Compton scattering

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Compton_scattering 

Compton scattering, discovered by Arthur Holly Compton, is the scattering of a high frequency photon after an interaction with a stationary charged particle, usually an electron. If it results in a decrease in energy (increase in wavelength) of the photon (which may be an X-ray or gamma ray photon), it is called the Compton effect. Part of the energy of the photon is transferred to the recoiling electron. Inverse Compton scattering occurs when a charged particle transfers part of its energy to a photon.

Introduction

Fig. 1: Schematic diagram of Compton's experiment. Compton scattering occurs in the graphite target on the left. The slit passes X-ray photons scattered at a selected angle. The energy of a scattered photon is measured using Bragg scattering in the crystal on the right in conjunction with ionization chamber; the chamber could measure total energy deposited over time, not the energy of single scattered photons.

Compton scattering is an example of inelastic scattering of light by a free charged particle, where the wavelength of the scattered light is different from that of the incident radiation. In Compton's original experiment (see Fig. 1), the energy of the X ray photon (≈17 keV) was very much larger than the binding energy of the atomic electron, so the electrons could be treated as being free after scattering. The amount by which the light's wavelength changes is called the Compton shift. Although nucleus Compton scattering exists, Compton scattering usually refers to the interaction involving only the electrons of an atom. The Compton effect was observed by Arthur Holly Compton in 1923 at Washington University in St. Louis and further verified by his graduate student Y. H. Woo in the years following. Compton earned the 1927 Nobel Prize in Physics for the discovery.

The effect is significant because it demonstrates that light cannot be explained purely as a wave phenomenon. Thomson scattering, the classical theory of an electromagnetic wave scattered by charged particles, cannot explain shifts in wavelength at low intensity: classically, light of sufficient intensity for the electric field to accelerate a charged particle to a relativistic speed will cause radiation-pressure recoil and an associated Doppler shift of the scattered light, but the effect would become arbitrarily small at sufficiently low light intensities regardless of wavelength. Thus, if we are to explain low-intensity Compton scattering, light must behave as if it consists of particles. Or the assumption that the electron can be treated as free is invalid resulting in the effectively infinite electron mass equal to the nuclear mass (see e.g. the comment below on elastic scattering of X-rays being from that effect). Compton's experiment convinced physicists that light can be treated as a stream of particle-like objects (quanta called photons), whose energy is proportional to the light wave's frequency.

As shown in Fig. 2, the interaction between an electron and a photon results in the electron being given part of the energy (making it recoil), and a photon of the remaining energy being emitted in a different direction from the original, so that the overall momentum of the system is also conserved. If the scattered photon still has enough energy, the process may be repeated. In this scenario, the electron is treated as free or loosely bound. Experimental verification of momentum conservation in individual Compton scattering processes by Bothe and Geiger as well as by Compton and Simon has been important in disproving the BKS theory.

Compton scattering is one of four competing processes when photons interact with matter. At energies of a few eV to a few keV, corresponding to visible light through soft X-rays, a photon can be completely absorbed and its energy can eject an electron from its host atom, a process known as the photoelectric effect. High-energy photons of 1.022 MeV and above may bombard the nucleus and cause an electron and a positron to be formed, a process called pair production; even-higher-energy photons (beyond a threshold energy of at least 1.670 MeV, depending on the nuclei involved), can eject a nucleon or alpha particle from the nucleus in a process called photodisintegration. Compton scattering is the most important interaction in the intervening energy region, at photon energies greater than those typical of the photoelectric effect but less than the pair-production threshold.

Description of the phenomenon

Fig. 2: A photon of wavelength ${\displaystyle \lambda }$ comes in from the left, collides with a target at rest, and a new photon of wavelength ${\displaystyle \lambda '}$ emerges at an angle ${\displaystyle \theta }$. The target recoils, carrying away an angle-dependent amount of the incident energy.

By the early 20th century, research into the interaction of X-rays with matter was well under way. It was observed that when X-rays of a known wavelength interact with atoms, the X-rays are scattered through an angle ${\displaystyle \theta }$ and emerge at a different wavelength related to ${\displaystyle \theta }$. Although classical electromagnetism predicted that the wavelength of scattered rays should be equal to the initial wavelength, multiple experiments had found that the wavelength of the scattered rays was longer (corresponding to lower energy) than the initial wavelength.

In 1923, Compton published a paper in the Physical Review that explained the X-ray shift by attributing particle-like momentum to light quanta (Einstein had proposed light quanta in 1905 in explaining the photo-electric effect, but Compton did not build on Einstein's work). The energy of light quanta depends only on the frequency of the light. In his paper, Compton derived the mathematical relationship between the shift in wavelength and the scattering angle of the X-rays by assuming that each scattered X-ray photon interacted with only one electron. His paper concludes by reporting on experiments which verified his derived relation:

$${\displaystyle \lambda '-\lambda ={\frac {h}{m_{e}c}}(1-\cos {\theta }),}$$

where

• ${\displaystyle \lambda }$ is the initial wavelength,
• ${\displaystyle \lambda '}$ is the wavelength after scattering,
• ${\displaystyle h}$ is the Planck constant,
• ${\displaystyle m_{e}}$ is the electron rest mass,
• ${\displaystyle c}$ is the speed of light, and
• ${\displaystyle \theta }$ is the scattering angle.

The quantity h/m_ec is known as the Compton wavelength of the electron; it is equal to 2.43×10⁻¹² m. The wavelength shift λ′ − λ is at least zero (for θ = 0°) and at most twice the Compton wavelength of the electron (for θ = 180°).

Compton found that some X-rays experienced no wavelength shift despite being scattered through large angles; in each of these cases the photon failed to eject an electron. Thus the magnitude of the shift is related not to the Compton wavelength of the electron, but to the Compton wavelength of the entire atom, which can be upwards of 10000 times smaller. This is known as "coherent" scattering off the entire atom since the atom remains intact, gaining no internal excitation.

In Compton's original experiments the wavelength shift given above was the directly-measurable observable. In modern experiments it is conventional to measure the energies, not the wavelengths, of the scattered photons. For a given incident energy ${\displaystyle E_{\gamma }=hc/\lambda }$, the outgoing final-state photon energy, ${\displaystyle E_{\gamma ^{\prime }}}$, is given by

$${\displaystyle E_{\gamma ^{\prime }}={\frac {E_{\gamma }}{1+(E_{\gamma }/m_{e}c^{2})(1-\cos \theta )}}.}$$

Derivation of the scattering formula

Fig. 3: Energies of a photon at 500 keV and an electron after Compton scattering.

A photon γ with wavelength λ collides with an electron e in an atom, which is treated as being at rest. The collision causes the electron to recoil, and a new photon γ' with wavelength λ' emerges at angle θ from the photon's incoming path. Let e' denote the electron after the collision. Compton allowed for the possibility that the interaction would sometimes accelerate the electron to speeds sufficiently close to the velocity of light as to require the application of Einstein's special relativity theory to properly describe its energy and momentum.

At the conclusion of Compton's 1923 paper, he reported results of experiments confirming the predictions of his scattering formula, thus supporting the assumption that photons carry momentum as well as quantized energy. At the start of his derivation, he had postulated an expression for the momentum of a photon from equating Einstein's already established mass-energy relationship of ${\displaystyle E=mc^{2}}$ to the quantized photon energies of ${\displaystyle hf}$, which Einstein had separately postulated. If ${\displaystyle mc^{2}=hf}$, the equivalent photon mass must be ${\displaystyle hf/c^{2}}$. The photon's momentum is then simply this effective mass times the photon's frame-invariant velocity c. For a photon, its momentum ${\displaystyle p=hf/c}$, and thus hf can be substituted for pc for all photon momentum terms which arise in course of the derivation below. The derivation which appears in Compton's paper is more terse, but follows the same logic in the same sequence as the following derivation.

The conservation of energy ${\displaystyle E}$ merely equates the sum of energies before and after scattering.

${\displaystyle E_{\gamma }+E_{e}=E_{\gamma '}+E_{e'}.}$

Compton postulated that photons carry momentum; thus from the conservation of momentum, the momenta of the particles should be similarly related by

${\displaystyle \mathbf {p} _{\gamma }=\mathbf {p} _{\gamma '}+\mathbf {p} _{e'},}$

in which (${\displaystyle {p_{e}}}$) is omitted on the assumption it is effectively zero.

The photon energies are related to the frequencies by

${\displaystyle E_{\gamma }=hf}$

${\displaystyle E_{\gamma '}=hf'}$

where h is Planck's constant.

Before the scattering event, the electron is treated as sufficiently close to being at rest that its total energy consists entirely of the mass-energy equivalence of its (rest) mass ${\displaystyle m_{e}}$,

${\displaystyle E_{e}=m_{e}c^{2}.}$

After scattering, the possibility that the electron might be accelerated to a significant fraction of the speed of light, requires that its total energy be represented using the relativistic energy–momentum relation

${\displaystyle E_{e'}={\sqrt {(p_{e'}c)^{2}+(m_{e}c^{2})^{2}}}~.}$

Substituting these quantities into the expression for the conservation of energy gives

${\displaystyle hf+m_{e}c^{2}=hf'+{\sqrt {(p_{e'}c)^{2}+(m_{e}c^{2})^{2}}}.}$

This expression can be used to find the magnitude of the momentum of the scattered electron,

$${\displaystyle p_{e'}^{\,2}c^{2}=(hf-hf'+m_{e}c^{2})^{2}-m_{e}^{2}c^{4}.}$$

(1)

Note that this magnitude of the momentum gained by the electron (formerly zero) exceeds the energy/c lost by the photon,

${\displaystyle {\frac {1}{c}}{\sqrt {(hf-hf'+m_{e}c^{2})^{2}-m_{e}^{2}c^{4}}}>{\frac {hf-hf'}{c}}~.}$

Equation (1) relates the various energies associated with the collision. The electron's momentum change involves a relativistic change in the energy of the electron, so it is not simply related to the change in energy occurring in classical physics. The change of the magnitude of the momentum of the photon is not just related to the change of its energy; it also involves a change in direction.

Solving the conservation of momentum expression for the scattered electron's momentum gives

${\displaystyle \mathbf {p} _{e'}=\mathbf {p} _{\gamma }-\mathbf {p} _{\gamma '}.}$

Making use of the scalar product yields the square of its magnitude,

${\displaystyle {\begin{aligned}p_{e'}^{\,2}&=\mathbf {p} _{e'}\cdot \mathbf {p} _{e'}=(\mathbf {p} _{\gamma }-\mathbf {p} _{\gamma '})\cdot (\mathbf {p} _{\gamma }-\mathbf {p} _{\gamma '})\\&=p_{\gamma }^{\,2}+p_{\gamma '}^{\,2}-2p_{\gamma }\,p_{\gamma '}\cos \theta .\end{aligned}}}$

In anticipation of ${\displaystyle p_{\gamma }c}$ being replaced with ${\displaystyle hf}$, multiply both sides by ${\displaystyle c^{2}}$,

${\displaystyle p_{e'}^{\,2}c^{2}=p_{\gamma }^{\,2}c^{2}+p_{\gamma '}^{\,2}c^{2}-2c^{2}p_{\gamma }\,p_{\gamma '}\cos \theta .}$

After replacing the photon momentum terms with ${\displaystyle hf/c}$, we get a second expression for the magnitude of the momentum of the scattered electron,

$${\displaystyle p_{e'}^{\,2}c^{2}=(hf)^{2}+(hf')^{2}-2(hf)(hf')\cos {\theta }~.}$$

(2)

Equating the alternate expressions for this momentum gives

${\displaystyle (hf-hf'+m_{e}c^{2})^{2}-m_{e}^{\,2}c^{4}=\left(hf\right)^{2}+\left(hf'\right)^{2}-2h^{2}ff'\cos {\theta },}$

which, after evaluating the square and canceling and rearranging terms, further yields

${\displaystyle 2hfm_{e}c^{2}-2hf'm_{e}c^{2}=2h^{2}ff'\left(1-\cos \theta \right).}$

Dividing both sides by ${\displaystyle 2hff'm_{e}c}$ yields

${\displaystyle {\frac {c}{f'}}-{\frac {c}{f}}={\frac {h}{m_{e}c}}\left(1-\cos \theta \right).}$

Finally, since fλ = f ' λ' = c,

$${\displaystyle \lambda '-\lambda ={\frac {h}{m_{e}c}}(1-\cos {\theta })~.}$$

(3)

It can further be seen that the angle φ of the outgoing electron with the direction of the incoming photon is specified by

$${\displaystyle \cot \varphi =\left(1+{\frac {hf}{m_{e}c^{2}}}\right)\tan(\theta /2)~.}$$

(4)

Applications

Compton scattering

Compton scattering is of prime importance to radiobiology, as it is the most probable interaction of gamma rays and high energy X-rays with atoms in living beings and is applied in radiation therapy.

Compton scattering is an important effect in gamma spectroscopy which gives rise to the Compton edge, as it is possible for the gamma rays to scatter out of the detectors used. Compton suppression is used to detect stray scatter gamma rays to counteract this effect.

Magnetic Compton scattering

Magnetic Compton scattering is an extension of the previously mentioned technique which involves the magnetisation of a crystal sample hit with high energy, circularly polarised photons. By measuring the scattered photons' energy and reversing the magnetisation of the sample, two different Compton profiles are generated (one for spin up momenta and one for spin down momenta). Taking the difference between these two profiles gives the magnetic Compton profile (MCP), given by ${\displaystyle J_{\text{mag}}(\mathbf {p} _{z})}$ - a one-dimensional projection of the electron spin density.

$${\displaystyle J_{\text{mag}}(\mathbf {p} _{z})={\frac {1}{\mu }}\iint _{-\infty }^{\infty }(n_{\uparrow }(\mathbf {p} )-n_{\downarrow }(\mathbf {p} ))d\mathbf {p} _{x}d\mathbf {p} _{y}}$$

where ${\displaystyle \mu }$ is the number of spin-unpaired electrons in the system, ${\displaystyle n_{\uparrow }(\mathbf {p} )}$ and ${\displaystyle n_{\downarrow }(\mathbf {p} )}$ are the three-dimensional electron momentum distributions for the majority spin and minority spin electrons respectively.

Since this scattering process is incoherent (there is no phase relationship between the scattered photons), the MCP is representative of the bulk properties of the sample and is a probe of the ground state. This means that the MCP is ideal for comparison with theoretical techniques such as density functional theory. The area under the MCP is directly proportional to the spin moment of the system and so, when combined with total moment measurements methods (such as SQUID magnetometry), can be used to isolate both the spin and orbital contributions to the total moment of a system. The shape of the MCP also yields insight into the origin of the magnetism in the system.

Inverse Compton scattering

Inverse Compton scattering is important in astrophysics. In X-ray astronomy, the accretion disk surrounding a black hole is presumed to produce a thermal spectrum. The lower energy photons produced from this spectrum are scattered to higher energies by relativistic electrons in the surrounding corona. This is surmised to cause the power law component in the X-ray spectra (0.2–10 keV) of accreting black holes.

The effect is also observed when photons from the cosmic microwave background (CMB) move through the hot gas surrounding a galaxy cluster. The CMB photons are scattered to higher energies by the electrons in this gas, resulting in the Sunyaev–Zel'dovich effect. Observations of the Sunyaev–Zel'dovich effect provide a nearly redshift-independent means of detecting galaxy clusters.

Some synchrotron radiation facilities scatter laser light off the stored electron beam. This Compton backscattering produces high energy photons in the MeV to GeV range subsequently used for nuclear physics experiments.

Non-linear inverse Compton scattering

Non-linear inverse Compton scattering (NICS) is the scattering of multiple low-energy photons, given by an intense electromagnetic field, in a high-energy photon (X-ray or gamma ray) during the interaction with a charged particle, such as an electron. It is also called non-linear Compton scattering and multiphoton Compton scattering. It is the non-linear version of inverse Compton scattering in which the conditions for multiphoton absorption by the charged particle are reached due to a very intense electromagnetic field, for example the one produced by a laser.

Non-linear inverse Compton scattering is an interesting phenomenon for all applications requiring high-energy photons since NICS is capable of producing photons with energy comparable to the charged particle rest energy and higher. As a consequence NICS photons can be used to trigger other phenomena such as pair production, Compton scattering, nuclear reactions, and can be used to probe non-linear quantum effects and non-linear QED.

Denaturation (biochemistry)

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Denaturation_(biochemistry) 

 

The effects of temperature on enzyme activity.
Top: increasing temperature increases the rate of reaction (Q10 coefficient).
Middle: the fraction of folded and functional enzyme decreases above its denaturation temperature.
Bottom: consequently, an enzyme's optimal rate of reaction is at an intermediate temperature.

 

IUPAC definition

Process of partial or total alteration of the native secondary, and/or tertiary, and/or quaternary structures of proteins or nucleic acids resulting in a loss of bioactivity.

Note 1: Modified from the definition given in ref.

Note 2: Denaturation can occur when proteins and nucleic acids are subjected to elevated temperature or to extremes of pH, or to nonphysiological concentrations of salt, organic solvents, urea, or other chemical agents.

Note 3: An enzyme loses its catalytic activity when it is denaturized.

In biochemistry, denaturation is a process in which proteins or nucleic acids lose the quaternary structure, tertiary structure, and secondary structure which is present in their native state, by application of some external stress or compound such as a strong acid or base, a concentrated inorganic salt, an organic solvent (e.g., alcohol or chloroform), agitation and radiation or heat. If proteins in a living cell are denatured, this results in disruption of cell activity and possibly cell death. Protein denaturation is also a consequence of cell death. Denatured proteins can exhibit a wide range of characteristics, from conformational change and loss of solubility to aggregation due to the exposure of hydrophobic groups. The loss of solubility as a result of denaturation is called coagulation. Denatured proteins lose their 3D structure and therefore cannot function.

Protein folding is key to whether a globular or membrane protein can do its job correctly; it must be folded into the right shape to function. However, hydrogen bonds, which play a big part in folding, are rather weak and thus easily affected by heat, acidity, varying salt concentrations, and other stressors which can denature the protein. This is one reason why homeostasis is physiologically necessary in many life forms.

This concept is unrelated to denatured alcohol, which is alcohol that has been mixed with additives to make it unsuitable for human consumption.

Common examples

(Top) The protein albumin in the egg white undergoes denaturation and loss of solubility when the egg is cooked. (Bottom) Paperclips provide a visual analogy to help with the conceptualization of the denaturation process.

When food is cooked, some of its proteins become denatured. This is why boiled eggs become hard and cooked meat becomes firm.

A classic example of denaturing in proteins comes from egg whites, which are typically largely egg albumins in water. Fresh from the eggs, egg whites are transparent and liquid. Cooking the thermally unstable whites turns them opaque, forming an interconnected solid mass. The same transformation can be effected with a denaturing chemical. Pouring egg whites into a beaker of acetone will also turn egg whites translucent and solid. The skin that forms on curdled milk is another common example of denatured protein. The cold appetizer known as ceviche is prepared by chemically "cooking" raw fish and shellfish in an acidic citrus marinade, without heat.

Protein denaturation

Denatured proteins can exhibit a wide range of characteristics, from loss of solubility to protein aggregation.

Functional proteins have four levels of structural organization:

1. Primary structure: the linear structure of amino acids in the polypeptide chain
2. Secondary structure: hydrogen bonds between peptide group chains in an alpha helix or beta sheet
3. Tertiary structure: three-dimensional structure of alpha helixes and beta helixes folded
4. Quaternary structure: three-dimensional structure of multiple polypeptides and how they fit together

Process of denaturation:

1. Functional protein showing a quaternary structure
2. When heat is applied it alters the intramolecular bonds of the protein
3. Unfolding of the polypeptides (amino acids)

Background

Proteins or polypeptides are polymers of amino acids. A protein is created by ribosomes that "read" RNA that is encoded by codons in the gene and assemble the requisite amino acid combination from the genetic instruction, in a process known as translation. The newly created protein strand then undergoes posttranslational modification, in which additional atoms or molecules are added, for example copper, zinc, or iron. Once this post-translational modification process has been completed, the protein begins to fold (sometimes spontaneously and sometimes with enzymatic assistance), curling up on itself so that hydrophobic elements of the protein are buried deep inside the structure and hydrophilic elements end up on the outside. The final shape of a protein determines how it interacts with its environment.

Protein folding consists of a balance between a substantial amount of weak intra-molecular interactions within a protein (Hydrophobic, electrostatic, and Van Der Waals Interactions) and protein-solvent interactions. As a result, this process is heavily reliant on environmental state that the protein resides in. These environmental conditions include, and are not limited to, temperature, salinity, pressure, and the solvents that happen to be involved. Consequently, any exposure to extreme stresses (e.g. heat or radiation, high inorganic salt concentrations, strong acids and bases) can disrupt a protein's interaction and inevitably lead to denaturation.

When a protein is denatured, secondary and tertiary structures are altered but the peptide bonds of the primary structure between the amino acids are left intact. Since all structural levels of the protein determine its function, the protein can no longer perform its function once it has been denatured. This is in contrast to intrinsically unstructured proteins, which are unfolded in their native state, but still functionally active and tend to fold upon binding to their biological target.

How denaturation occurs at levels of protein structure

See also: Protein structure

• In quaternary structure denaturation, protein sub-units are dissociated and/or the spatial arrangement of protein subunits is disrupted.
• Tertiary structure denaturation involves the disruption of:
  • Covalent interactions between amino acid side-chains (such as disulfide bridges between cysteine groups)
  • Non-covalent dipole-dipole interactions between polar amino acid side-chains (and the surrounding solvent)
  • Van der Waals (induced dipole) interactions between nonpolar amino acid side-chains.
• In secondary structure denaturation, proteins lose all regular repeating patterns such as alpha-helices and beta-pleated sheets, and adopt a random coil configuration.
• Primary structure, such as the sequence of amino acids held together by covalent peptide bonds, is not disrupted by denaturation.

Loss of function

Most biological substrates lose their biological function when denatured. For example, enzymes lose their activity, because the substrates can no longer bind to the active site, and because amino acid residues involved in stabilizing substrates' transition states are no longer positioned to be able to do so. The denaturing process and the associated loss of activity can be measured using techniques such as dual-polarization interferometry, CD, QCM-D and MP-SPR.

Loss of activity due to heavy metals and metalloids

By targeting proteins, heavy metals have been known to disrupt the function and activity carried out by proteins. It is important to note that heavy metals fall into categories consisting of transition metals as well as a select amount of metalloid. These metals, when interacting with native, folded proteins, tend to play a role in obstructing their biological activity. This interference can be carried out in a different number of ways. These heavy metals can form a complex with the functional side chain groups present in a protein or form bonds to free thiols. Heavy metals also play a role in oxidizing amino acid side chains present in protein. Along with this, when interacting with metalloproteins, heavy metals can dislocate and replace key metal ions. As a result, heavy metals can interfere with folded proteins, which can strongly deter protein stability and activity.

Reversibility and irreversibility

In many cases, denaturation is reversible (the proteins can regain their native state when the denaturing influence is removed). This process can be called renaturation. This understanding has led to the notion that all the information needed for proteins to assume their native state was encoded in the primary structure of the protein, and hence in the DNA that codes for the protein, the so-called "Anfinsen's thermodynamic hypothesis".

Denaturation can also be irreversible. This irreversibility is typically a kinetic, not thermodynamic irreversibility, as a folded protein generally has lower free energy than when it is unfolded. Through kinetic irreversibility, the fact that the protein is stuck in a local minimum can stop it from ever refolding after it has been irreversibly denatured.

Protein denaturation due to pH

Denaturation can also be caused by changes in the pH which can affect the chemistry of the amino acids and their residues. The ionizable groups in amino acids are able to become ionized when changes in pH occur. A pH change to more acidic or more basic conditions can induce unfolding. Acid-induced unfolding often occurs between pH 2 and 5, base-induced unfolding usually requires pH 10 or higher.

Nucleic acid denaturation

Main article: Nucleic acid thermodynamics

Nucleic acids (including RNA and DNA) are nucleotide polymers synthesized by polymerase enzymes during either transcription or DNA replication. Following 5'-3' synthesis of the backbone, individual nitrogenous bases are capable of interacting with one another via hydrogen bonding, thus allowing for the formation of higher-order structures. Nucleic acid denaturation occurs when hydrogen bonding between nucleotides is disrupted, and results in the separation of previously annealed strands. For example, denaturation of DNA due to high temperatures results in the disruption of Watson and Crick base pairs and the separation of the double stranded helix into two single strands. Nucleic acid strands are capable of re-annealling when "normal" conditions are restored, but if restoration occurs too quickly, the nucleic acid strands may re-anneal imperfectly resulting in the improper pairing of bases.

Biologically-induced denaturation

DNA denaturation occurs when hydrogen bonds between Watson and Crick base pairs are disturbed.

The non-covalent interactions between antiparallel strands in DNA can be broken in order to "open" the double helix when biologically important mechanisms such as DNA replication, transcription, DNA repair or protein binding are set to occur. The area of partially separated DNA is known as the denaturation bubble, which can be more specifically defined as the opening of a DNA double helix through the coordinated separation of base pairs.

The first model that attempted to describe the thermodynamics of the denaturation bubble was introduced in 1966 and called the Poland-Scheraga Model. This model describes the denaturation of DNA strands as a function of temperature. As the temperature increases, the hydrogen bonds between the Watson and Crick base pairs are increasingly disturbed and "denatured loops" begin to form. However, the Poland-Scheraga Model is now considered elementary because it fails to account for the confounding implications of DNA sequence, chemical composition, stiffness and torsion.

Recent thermodynamic studies have inferred that the lifetime of a singular denaturation bubble ranges from 1 microsecond to 1 millisecond. This information is based on established timescales of DNA replication and transcription. Currently, biophysical and biochemical research studies are being performed to more fully elucidate the thermodynamic details of the denaturation bubble.

Denaturation due to chemical agents

Formamide denatures DNA by disrupting the hydrogen bonds between Watson and Crick base pairs. Orange, blue, green, and purple lines represent adenine, thymine, guanine, and cytosine respectively. The three short black lines between the bases and the formamide molecules represent newly formed hydrogen bonds.

With polymerase chain reaction (PCR) being among the most popular contexts in which DNA denaturation is desired, heating is the most frequent method of denaturation. Other than denaturation by heat, nucleic acids can undergo the denaturation process through various chemical agents such as formamide, guanidine, sodium salicylate, dimethyl sulfoxide (DMSO), propylene glycol, and urea. These chemical denaturing agents lower the melting temperature (T_m) by competing for hydrogen bond donors and acceptors with pre-existing nitrogenous base pairs. Some agents are even able to induce denaturation at room temperature. For example, alkaline agents (e.g. NaOH) have been shown to denature DNA by changing pH and removing hydrogen-bond contributing protons. These denaturants have been employed to make Denaturing Gradient Gel Electrophoresis gel (DGGE), which promotes denaturation of nucleic acids in order to eliminate the influence of nucleic acid shape on their electrophoretic mobility.

Chemical denaturation as an alternative

The optical activity (absorption and scattering of light) and hydrodynamic properties (translational diffusion, sedimentation coefficients, and rotational correlation times) of formamide denatured nucleic acids are similar to those of heat-denatured nucleic acids. Therefore, depending on the desired effect, chemically denaturing DNA can provide a gentler procedure for denaturing nucleic acids than denaturation induced by heat. Studies comparing different denaturation methods such as heating, beads mill of different bead sizes, probe sonication, and chemical denaturation show that chemical denaturation can provide quicker denaturation compared to the other physical denaturation methods described. Particularly in cases where rapid renaturation is desired, chemical denaturation agents can provide an ideal alternative to heating. For example, DNA strands denatured with alkaline agents such as NaOH renature as soon as phosphate buffer is added.

Denaturation due to air

Small, electronegative molecules such as nitrogen and oxygen, which are the primary gases in air, significantly impact the ability of surrounding molecules to participate in hydrogen bonding. These molecules compete with surrounding hydrogen bond acceptors for hydrogen bond donors, therefore acting as "hydrogen bond breakers" and weakening interactions between surrounding molecules in the environment. Antiparellel strands in DNA double helices are non-covalently bound by hydrogen bonding between Watson and Crick base pairs; nitrogen and oxygen therefore maintain the potential to weaken the integrity of DNA when exposed to air. As a result, DNA strands exposed to air require less force to separate and exemplify lower melting temperatures.

Applications

Many laboratory techniques rely on the ability of nucleic acid strands to separate. By understanding the properties of nucleic acid denaturation, the following methods were created:

• PCR
• Southern blot
• Northern blot
• DNA Sequencing

Denaturants

Protein denaturants

Acids

Acidic protein denaturants include:

• Acetic acid
• Trichloroacetic acid 12% in water
• Sulfosalicylic acid

Bases

Bases work similarly to acids in denaturation. They include:

• Sodium bicarbonate

Solvents

Most organic solvents are denaturing, including:

• Ethanol

Cross-linking reagents

Cross-linking agents for proteins include:

• Formaldehyde
• Glutaraldehyde

Chaotropic agents

Chaotropic agents include:

• Urea 6–8 mol/L
• Guanidinium chloride 6 mol/L
• Lithium perchlorate 4.5 mol/L
• Sodium dodecyl sulfate

Disulfide bond reducers

Agents that break disulfide bonds by reduction include:

• 2-Mercaptoethanol
• Dithiothreitol
• TCEP (tris(2-carboxyethyl)phosphine)

Chemically reactive agents

Agents such as hydrogen peroxide, elemental chlorine, hypochlorous acid (chlorine water), bromine, bromine water, iodine, nitric and oxidising acids, and ozone react with sensitive moieties such as sulfide/thiol, activated aromatic rings (phenylalanine) in effect damage the protein and render it useless.

Other

• Mechanical agitation
• Picric acid
• Radiation
• Temperature

Nucleic acid denaturants

Chemical

Acidic nucleic acid denaturants include:

• Acetic acid
• HCl
• Nitric acid

Basic nucleic acid denaturants include:

• NaOH

Other nucleic acid denaturants include:

• DMSO
• Formamide
• Guanidine
• Sodium salicylate
• Propylene glycol
• Urea

Physical

• Thermal denaturation
• Beads mill
• Probe sonication
• Radiation

New religious movement

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/New_religious_movement 

A member of the International Society for Krishna Consciousness proselytising on the streets of Moscow, Russia

A new religious movement (NRM), also known as alternative spirituality or a new religion, is a religious or spiritual group that has modern origins and is peripheral to its society's dominant religious culture. NRMs can be novel in origin or they can be part of a wider religion, in which case they are distinct from pre-existing denominations. Some NRMs deal with the challenges which the modernizing world poses to them by embracing individualism, while other NRMs deal with them by embracing tightly knit collective means. Scholars have estimated that NRMs number in the tens of thousands worldwide, with most of their members living in Asia and Africa. Most NRMs only have a few members, some of them have thousands of members, and a few of them have more than a million members.

There is no single, agreed-upon criterion for defining a "new religious movement". There is debate as to how the term "new" should be interpreted in this context. One perspective is that it should designate a religion that is more recent in its origins than large, well-established religions like Christianity, Judaism, Islam, Hinduism and Buddhism. An alternate perspective is that "new" should mean that a religion is more recent in its formation. Some scholars view the 1950s or the end of the Second World War in 1945 as the defining time, while others look as far back as from the middle of the 19th century or the founding of the Latter Day Saint movement in 1830 and Tenrikyo in 1838.

New religions have typically faced opposition from established religious organisations and secular institutions. In Western nations, a secular anti-cult movement and a Christian countercult movement emerged during the 1970s and 1980s to oppose emergent groups. In the 1970s, the distinct field of new religions studies developed within the academic study of religion. There are several scholarly organisations and peer-reviewed journals devoted to the subject. Religious studies scholars contextualize the rise of NRMs in modernity as a product of, and answer to modern processes of secularization, globalization, detraditionalization, fragmentation, reflexivity, and individualization.

History

1893 Parliament of the World's Religions

In 1830 the Latter Day Saint movement was founded by Joseph Smith. It is one of the largest new religious movements in terms of membership. In Japan, 1838 marks the beginning of Tenrikyo. In 1844 Bábism was established in Iran, from which the Baháʼí Faith was founded by Bahá'u'lláh in 1863. In 1860 Donghak, later Cheondoism, was founded by Choi Jae-Woo in Korea. It later ignited the Donghak Peasant Revolution in 1894. In 1889, Ahmadiyya, an Islamic branch, was founded by Mirza Ghulam Ahmad. In 1891, the Unity Church, the first New Thought denomination, was founded in the United States.

In 1893, the first Parliament of the World's Religions was held in Chicago. The conference included NRMs of the time such as spiritualism, Baháʼí Faith, and Christian Science. Henry Harris Jessup, who addressed the meeting, was the first to mention the Baháʼí Faith in the United States. Also attending were Soyen Shaku, the "First American Ancestor" of Zen, the Theravāda Buddhist preacher Anagarika Dharmapala, and the Jain preacher Virchand Gandhi. This conference gave Asian religious teachers their first wide American audience.

In 1911, the Nazareth Baptist Church, the first and one of the largest modern African initiated churches, was founded by Isaiah Shembe in South Africa. The early 20th century also saw a rise in interest in Asatru. The 1930s saw the rise of the Nation of Islam and the Jehovah's Witnesses in the United States; the rise of the Rastafari movement in Jamaica; the rise of Cao Đài and Hòa Hảo in Vietnam; the rise of Soka Gakkai in Japan; and the rise Zailiism and Yiguandao in China. In the 1940s, Gerald Gardner began to outline the modern pagan religion of Wicca.

New religious movements expanded in many nations in the 1950s and 1960s. Japanese new religions became very popular after the Shinto Directive (1945) forced the Japanese government to separate itself from Shinto, which had been the state religion of Japan, bringing about greater freedom of religion. In 1954 Scientology was founded in the United States and the Unification Church was founded in South Korea. In 1955 the Aetherius Society was founded in England. It and some other NRMs, have been called UFO religions because they combine the belief in extraterrestrial life with traditional religious principles. In 1965, Paul Twitchell founded Eckankar, an NRM derived partially from Sant Mat. In 1966 the International Society for Krishna Consciousness was founded in the United States by A.C. Bhaktivedanta Swami Prabhupada and Anton LaVey founded the Church of Satan. In 1967, The Beatles' visit to Maharishi Mahesh Yogi in India brought public attention to the Transcendental Meditation movement.

Practitioners of Falun Gong perform spiritual exercises in Guangzhou, China.

In the late 1980s and 1990s, the decline of communism and the revolutions of 1989 opened up new opportunities for NRMs. Falun Gong was first taught publicly in Northeast China in 1992 by Li Hongzhi. At first it was accepted by the Chinese government and by 1999 there were 70 million practitioners in China, but in July 1999 the government started to view the movement as a threat and began attempts to eradicate it.

In the 21st century, many NRMs are using the Internet to give out information, to recruit members, and sometimes to hold online meetings and rituals. That is sometimes referred to as cybersectarianism. Sabina Magliocco, professor of Anthropology and Folklore at California State University, Northridge, has discussed the growing popularity of new religious movements on the Internet.

In 2006 J. Gordon Melton, executive director of the Institute for the Study of American Religions at the University of California, Santa Barbara, told The New York Times that 40 to 45 new religious movements emerge each year in the United States. In 2007, religious scholar Elijah Siegler said that, though no NRM had become the dominant faith in any country, many of the concepts they first introduced (often referred to as "New Age" ideas) have become part of worldwide mainstream culture.

Beliefs and practices

A Rasta man wearing symbols of his religious identity in Barbados

As noted by Barker, NRMs should not be "lumped together". They differ from one another on many issues. Virtually no generalisation can be made about NRMs that applies to every group, with Barrett noting that "generalizations tend not to be very helpful" when studying NRMs. Melton expressed the view that there is "no single characteristic or set of characteristics" that all new religions share, "not even their newness." Bryan Wilson wrote, "Chief among the miss-directed assertions has been the tendency to speak of new religious movements as if they differed very little if at all, one from another. The tendency has been to lump them altogether and indiscriminately to attribute to all of the characteristics which are, in fact, valid for only one or two." NRMs themselves often claim that they exist at a crucial place in time and space.

Scriptures

Some NRMs venerate unique scriptures, while others reinterpret existing texts, utilizing a range of older elements. They frequently claim that these are not new, but rather had been forgotten truths that are being revived. NRM scriptures often incorporate modern scientific knowledge, sometimes with the claim that they are bringing unity to science and religion. Some NRMs believe that their scriptures are received through mediums. The Urantia Book, the core scripture of the Urantia Movement, was published in 1955 and is said to be the product of a continuous process of revelation from "celestial beings" which began in 1911. Some NRMs, particularly those that are forms of occultism, have a prescribed system of courses and grades through which members can progress.

Celibacy

Some NRMs promote celibacy, the state of voluntarily being unmarried, sexually abstinent, or both. Some, including the Shakers and more recent NRMs, inspired by Hindu traditions, see it as a lifelong commitment. Others, including the Unification Church, as a stage in spiritual development. In some Buddhist NRMs, celibacy is practiced mostly by older women who become nuns. Some people join NRMs and practice celibacy as a rite of passage in order to move beyond previous sexual problems or bad experiences. Groups that promote celibacy require a strong recruitment drive to survive; the Shakers established orphanages to bring new individuals into their community.

Violence

Violent incidents involving NRMs are very rare. In events having a large number of casualties, the new religion was led by a charismatic leader. Beginning in 1978 the deaths of 913 members of the Peoples Temple in Jonestown, Guyana by both murder and suicide brought an image of "killer cults" to public attention. Several subsequent events contributed to the concept. In 1994, members of the Order of the Solar Temple committed suicide in Canada and Switzerland. In 1995 members of the Japanese new religion Aum Shinrikyo murdered a number of people during a sarin attack on the Tokyo subway. In 1997, 39 members of the Heaven's Gate group committed suicide in the belief that their spirits would leave the Earth and join a passing comet. There have also been cases in which members of NRMs have been killed after they engaged in dangerous actions due to mistaken belief in their own invincibility. For example, in Uganda, several hundred members of the Holy Spirit Movement were killed as they approached gunfire because its leader, Alice Lakwena, told them that they would be protected from bullets by the oil of the shea tree.

Leadership and succession

Mary Baker Eddy

NRMs are typically founded and led by a charismatic leader. The death of any religion's founder represents a significant moment in its history. Over the months and years following its leader's death, the movement can die out, fragment into multiple groups, consolidate its position, or change its nature to become something quite different than what its founder intended. In some cases, an NRM moves closer to the religious mainstream after the death of its founder.

A number of founders of new religions established plans for succession to prevent confusion after their deaths. Mary Baker Eddy, the American founder of Christian Science, spent fifteen years working on her book The Manual of the Mother Church, which laid out how the group should be run by her successors. The leadership of the Baháʼí Faith passed through a succession of individuals until 1963, when it was assumed by the Universal House of Justice, members of which are elected by the worldwide congregation. A.C. Bhaktivedanta Swami Prabhupada, the founder of the International Society for Krishna Consciousness, appointed 11 "Western Gurus" to act as initiating gurus and to continue to direct the organisation. However, according to British scholar of religion Gavin Flood, "many problems followed from their appointment and the movement has since veered away from investing absolute authority in a few, fallible, human teachers.”

Membership

Demographics

NRMs typically consist largely of first-generation believers, and thus often have a younger average membership than mainstream religious congregations. Some NRMs have been formed by groups who have split from a pre-existing religious group. As these members grow older, many have children who are then brought up within the NRM.

In the Third World, NRMs most often appeal to the poor and oppressed sectors of society. Within Western countries, they are more likely to appeal to members of the middle and upper-middle classes, with Barrett stating that new religions in the UK and US largely attract "white, middle-class late teens and twenties." There are exceptions, such as the Rastafari movement and the Nation of Islam, which have primarily attracted disadvantaged black youth in Western countries.

A popular conception, unsupported by evidence, holds that those who convert to new religions are either mentally ill or become so through their involvement with them. Dick Anthony, a forensic psychologist noted for his writings on the brainwashing controversy, has defended NRMs, and in 1988 argued that involvement in such movements may often be beneficial: "There's a large research literature published in mainstream journals on the mental health effects of new religions. For the most part, the effects seem to be positive in any way that's measurable."

Joining

Those who convert to an NRM typically believe that in doing so they are gaining some benefit in their life. This can come in many forms, from an increasing sense of freedom to a release from drug dependency, and a feeling of self-respect and direction. Many of those who have left NRMs report that they have gained from their experience. There are various reasons as to why an individual would join and then remain part of an NRM, including both push and pull factors. According to Marc Galanter, professor of psychiatry at NYU, typical reasons why people join NRMs include a search for community and a spiritual quest. Sociologists Stark and Bainbridge, in discussing the process by which people join new religious groups, have questioned the utility of the concept of conversion, suggesting that affiliation is a more useful concept.

A popular explanation for why people join new religious movements is that they have been "brainwashed" or subject to "mind control" by the NRM itself. This explanation provides a rationale for "deprogramming", a process in which members of NRMs are illegally kidnapped by individuals who then attempt to convince them to reject their beliefs. Professional deprogrammers, therefore, have a financial interest in promoting the "brainwashing" explanation. Academic research, however, has demonstrated that these brainwashing techniques "simply do not exist".

Leaving

Many members of NRMs leave these groups of their own free will. Some of those who do so retain friends within the movement. Some of those who leave a religious community are unhappy with the time that they spent as part of it. Leaving a NRM can pose a number of difficulties. It may result in their having to abandon a daily framework that they had previously adhered to. It may also generate mixed emotions as ex-members lose the feelings of absolute certainty that they had held while in the group.

Reception

Academic scholarship

Main article: Academic study of new religious movements

Three basic questions have been paramount in orienting theory and research on NRMs: what are the identifying markers of NRMs that distinguish them from other types of religious groups?; what are the different types of NRMs and how do these different types relate to the established institutional order of the host society?; and what are the most important ways that NRMs respond to the sociocultural dislocation that leads to their formation?

— Sociologist of religion David G. Bromley

The academic study of new religious movements is known as 'new religions studies' (NRS). The study draws from the disciplines of anthropology, psychiatry, history, psychology, sociology, religious studies, and theology. Barker noted that there are five sources of information on NRMs: the information provided by such groups themselves, that provided by ex-members as well as the friends and relatives of members, organisations that collect information on NRMs, the mainstream media, and academics studying such phenomena.

The study of new religions is unified by its topic of interest, rather than by its methodology, and is therefore interdisciplinary in nature. A sizeable body of scholarly literature on new religions has been published, most of it produced by social scientists. Among the disciplines that NRS utilises are anthropology, history, psychology, religious studies, and sociology. Of these approaches, sociology played a particularly prominent role in the development of the field, resulting in it being initially confined largely to a narrow array of sociological questions. This came to change in later scholarship, which began to apply theories and methods initially developed for examining more mainstream religions to the study of new ones.

Most research has been directed toward those new religions that attract public controversy. Less controversial NRMs tend to be the subject of less scholarly research. It has also been noted that scholars of new religions often avoid researching certain movements that scholars from other backgrounds study. The feminist spirituality movement is usually examined by scholars of women's studies, African-American new religions by scholars of Africana studies, and Native American new religions by scholars of Native American studies.

Definitions and terminology

A Rainbow Gathering in Bosnia, 2007

J. Gordon Melton argued that "new religious movements" should be defined by the way dominant religious and secular forces within a given society treat them. According to him, NRMs constituted "those religious groups that have been found, from the perspective of the dominant religious community (and in the West that is almost always a form of Christianity), to be not just different, but unacceptably different." Barker cautioned against Melton's approach, arguing that negating the "newness" of "new religious movements" raises problems, for it is "the very fact that NRMs are new that explains many of the key characteristics they display".

George Chryssides favors "simple" definition, for him, NRM is an organization founded within the past 150 or so years, which cannot be easily classified within one of the world's main religious traditions.

Scholars of religion Olav Hammer and Mikael Rothstein argued that "new religions are just young religions" and as a result, they are "not inherently different" from mainstream and established religious movements, with the differences between the two having been greatly exaggerated by the media and popular perceptions. Melton has stated that those NRMs that "were offshoots of older religious groups... tended to resemble their parent groups far more than they resembled each other." One question that faces scholars of religion is when a new religious movement ceases to be "new." As noted by Barker, "In the first century, Christianity was new, in the seventh century Islam was new, in the eighteenth century Methodism was new, in the nineteenth century the Seventh-day Adventists, Christadelphians, and Jehovah's Witnesses were new; in the twenty-first century the Unification Church, the ISKCON, and Scientology are beginning to look old."

Some NRMs are strongly counter-cultural and 'alternative' in the society where they appear, while others are far more similar to a society's established traditional religions. Generally, Christian denominations are not seen as new religious movements; nevertheless, The Church of Jesus Christ of Latter-day Saints, the Jehovah's Witnesses, Christian Science, and the Shakers have been studied as NRMs. The same situation with Jewish religious movements, when Reform Judaism and newer divisions have been named among NRM.

There are also problems in the use of "religion" within the term "new religious movements". This is because various groups, particularly active within the New Age milieu, have many traits in common with different NRMs but emphasise personal development and humanistic psychology, and are not clearly "religious" in nature.

Since at least the early 2000s, most sociologists of religion have used the term "new religious movement" in order to avoid the pejorative undertones of terms like "cult" and "sect". These are words that have been used in different ways by different groups. For instance, from the nineteenth century onward a number of sociologists used the terms "cult" and "sect" in very specific ways. The sociologist Ernst Troeltsch for instance differentiated "churches" from "sect" by claiming that the former term should apply to groups that stretch across social strata while "sects" typically contain converts from socially disadvantaged sectors of society.

The term "cult" is used in reference to devotion or dedication to a particular person or place. For instance, within the Roman Catholic Church devotion to Mary, mother of Jesus is usually termed the "Cult of Mary". It is also used in non-religious contexts to refer to fandoms devoted to television shows like The Prisoner, The X-Files, and Buffy the Vampire Slayer. In the United States, people began to use "cult" in a pejorative manner, to refer to Spiritualism and Christian Science during the 1890s. As commonly used, for instance in sensationalist tabloid articles, the term "cult" continues to have pejorative associations.

The term "new religions" is a calque of shinshūkyō (新宗教), a Japanese term developed to describe the proliferation of Japanese new religions in the years following the Second World War. From Japan this term was translated and used by several American authors, including Jacob Needleman, to describe the range of groups that appeared in the San Francisco Bay Area during the 1960s. This term, amongst others, was adopted by Western scholars as an alternative to "cult". However, "new religious movements" has failed to gain widespread public usage in the manner that "cult" has. Other terms that have been employed for many NRMs are "alternative religion" and "alternative spirituality", something used to convey the difference between these groups and established or mainstream religious movements while at the same time evading the problem posed by groups that are not particularly new.

The 1970s was the era of the so-called "cult wars," led by "cult-watching groups." The efforts of the anti-cult movement condensed a moral panic around the concept of cults. Public fears around Satanism, in particular, came to be known as a distinct phenomenon, the "Satanic Panic." Consequently, scholars such as Eileen Barker, James T. Richardson, Timothy Miller and Catherine Wessinger argued that the term "cult" had become too laden with negative connotations, and "advocated dropping its use in academia." A number of alternatives to the term "new religious movement" are used by some scholars. These include "alternative religious movements" (Miller), "emergent religions" (Ellwood) and "marginal religious movements" (Harper and Le Beau).

Opposition

Main article: Cult

There has been opposition to NRMs throughout their history. Some historical events have been: Anti-Mormonism, the persecution of Jehovah's Witnesses, the persecution of Baháʼís, and the persecution of Falun Gong. There are also instances in which violence has been directed at new religions. In the United States the founder of the Latter Day Saint movement, Joseph Smith, was killed by a lynch mob in 1844. In India there have been mob killings of members of the Ananda Marga group. Such violence can also be administered by the state. In Iran, followers of the Baháʼí Faith have faced persecution, while the Ahmadiyya have faced similar violence in Pakistan. Since 1999, the persecution of Falun Gong in China has been severe. Ethan Gutmann interviewed over 100 witnesses and estimated that 65,000 Falun Gong practitioners were killed for their organs from 2000 to 2008.

Christian countercult movement

Main article: Christian countercult movement

In the 1930s, Christian critics of NRMs began referring to them as "cults". The 1938 book The Chaos of Cults by Jan Karel van Baalen (1890–1968), an ordained minister in the Christian Reformed Church in North America, was especially influential. In the US, the Christian Research Institute was founded in 1960 by Walter Martin to counter opposition to evangelical Christianity and has come to focus on criticisms of NRMs. Presently the Christian countercult movement opposes most NRMs because of theological differences. It is closely associated with evangelical Christianity. The UK-based Reachout Trust was initially established to oppose the Jehovah's Witnesses and what it regarded as "counterfeit Christian groups", but it came to wider attention in the late 1980s and 1990s for its role in promoting claims about Satanic ritual abuse.

Anti-cult movement

Main article: Anti-cult movement

The 1960s and 1970s saw the emergence of a number of highly visible new religious movements... [These] seemed so outlandish that many people saw them as evil cults, fraudulent organizations or scams that recruited unaware people by means of mind-control techniques. Real or serious religions, it was felt, should appear in recognizable institutionalized forms, be suitably ancient, and – above all – advocate relatively familiar theological notions and modes of conduct. Most new religions failed to comply with such standards.

— Religious studies scholars Olav Hammer and Mikael Rothstein

In the 1970s and 1980s some NRMs, as well as some non-religious groups, came under opposition by the newly organized anti-cult movement, which mainly charged them with psychological abuse of their own members. It actively seeks to discourage people from joining new religions (which it refers to as "cults"). It also encourages members of these groups to leave them, and at times seeking to restrict their freedom of movement.

Family members are often distressed when a relative of theirs joins a new religion. Although children break away from their parents for all manner of reasons, in cases where NRMS are involved it is often the latter that are blamed for the break. Some anti-cultist groups emphasise the idea that "cults" always use deceit and trickery to recruit members. The anti-cult movement adopted the term brainwashing, which had been developed by the journalist Edward Hunter and then used by Robert J. Lifton to apply to the methods employed by Chinese to convert captured US soldiers to their cause in the Korean War. Lifton himself had doubts about the applicability of his 'brainwashing' hypothesis to the techniques used by NRMs to convert recruits. A number of ex-members of various new religions have made false allegations about their experiences in such groups. For instance, in the late 1980s a man in Dublin, Ireland was given a three-year suspended sentence for falsely claiming that he had been drugged, kidnapped, and held captive by members of ISKCON.

Scholars of religion have often critiqued anti-cult groups of un-critically believing anecdotal stories provided by the ex-members of new religions, of encouraging ex-members to think that they are the victims of manipulation and abuse, and of irresponsibly scare-mongering about NRMs. Of the "well over a thousand groups that have been or might be called cults" listed in the files of INFORM, says Eileen Barker, the "vast majority" have not engaged in criminal activities.

Popular culture and news media

Main article: New religious movements and cults in popular culture

New religious movements and cults have appeared as themes or subjects in literature and popular culture, while notable representatives of such groups have produced a large body of literary works. Beginning in the 1700s authors in the English-speaking world began introducing members of "cults" as antagonists. In the twentieth century, concern for the rights and feelings of religious minorities led authors to most often invent fictional cults for their villains to be members of. Fictional cults continue to be popular in film, television, and gaming in the same way, while some popular works treat new religious movements in a serious manner.

An article on the categorization of new religious movements in US print media published by The Association for the Sociology of Religion (formerly the American Catholic Sociological Society), criticizes the print media for failing to recognize social-scientific efforts in the area of new religious movements, and its tendency to use popular or anti-cultist definitions rather than social-scientific insight, and asserts that "The failure of the print media to recognize social-scientific efforts in the area of religious movement organizations impels us to add yet another failing mark to the media report card Weiss (1985) has constructed to assess the media's reporting of the social sciences."