest definition of ion exchange capacity

What this unit identifies for the ion exchange capacity ca. 0.92 meq. g-1. I am a newcomer in the membrane area. I just started. I highly appreciate your help

08 May 2021 0 0 View

what is the simplest definition of ion exchange capacity

What this unit identifies for the ion exchange capacity ca. 0.92 meq. g-1. I am a newcomer in the membrane area. I just started. I highly appreciate your help

08 May 2021 0 0 View

i have some problem with chtMultiRegionSimpleFoam

--> FOAM FATAL ERROR: Maximum number of iterations exceeded From function Foam::scalar Foam::species::thermo::T(Foam::scalar, Foam::scalar, Foam::scalar, Foam::scalar (Foam::species::thermo::*)(Foam::scalar, Foam::scalar) const, Foam::scalar (Foam::species::thermo::*)(Foam::scalar, Foam::scalar) const, Foam::scalar (Foam::species::thermo::*)(Foam::scalar) const) const [with Thermo = Foam::hConstThermo >; Type = Foam::sensibleEnthalpy; Foam::scalar = double; Foam::species::thermo = Foam::species::thermo >, Foam::sensibleEnthalpy>] in file /home/ubuntu/OpenFOAM/OpenFOAM-4.1/src/thermophysicalModels/specie/lnInclude/thermoI.H at line 66. FOAM aborting #0 Foam::error::printStack(Foam::Ostream&) at ??:? #1 Foam::error::abort() at ??:? #2 Foam::heRhoThermo >, Foam::sensibleEnthalpy> > > >::calculate() at ??:? #3 Foam::heRhoThermo >, Foam::sensibleEnthalpy> > > >::correct() at ??:? #4 ? at ??:? #5 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #6 ? at ??:?

24 March 2021 0 0 View

Physics: Why do we describe light by referring to its wavelength, but microwaves and radar pulses by referring to their frequency?

In physics, the description of the properties of light generally refers to its wavelength (nm), while in the range of microwaves and radio waves we refer to the frequency of a signal (e.g. kHz or...

03 March 2021 1,682 3 View

What is the most Operating System (OS) which can be INSTALL on Tiny hard devices like Raspberry Pi (RPi) hardware ?

I'm targeting to deploy a mesh network and manually configure MANET routing protocols. I'm preparing scenarios, architectures, and hard devices needed to do that. Are there some step-by-step...

03 March 2021 1,931 5 View

Can we classify HV and LV lines based on line length?

I have dataset which shows the length of power lines. I need to classify the lines based on the line length. Is there a rule to classify the High voltage (HV) and low voltage (LV) lines based on...

03 March 2021 4,116 4 View

After a reference from Int J Body Compos Res, can any body help?

Hi, I am after the reference below, my library says it cannot obtain a copy either locally or internationally, any help appreciated! Chris Wang ZM, Heshka S, Wielopolski L, Pi-Sunyer FX, Pierson...

03 March 2021 6,193 1 View