Endocrine system

From Wikipedia, the free encyclopedia

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

 

Endocrine system
Main glands of the human endocrine system

The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant organs. In vertebrates, the hypothalamus is the neural control center for all endocrine systems.

In humans, the major endocrine glands are the thyroid, parathyroid, pituitary, pineal, and adrenal glands, and the (male) testis and (female) ovaries. The hypothalamus, pancreas, and thymus also function as endocrine glands, among other functions. (The hypothalamus and pituitary glands are organs of the neuroendocrine system. One of the most important functions of the hypothalamus—it is located in the brain adjacent to the pituitary gland—is to link the endocrine system to the nervous system via the pituitary gland.) Other organs, such as the kidneys, also have roles within the endocrine system by secreting certain hormones. The study of the endocrine system and its disorders is known as endocrinology. The thyroid secretes thyroxine, the pituitary secretes growth hormone, the pineal secretes melatonin, the testis secretes testosterone, and the ovaries secrete estrogen and progesterone.

Glands that signal each other in sequence are often referred to as an axis, such as the hypothalamic–pituitary–adrenal axis. In addition to the specialized endocrine organs mentioned above, many other organs that are part of other body systems have secondary endocrine functions, including bone, kidneys, liver, heart and gonads. For example, the kidney secretes the endocrine hormone erythropoietin. Hormones can be amino acid complexes, steroids, eicosanoids, leukotrienes, or prostaglandins.

The endocrine system is contrasted both to exocrine glands, which secrete hormones to the outside of the body, and to the system known as paracrine signalling between cells over a relatively short distance. Endocrine glands have no ducts, are vascular, and commonly have intracellular vacuoles or granules that store their hormones. In contrast, exocrine glands, such as salivary glands, mammary glands, and submucosal glands within the gastrointestinal tract, tend to be much less vascular and have ducts or a hollow lumen. Endocrinology is a branch of internal medicine.

Structure

Major endocrine systems

The human endocrine system consists of several systems that operate via feedback loops. Several important feedback systems are mediated via the hypothalamus and pituitary.

• TRH – TSH – T3/T4
• GnRH – LH/FSH – sex hormones
• CRH – ACTH – cortisol
• Renin – angiotensin – aldosterone
• Leptin vs. ghrelin

Glands

Main article: Endocrine gland

Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into interstitial spaces where they are absorbed into blood rather than through a duct. The major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus and adrenal glands. The hypothalamus and pituitary gland are neuroendocrine organs.

The hypothalamus and the anterior pituitary are two out of the three endocrine glands that are important in cell signaling. They are both part of the HPA axis which is known to play a role in cell signaling in the nervous system.

Hypothalamus: The hypothalamus is a key regulator of the autonomic nervous system. The endocrine system has three sets of endocrine outputs which include the magnocellular system, the parvocellular system, and autonomic intervention. The magnocellular is involved in the expression of oxytocin or vasopressin. The parvocellular is involved in controlling the secretion of hormones from the anterior pituitary.

Anterior Pituitary: The main role of the anterior pituitary gland is to produce and secrete tropic hormones. Some examples of tropic hormones secreted by the anterior pituitary gland include TSH, ACTH, GH, LH, and FSH.

Endocrine cells

There are many types of cells that make up the endocrine system and these cells typically make up larger tissues and organs that function within and outside of the endocrine system.

• Hypothalamus
• Anterior pituitary gland
• Pineal gland
• Posterior pituitary gland
  • The posterior pituitary gland is a section of the pituitary gland. This organ does not produce any hormone but stores and secretes hormones such as antidiuretic hormone (ADH) which is synthesized by supraoptic nucleus of hypothalamus and oxytocin which is synthesized by paraventricular nucleus of hypothalamus. ADH functions to help the body to retain water; this is important in maintaining a homeostatic balance between blood solutions and water. Oxytocin functions to induce uterine contractions, stimulate lactation, and allows for ejaculation.
• Thyroid gland
  • follicular cells of the thyroid gland produce and secrete T₃ and T₄ in response to elevated levels of TRH, produced by the hypothalamus, and subsequent elevated levels of TSH, produced by the anterior pituitary gland, which further regulates the metabolic activity and rate of all cells, including cell growth and tissue differentiation.
• Parathyroid gland The endocrine system can control all emotions and can control temperature.
  • Epithelial cells of the parathyroid glands are richly supplied with blood from the inferior and superior thyroid arteries and secrete parathyroid hormone (PTH). PTH acts on bone, the kidneys, and the GI tract to increase calcium reabsorption and phosphate excretion. In addition, PTH stimulates the conversion of Vitamin D to its most active variant, 1,25-dihydroxyvitamin D₃, which further stimulates calcium absorption in the GI tract.
• Thymus Gland
• Adrenal glands
  • Adrenal cortex
  • Adrenal medulla
• Pancreas
  • Pancreas contain nearly 1 to 2 million islets of Langerhans (a tissue which consists cells that secrete hormones) and acini. Acini secretes digestive enzymes.
    • Alpha cells
      • The alpha cells of the pancreas secrete hormones to maintain homeostatic blood sugar. Insulin is produced and excreted to lower blood sugar to normal levels. Glucagon, another hormone produced by alpha cells, is secreted in response to low blood sugar levels; glucagon stimulates glycogen stores in the liver to release sugar into the bloodstream to raise blood sugar to normal levels.
    • Beta cells
      • 60% of the cells present in islet of Langerhans are beta cells. Beta cells secrete insulin. Along with glucagon, insulin helps in maintaining glucose levels in our body. Insulin decreases blood glucose level ( a hypoglycemic hormone) whereas glucagon increases blood glucose level.
    • Delta cells
    • F Cells
• Ovaries
  • Granulosa cells
• Testis
  • Leydig cells

Development

Main article: Development of the endocrine system

The fetal endocrine system is one of the first systems to develop during prenatal development.

Adrenal glands

The fetal adrenal cortex can be identified within four weeks of gestation. The adrenal cortex originates from the thickening of the intermediate mesoderm. At five to six weeks of gestation, the mesonephros differentiates into a tissue known as the genital ridge. The genital ridge produces the steroidogenic cells for both the gonads and the adrenal cortex. The adrenal medulla is derived from ectodermal cells. Cells that will become adrenal tissue move retroperitoneally to the upper portion of the mesonephros. At seven weeks of gestation, the adrenal cells are joined by sympathetic cells that originate from the neural crest to form the adrenal medulla. At the end of the eighth week, the adrenal glands have been encapsulated and have formed a distinct organ above the developing kidneys. At birth, the adrenal glands weigh approximately eight to nine grams (twice that of the adult adrenal glands) and are 0.5% of the total body weight. At 25 weeks, the adult adrenal cortex zone develops and is responsible for the primary synthesis of steroids during the early postnatal weeks.

Thyroid gland

The thyroid gland develops from two different clusterings of embryonic cells. One part is from the thickening of the pharyngeal floor, which serves as the precursor of the thyroxine (T₄) producing follicular cells. The other part is from the caudal extensions of the fourth pharyngobranchial pouches which results in the parafollicular calcitonin-secreting cells. These two structures are apparent by 16 to 17 days of gestation. Around the 24th day of gestation, the foramen cecum, a thin, flask-like diverticulum of the median anlage develops. At approximately 24 to 32 days of gestation the median anlage develops into a bilobed structure. By 50 days of gestation, the medial and lateral anlage have fused together. At 12 weeks of gestation, the fetal thyroid is capable of storing iodine for the production of TRH, TSH, and free thyroid hormone. At 20 weeks, the fetus is able to implement feedback mechanisms for the production of thyroid hormones. During fetal development, T₄ is the major thyroid hormone being produced while triiodothyronine (T₃) and its inactive derivative, reverse T₃, are not detected until the third trimester.

Parathyroid glands

A lateral and ventral view of an embryo showing the third (inferior) and fourth (superior) parathyroid glands during the 6th week of embryogenesis

Once the embryo reaches four weeks of gestation, the parathyroid glands begins to develop. The human embryo forms five sets of endoderm-lined pharyngeal pouches. The third and fourth pouch are responsible for developing into the inferior and superior parathyroid glands, respectively. The third pharyngeal pouch encounters the developing thyroid gland and they migrate down to the lower poles of the thyroid lobes. The fourth pharyngeal pouch later encounters the developing thyroid gland and migrates to the upper poles of the thyroid lobes. At 14 weeks of gestation, the parathyroid glands begin to enlarge from 0.1 mm in diameter to approximately 1 – 2 mm at birth. The developing parathyroid glands are physiologically functional beginning in the second trimester.

Studies in mice have shown that interfering with the HOX15 gene can cause parathyroid gland aplasia, which suggests the gene plays an important role in the development of the parathyroid gland. The genes, TBX1, CRKL, GATA3, GCM2, and SOX3 have also been shown to play a crucial role in the formation of the parathyroid gland. Mutations in TBX1 and CRKL genes are correlated with DiGeorge syndrome, while mutations in GATA3 have also resulted in a DiGeorge-like syndrome. Malformations in the GCM2 gene have resulted in hypoparathyroidism. Studies on SOX3 gene mutations have demonstrated that it plays a role in parathyroid development. These mutations also lead to varying degrees of hypopituitarism.

Pancreas

The human fetal pancreas begins to develop by the fourth week of gestation. Five weeks later, the pancreatic alpha and beta cells have begun to emerge. Reaching eight to ten weeks into development, the pancreas starts producing insulin, glucagon, somatostatin, and pancreatic polypeptide. During the early stages of fetal development, the number of pancreatic alpha cells outnumbers the number of pancreatic beta cells. The alpha cells reach their peak in the middle stage of gestation. From the middle stage until term, the beta cells continue to increase in number until they reach an approximate 1:1 ratio with the alpha cells. The insulin concentration within the fetal pancreas is 3.6 pmol/g at seven to ten weeks, which rises to 30 pmol/g at 16–25 weeks of gestation. Near term, the insulin concentration increases to 93 pmol/g. The endocrine cells have dispersed throughout the body within 10 weeks. At 31 weeks of development, the islets of Langerhans have differentiated.

While the fetal pancreas has functional beta cells by 14 to 24 weeks of gestation, the amount of insulin that is released into the bloodstream is relatively low. In a study of pregnant women carrying fetuses in the mid-gestation and near term stages of development, the fetuses did not have an increase in plasma insulin levels in response to injections of high levels of glucose. In contrast to insulin, the fetal plasma glucagon levels are relatively high and continue to increase during development. At the mid-stage of gestation, the glucagon concentration is 6 μg/g, compared to 2 μg/g in adult humans. Just like insulin, fetal glucagon plasma levels do not change in response to an infusion of glucose. However, a study of an infusion of alanine into pregnant women was shown to increase the cord blood and maternal glucagon concentrations, demonstrating a fetal response to amino acid exposure.

As such, while the fetal pancreatic alpha and beta islet cells have fully developed and are capable of hormone synthesis during the remaining fetal maturation, the islet cells are relatively immature in their capacity to produce glucagon and insulin. This is thought to be a result of the relatively stable levels of fetal serum glucose concentrations achieved via maternal transfer of glucose through the placenta. On the other hand, the stable fetal serum glucose levels could be attributed to the absence of pancreatic signaling initiated by incretins during feeding. In addition, the fetal pancreatic islets cells are unable to sufficiently produce cAMP and rapidly degrade cAMP by phosphodiesterase necessary to secrete glucagon and insulin.

During fetal development, the storage of glycogen is controlled by fetal glucocorticoids and placental lactogen. Fetal insulin is responsible for increasing glucose uptake and lipogenesis during the stages leading up to birth. Fetal cells contain a higher amount of insulin receptors in comparison to adults cells and fetal insulin receptors are not downregulated in cases of hyperinsulinemia. In comparison, fetal haptic glucagon receptors are lowered in comparison to adult cells and the glycemic effect of glucagon is blunted. This temporary physiological change aids the increased rate of fetal development during the final trimester. Poorly managed maternal diabetes mellitus is linked to fetal macrosomia, increased risk of miscarriage, and defects in fetal development. Maternal hyperglycemia is also linked to increased insulin levels and beta cell hyperplasia in the post-term infant. Children of diabetic mothers are at an increased risk for conditions such as: polycythemia, renal vein thrombosis, hypocalcemia, respiratory distress syndrome, jaundice, cardiomyopathy, congenital heart disease, and improper organ development.

Gonads

Main article: Development of the gonads

The reproductive system begins development at four to five weeks of gestation with germ cell migration. The bipotential gonad results from the collection of the medioventral region of the urogenital ridge. At the five-week point, the developing gonads break away from the adrenal primordium. Gonadal differentiation begins 42 days following conception.

Male gonadal development

For males, the testes form at six fetal weeks and the sertoli cells begin developing by the eight week of gestation. SRY, the sex-determining locus, serves to differentiate the Sertoli cells. The Sertoli cells are the point of origin for anti-Müllerian hormone. Once synthesized, the anti-Müllerian hormone initiates the ipsilateral regression of the Müllerian tract and inhibits the development of female internal features. At 10 weeks of gestation, the Leydig cells begin to produce androgen hormones. The androgen hormone dihydrotestosterone is responsible for the development of the male external genitalia.

The testicles descend during prenatal development in a two-stage process that begins at eight weeks of gestation and continues through the middle of the third trimester. During the transabdominal stage (8 to 15 weeks of gestation), the gubernacular ligament contracts and begins to thicken. The craniosuspensory ligament begins to break down. This stage is regulated by the secretion of insulin-like 3 (INSL3), a relaxin-like factor produced by the testicles, and the INSL3 G-coupled receptor, LGR8. During the transinguinal phase (25 to 35 weeks of gestation), the testicles descend into the scrotum. This stage is regulated by androgens, the genitofemoral nerve, and calcitonin gene-related peptide. During the second and third trimester, testicular development concludes with the diminution of the fetal Leydig cells and the lengthening and coiling of the seminiferous cords.

Female gonadal development

For females, the ovaries become morphologically visible by the 8th week of gestation. The absence of testosterone results in the diminution of the Wolffian structures. The Müllerian structures remain and develop into the fallopian tubes, uterus, and the upper region of the vagina. The urogenital sinus develops into the urethra and lower region of the vagina, the genital tubercle develops into the clitoris, the urogenital folds develop into the labia minora, and the urogenital swellings develop into the labia majora. At 16 weeks of gestation, the ovaries produce FSH and LH/hCG receptors. At 20 weeks of gestation, the theca cell precursors are present and oogonia mitosis is occurring. At 25 weeks of gestation, the ovary is morphologically defined and folliculogenesis can begin.

Studies of gene expression show that a specific complement of genes, such as follistatin and multiple cyclin kinase inhibitors are involved in ovarian development. An assortment of genes and proteins - such as WNT4, RSPO1, FOXL2, and various estrogen receptors - have been shown to prevent the development of testicles or the lineage of male-type cells.

Pituitary gland

The pituitary gland is formed within the rostral neural plate. The Rathke's pouch, a cavity of ectodermal cells of the oropharynx, forms between the fourth and fifth week of gestation and upon full development, it gives rise to the anterior pituitary gland. By seven weeks of gestation, the anterior pituitary vascular system begins to develop. During the first 12 weeks of gestation, the anterior pituitary undergoes cellular differentiation. At 20 weeks of gestation, the hypophyseal portal system has developed. The Rathke's pouch grows towards the third ventricle and fuses with the diverticulum. This eliminates the lumen and the structure becomes Rathke's cleft. The posterior pituitary lobe is formed from the diverticulum. Portions of the pituitary tissue may remain in the nasopharyngeal midline. In rare cases this results in functioning ectopic hormone-secreting tumors in the nasopharynx.

The functional development of the anterior pituitary involves spatiotemporal regulation of transcription factors expressed in pituitary stem cells and dynamic gradients of local soluble factors. The coordination of the dorsal gradient of pituitary morphogenesis is dependent on neuroectodermal signals from the infundibular bone morphogenetic protein 4 (BMP4). This protein is responsible for the development of the initial invagination of the Rathke's pouch. Other essential proteins necessary for pituitary cell proliferation are Fibroblast growth factor 8 (FGF8), Wnt4, and Wnt5. Ventral developmental patterning and the expression of transcription factors is influenced by the gradients of BMP2 and sonic hedgehog protein (SHH). These factors are essential for coordinating early patterns of cell proliferation.

Six weeks into gestation, the corticotroph cells can be identified. By seven weeks of gestation, the anterior pituitary is capable of secreting ACTH. Within eight weeks of gestation, somatotroph cells begin to develop with cytoplasmic expression of human growth hormone. Once a fetus reaches 12 weeks of development, the thyrotrophs begin expression of Beta subunits for TSH, while gonadotrophs being to express beta-subunits for LH and FSH. Male fetuses predominately produced LH-expressing gonadotrophs, while female fetuses produce an equal expression of LH and FSH expressing gonadotrophs. At 24 weeks of gestation, prolactin-expressing lactotrophs begin to emerge.

Function

See also: List of human endocrine organs and actions

Hormones

Main article: Hormone

A hormone is any of a class of signaling molecules produced by cells in glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour. Hormones have diverse chemical structures, mainly of 3 classes: eicosanoids, steroids, and amino acid/protein derivatives (amines, peptides, and proteins). The glands that secrete hormones comprise the endocrine system. The term hormone is sometimes extended to include chemicals produced by cells that affect the same cell (autocrine or intracrine signalling) or nearby cells (paracrine signalling).

Hormones are used to communicate between organs and tissues for physiological regulation and behavioral activities, such as digestion, metabolism, respiration, tissue function, sensory perception, sleep, excretion, lactation, stress, growth and development, movement, reproduction, and mood.

Hormones affect distant cells by binding to specific receptor proteins in the target cell resulting in a change in cell function. This may lead to cell type-specific responses that include rapid changes to the activity of existing proteins, or slower changes in the expression of target genes. Amino acid–based hormones (amines and peptide or protein hormones) are water-soluble and act on the surface of target cells via signal transduction pathways; steroid hormones, being lipid-soluble, move through the plasma membranes of target cells to act within their nuclei.

Cell signalling

The typical mode of cell signalling in the endocrine system is endocrine signaling, that is, using the circulatory system to reach distant target organs. However, there are also other modes, i.e., paracrine, autocrine, and neuroendocrine signaling. Purely neurocrine signaling between neurons, on the other hand, belongs completely to the nervous system.

Autocrine

Main article: Autocrine signalling

Autocrine signaling is a form of signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on the same cell, leading to changes in the cells.

Paracrine

Main article: Paracrine signalling

Some endocrinologists and clinicians include the paracrine system as part of the endocrine system, but there is not consensus. Paracrines are slower acting, targeting cells in the same tissue or organ. An example of this is somatostatin which is released by some pancreatic cells and targets other pancreatic cells.

Juxtacrine

Main article: Juxtacrine signalling

Juxtacrine signaling is a type of intercellular communication that is transmitted via oligosaccharide, lipid, or protein components of a cell membrane, and may affect either the emitting cell or the immediately adjacent cells.

It occurs between adjacent cells that possess broad patches of closely opposed plasma membrane linked by transmembrane channels known as connexons. The gap between the cells can usually be between only 2 and 4 nm.

Clinical significance

Disease

Main article: Endocrine diseases

Diseases of the endocrine system are common, including conditions such as diabetes mellitus, thyroid disease, and obesity. Endocrine disease is characterized by misregulated hormone release (a productive pituitary adenoma), inappropriate response to signaling (hypothyroidism), lack of a gland (diabetes mellitus type 1, diminished erythropoiesis in chronic kidney failure), or structural enlargement in a critical site such as the thyroid (toxic multinodular goitre). Hypofunction of endocrine glands can occur as a result of loss of reserve, hyposecretion, agenesis, atrophy, or active destruction. Hyperfunction can occur as a result of hypersecretion, loss of suppression, hyperplastic or neoplastic change, or hyperstimulation.

Endocrinopathies are classified as primary, secondary, or tertiary. Primary endocrine disease inhibits the action of downstream glands. Secondary endocrine disease is indicative of a problem with the pituitary gland. Tertiary endocrine disease is associated with dysfunction of the hypothalamus and its releasing hormones.

As the thyroid, and hormones have been implicated in signaling distant tissues to proliferate, for example, the estrogen receptor has been shown to be involved in certain breast cancers. Endocrine, paracrine, and autocrine signaling have all been implicated in proliferation, one of the required steps of oncogenesis.

Other common diseases that result from endocrine dysfunction include Addison's disease, Cushing's disease and Graves' disease. Cushing's disease and Addison's disease are pathologies involving the dysfunction of the adrenal gland. Dysfunction in the adrenal gland could be due to primary or secondary factors and can result in hypercortisolism or hypocortisolism. Cushing's disease is characterized by the hypersecretion of the adrenocorticotropic hormone (ACTH) due to a pituitary adenoma that ultimately causes endogenous hypercortisolism by stimulating the adrenal glands. Some clinical signs of Cushing's disease include obesity, moon face, and hirsutism. Addison's disease is an endocrine disease that results from hypocortisolism caused by adrenal gland insufficiency. Adrenal insufficiency is significant because it is correlated with decreased ability to maintain blood pressure and blood sugar, a defect that can prove to be fatal.

Graves' disease involves the hyperactivity of the thyroid gland which produces the T3 and T4 hormones. Graves' disease effects range from excess sweating, fatigue, heat intolerance and high blood pressure to swelling of the eyes that causes redness, puffiness and in rare cases reduced or double vision.

DALY rates

Disability-adjusted life year for endocrine disorders per 100,000 inhabitants in 2002.

  No data

  Less than 80

  80–160

  160–240

  240–320

  320–400

  400–480

  480–560

  560–640

  640–720

  720–800

  800–1000

  More than 1000

A DALY (Disability-Adjusted Life Year) is a measure that reflects the total burden of disease. It combines years of life lost (due to premature death) and years lived with disability (adjusted for the severity of the disability). The lower the DALY rates, the lower the burden of endocrine disorders in a country.

The map shows that large parts of Asia have lower DALY rates (pale yellow), suggesting that endocrine disorders have a relatively low impact on overall health, whereas some countries in South America and Africa (specifically Suriname and Somalia) have higher DALY rates (dark orange to red), indicating a higher disease burden from endocrine disorders.

Other animals

A neuroendocrine system has been observed in all animals with a nervous system and all vertebrates have a hypothalamus–pituitary axis. All vertebrates have a thyroid, which in amphibians is also crucial for transformation of larvae into adult form. All vertebrates have adrenal gland tissue, with mammals unique in having it organized into layers. All vertebrates have some form of a renin–angiotensin axis, and all tetrapods have aldosterone as a primary mineralocorticoid.

Pair production

From Wikipedia, the free encyclopedia

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

 

Light–matter interaction

Pair production is the creation of a subatomic particle and its antiparticle from a neutral boson. Examples include creating an electron and a positron, a muon and an antimuon, or a proton and an antiproton. Pair production often refers specifically to a photon creating an electron–positron pair near a nucleus. As energy must be conserved, for pair production to occur, the incoming energy of the photon must be above a threshold of at least the total rest mass energy of the two particles created. Conservation of energy and momentum are the principal constraints on the process. All other conserved quantum numbers (angular momentum, electric charge, lepton number) of the produced particles must sum to zero – thus the created particles shall have opposite values of each other. For instance, if one particle has electric charge of +1 the other must have electric charge of −1, or if one particle has strangeness of +1 then another one must have strangeness of −1.

The probability of pair production in photon–matter interactions increases with photon energy and also increases approximately as the square of the atomic number (number of protons) of the nearby atom.

Photon to electron and positron

Diagram showing the process of electron–positron pair production. In reality the produced pair are nearly collinear. The black dot labelled 'Z' represents an adjacent atom, with atomic number Z.

For photons with high photon energy (MeV scale and higher), pair production is the dominant mode of photon interaction with matter. These interactions were first observed in Patrick Blackett's counter-controlled cloud chamber, leading to the 1948 Nobel Prize in Physics. If the photon is near an atomic nucleus, the energy of a photon can be converted into an electron–positron pair:

(Z+)γ → e⁻
 + e⁺

Plot of photon energies calculated for a given element (atomic number Z) at which the cross section value for the process on the right becomes larger than the cross section for the process on the left. For calcium (Z=20), Compton scattering starts to dominate at hυ=0.08 MeV and ceases at 12 MeV.

Subatomic particle pair production

The photon's energy is converted to particle mass in accordance with Einstein's equation, E = mc²; where E is energy, m is mass and c is the speed of light. The photon must have higher energy than the sum of the rest mass energies of an electron and positron (2 × 511 keV = 1.022 MeV, resulting in a photon wavelength of 1.2132 pm) for the production to occur. (Thus, pair production does not occur in medical X-ray imaging because these X-rays only contain ~ 150 keV.) The photon must be near a nucleus in order to satisfy conservation of momentum, as an electron–positron pair produced in free space cannot satisfy conservation of both energy and momentum. Because of this, when pair production occurs, the atomic nucleus receives some recoil. The reverse of this process is electron–positron annihilation.

Basic kinematics

These properties can be derived through the kinematics of the interaction. Using four vector notation, the conservation of energy–momentum before and after the interaction gives:

${\displaystyle p_{\gamma }=p_{{\text{e}}^{-}}+p_{{\text{e}}^{+}}+p_{\text{ʀ}}}$

where ${\displaystyle p_{\text{ʀ}}}$ is the recoil of the nucleus. Note the modulus of the four vector

${\displaystyle A\equiv (A^0,\mathbf{A})}$

is

${\displaystyle A^2=A^{\mu }{A}_{\mu }=-(A^0{)}^2+\mathbf{A}\cdot \mathbf{A}}$

which implies that ${\displaystyle (p_{\gamma }{)}^2=0}$ for all cases and ${\displaystyle (p_{{\text{e}}^{-}}{)}^2=-m_{\text{e}}^2{c}^2}$. We can square the conservation equation

${\displaystyle (p_{\gamma }{)}^2=(p_{{\text{e}}^{-}}+p_{{\text{e}}^{+}}+p_{\text{ʀ}}{)}^2}$

However, in most cases the recoil of the nucleus is small compared to the energy of the photon and can be neglected. Taking this approximation of ${\displaystyle p_R\approx 0}$ and expanding the remaining relation

${\displaystyle (p_{\gamma }{)}^2\approx (p_{{\text{e}}^{-}}{)}^2+2p_{{\text{e}}^{-}}{p}_{{\text{e}}^{+}}+(p_{{\text{e}}^{+}}{)}^2}$

${\displaystyle -2m_{\text{e}}^2{c}^2+2\left(-\frac{E^2}{c^2}+{\mathbf{p}}_{{\text{e}}^{-}}\cdot {\mathbf{p}}_{{\text{e}}^{+}}\right)\approx 0}$

${\displaystyle 2({\gamma }^2-1)m_{\text{e}}^2{c}^2(\cos {\theta }_{\text{e}}-1)\approx 0}$

Therefore, this approximation can only be satisfied if the electron and positron are emitted in very nearly the same direction, that is, ${\displaystyle {\theta }_{\text{e}}\approx 0}$.

This derivation is a semi-classical approximation. An exact derivation of the kinematics can be done taking into account the full quantum mechanical scattering of photon and nucleus.

Energy transfer

The energy transfer to electron and positron in pair production interactions is given by

${\displaystyle (E_k^{pp}{)}_{\text{tr}}=h\nu -2m_{\text{e}}{c}^2}$

where ${\displaystyle h}$ is the Planck constant, ${\displaystyle \nu }$ is the frequency of the photon and the ${\displaystyle 2m_{\text{e}}{c}^2}$ is the combined rest mass of the electron–positron. In general the electron and positron can be emitted with different kinetic energies, but the average transferred to each (ignoring the recoil of the nucleus) is

${\displaystyle ({\overline{E}}_k^{pp}{)}_{\text{tr}}=\frac{1}{2}(h\nu -2m_{\text{e}}{c}^2)}$

Cross section

See also: Gamma ray cross section

Feynman diagram of electron–positron pair production. One must calculate multiple diagrams to get the net cross section

The exact analytic form for the cross section of pair production must be calculated through quantum electrodynamics in the form of Feynman diagrams and results in a complicated function. To simplify, the cross section can be written as:

${\displaystyle \sigma =\alpha r_{\text{e}}^2{Z}^{2}P(E,Z)}$

where ${\displaystyle \alpha }$ is the fine-structure constant, ${\displaystyle r_{\text{e}}}$ is the classical electron radius, ${\displaystyle Z}$ is the atomic number of the material, and ${\displaystyle P(E,Z)}$ is some complex-valued function that depends on the energy and atomic number. Cross sections are tabulated for different materials and energies.

In 2008 the Titan laser, aimed at a 1 millimeter-thick gold target, was used to generate positron–electron pairs in large numbers.

Astronomy

Pair production is invoked in the heuristic explanation of hypothetical Hawking radiation. According to quantum mechanics, particle pairs are constantly appearing and disappearing as a quantum foam. In a region of strong gravitational tidal forces, the two particles in a pair may sometimes be wrenched apart before they have a chance to mutually annihilate. When this happens in the region around a black hole, one particle may escape while its antiparticle partner is captured by the black hole.

Pair production is also the mechanism behind the hypothesized pair-instability supernova type of stellar explosion, where pair production suddenly lowers the pressure inside a supergiant star, leading to a partial implosion, and then explosive thermonuclear burning. Supernova SN 2006gy is hypothesized to have been a pair production type supernova.

100 Year Starship

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/100_Year_Starship 

The 100 Year Starship project (100YSS) was a one-year joint U.S. Defense Advanced Research Projects Agency (DARPA) and National Aeronautics and Space Administration (NASA) effort "to take the first step in the next era of space exploration—a journey between the stars". The study explored development of a viable and sustainable model for persistent, long-term, private-sector investment into the myriad of disciplines needed to make interstellar space travel practicable and feasible. The goal was to examine what it would take — organizationally, technically, sociologically and ethically — to develop the ability to send humans to another star within 100 years. The study culminated in a $500,000 grant awarded to a consortium under the lead of the Dorothy Jemison Foundation for Excellence, which led to the creation of an independent organization inheriting the name 100 Year Starship from DARPA. Annual 100YSS symposia were organized from 2011 to 2015, and again in 2023.

Origin

The 100 Year Starship study was conceived in the summer of 2010 by the director of the DARPA Tactical Technology Office, David Neyland, as an effort seeded by DARPA to develop a viable and sustainable model for persistent, long-term, private-sector investment into the myriad of disciplines needed to make long-distance space travel practicable and feasible. The study was intended to foster a rebirth of a sense of wonder among students, academia, industry, researchers and the general population to consider "why not" and to encourage them to tackle whole new classes of research and development related to all the issues surrounding long duration, long distance spaceflight. DARPA suggested that such research might benefit the Department of Defense and NASA, as well as the private and commercial sector. This was similar to how science fiction spurred generations of scientists and engineers to follow the career paths they did, as an avenue to capture the imagination of people who normally wouldn't think of doing research and development and tag them with something they would be excited about. The inspiration for 100YSS was the Robert Heinlein 1956 science fiction novel, Time for the Stars, in which the Long Range Foundation created technologies that took generations to deliver, but eventually benefited the entire species. Neyland assigned the Tactical Technology Office's Paul Eremenko to be the program manager and study coordinator for 100YSS. Eremenko convinced NASA Ames Research Center director Pete Worden to collaborate with DARPA on the project. DARPA funded the effort with $1M and NASA Ames provided $100k of support funding. DARPA intended to begin the yearlong 100YSS study on 1/11/11, with a gathering of visionaries for strategic planning, followed by a commercial request for proposals in the summer of 2011, then an international symposium in the fall of 2011 and finally an award of a research foundation grant in late 2011. However, Worden preempted DARPA and prematurely announced the nascent study prior to internal government coordination, at San Francisco's Long Conversation conference in October 2010. This caused considerable issue within government circles and forced DARPA to immediately follow-up with an early press release from Eremenko.

100YSS Strategic Planning Session

On January 10 & 11, 2011, DARPA gathered 30 scientists, entrepreneurs and science fiction writers in a two-day by-invitation-only brainstorming session in northern California, at Cavallo Point, near San Francisco, to chart the course for the 100 Year Starship study. The agenda consisted of cycling through the "why, what, and how" to create an organization that could sustain research that could lead to the creation of a starship in roughly 100 years.

Non-affiliated attendees included:

• Elizabeth Bear (science fiction writer)
• Jim Benford (Microwave Sciences)
• Peter Diamandis (Xprize Foundation, facilitator for the 100YSS Strategic Planning Session)
• Lou Friedman (Planetary Society [retired])
• Joe Haldeman (science fiction writer)
• Barbara Marx Hubbard (Foundation for Conscious Evolution)
• Mae Jemison (Former Astronaut, active in various educational endeavors)
• Harry Kloor (Chief science advisor for the X Prize organization)
• Marc Millis (Tau Zero Foundation)
• Alexander Rose (Long Now Foundation)
• Jack Sarfatti (StarDrive.org)
• Dan Sherkow (Global Universal Entertainment)
• Jill Tarter (Search for Extraterrestrial Intelligence – SETI Inst.)
• Jacques Vallée (Euro-America Ventures & Co-developer of ARPANET [led to Internet])
• Craig Venter (J. Craig Venter Institute, first to sequence the human genome)
• Claudia Welss (Assistant to Barbara Marx Hubbard)

DARPA attendees:

• David Neyland (Progenitor of 100YSS, director of the DARPA Tactical Technology Office)
• Paul Eremenko (coordinator and program manager for 100YSS)
• Roger Hall (DARPA space systems program manager)

NASA attendees:

• Pete Worden (NASA-Ames Director)
• Jay Falker (NASA-HQ & NIAC lead)
• Rachel Hoover (NASA-Ames, Public Affairs)
• Peter Klupar (NASA-Ames)
• Larry Lemke (NASA-Ames)
• Creon Levit (NASA-Ames – assigned to lead this 100-yr study)
• Lisa Lockyer (NASA-Ames)
• Alex MacDonald (NASA-Ames)
• Dawn McIntosh (NASA-Ames – on temporary assignment to DARPA for 100YSS)
• Alen Weston (NASA-Ames)
• Matt Daniels (NASA-Ames & Stanford PhD student)

A majority of participants agreed on three immediate-term issues associated with the creation of a new organization or foundation of this nature: intellectual property (IP), credibility, and leadership and governance.

100YSS Request for Information and Solicitation

On May 3, 2011, DARPA released a Request for Information (RFI) seeking ideas for an organization, business model and approach appropriate for a self-sustaining investment vehicle in support of the 100 Year Starship Study.

Attributes of interest in the RFI included:

• Long-term survivability over a century-long time horizon;
• Self-governance, independent of government participation or oversight;
• Self-sustainment, independent of government funding; and
• Relevance to the goal of moving humanity toward the goal of interstellar travel, including related technological, biological, social, economic, and other issues.

Respondents to the RFI needed to describe an organization and approach for the establishment and operation of the 100 Year Starship research entity (or foundation):

• Organizational structure;
• Governance mechanism;
• Investment strategy and criteria; and
• Business model for long-term self-sustainment.

DARPA received over 150 responses to the RFI.

The RFI was followed on August 26, 2011 by formal solicitation for award of a grant. To meet the needs of the August 26th solicitation DARPA planned to award in the late fall 2011 a single entity, organization or foundation a grant for initial startup, operating expenses and initial intellectual property.

100 Year Starship Symposia

On June 15, 2011, DARPA announced the 100 Year Starship Study Public Symposium, organized by DARPA's Tactical Technology Office director, David Neyland, with NASA Ames serving as execution agent. DARPA planned to encourage dialog about "all the aspects of interstellar flight ... hoping that ethicists, lawyers, science fiction writers, technologists and others, will participate." DARPA contended that the "useful, unanticipated consequences of such research – benefits from improved propulsion to energy storage and life support – can ultimately benefit the Department of Defense and to NASA, as well as the private and commercial sector."

DARPA and NASA solicited papers for the symposium on topics including:

• Time-Distance Solutions [propulsion, time/space manipulation and/or dilation, near speed of light navigation, faster than light navigation, observations and sensing at near speed of light or faster than light]
• Education, Social, Economic and Legal Considerations [education as a mission, who goes, who stays, to profit or not, economies in space, communications back to earth, political ramifications, round-trip legacy investments and assets left behind]
• Philosophical, and Religious Considerations [why go to the stars, moral and ethical issues, implications of finding habitable worlds, implications of finding life elsewhere, implications of being left behind]
• Biology and Space Medicine [physiology in space, psychology in space, human life suspension (e.g., cryogenic), medical facilities and capabilities in space, on-scene (end of journey) spawning from genetic material]
• Habitats and Environmental Science [to have gravity or not, space and radiation effects, environmental toxins, energy collection and use, agriculture, self-supporting environments, optimal habitat sizing]
• Destinations [criteria for destination selection, what do you take, how many destinations and missions, probes versus journeys of faith]
• Communication of the Vision [storytelling as a means of inspiration, linkage between incentives, payback and investment, use of movies, television and books to popularize long term research and long term journeys]

Three days prior to the start of the Symposium, then director of DARPA, Dr. Regina E. Dugan, and her deputy, Dr Kaighan (Ken) Gabriel, discussed the plan and intent of the symposium with Neyland and requested he cancel the entire event. Neyland explained how visible and public it was, with world travelers already en route to attend. He suggested that cancelling would have a more negative impact than letting it happen. Dugan and Gabriel agreed to let the symposium proceed, but required removal of all DARPA and NASA logos and emblems, as well as curtailing participation by DARPA personnel. They also insisted that no public video, audio recordings or photography would be allowed, and no proceedings or papers would be officially published.

The symposium was held in Orlando, Florida, from September 30 to October 2, 2011. It included presentations on the technology, biology, physics, philosophy, sociology, and economics of interstellar flight. More than 500 papers were submitted and more than 700 people attended. Select papers from the conference were published in the Journal of the British Interplanetary Society.

Neyland, who orchestrated the one-year starship study, provided the welcome and introduction at the Symposium, but no other DARPA personnel spoke. No high-level NASA officials spoke at the symposium either, other than Pete Worden, director of the NASA Ames Research Center in California, whom Neyland described as a "co-conspirator" and who was often regarded as a maverick in the space agency.

In 2012, after the Jemison Foundation was named as the winner of the DARPA 100YSS grant, it organized the second symposium in Houston. Papers on many subjects related to interstellar flight and organizational foundations were presented. In 2013 and 2014 symposia were held in Houston, and a fifth in November 2015. The sixth symposium was held in Nairobi, Kenya from January 31-February 4, 2023.

100YSS Intellectual Property

By design, DARPA invested in the instruments of intellectual property to support the eventual selection of an organization to carry the 100YSS vision forward. DARPA established and copyrighted the 100YSS.org website and trademarked the original names, acronyms, logos and artwork. At the award of the 100YSS grant, 100YSS intellectual property rights and trademarks were passed in perpetuity to the new 100YSS organization.

Foundation

The 100 Year Starship study was the name of the one-year DARPA project to explore development of a viable and sustainable model for persistent, long-term, private-sector investment into the myriad of disciplines needed to make interstellar space travel practicable and feasible. The outcome of the study was the selection of an organization to carry the vision forward. The winning bid was the Dorothy Jemison Foundation for Excellence, partnering with Icarus Interstellar and the Foundation for Enterprise Development, led by the American physician and former NASA astronaut Mae Jemison. In 2012, the consortium was awarded a $500,000 grant for further work. The new organization was granted the 100YSS intellectual property from DARPA and maintained the organizational name 100 Year Starship. It was planned that the Dorothy Jemison Foundation for Excellence would team up with Icarus Interstellar, where the latter would work on the technical challenges of 100YSS.

After the Jemison Foundation was named as the winner of the grant, it organized the second symposium in Houston. Papers on many subjects related to interstellar flight and organizational foundations were presented. In 2013 and 2014 symposia were also held in Houston, and a fifth was held in Austria in November 2015.

Canopus Awards

2015 Canopus Awards

In 2015, the 100 Year Starship project hosted its first Canopus Awards for excellence in interstellar writing. The winners were announced October 30, 2015, at the symposium:

• Previously Published Long-Form Fiction (40,000 words or more): InterstellarNet: Enigma by Edward M. Lerner (FoxAcre). ISBN 978-1936771646
• Previously Published Short-Form Fiction (1,000–40,000 words): "The Waves" by Ken Liu (Asimov's 12/12)
• Original Fiction (1,000–5,000 words): "Everett's Awakening" by Yelcho (i.e., R. Buckalew)
• Original Nonfiction (1,000–5,000 words): "Finding Earth 2.0 from the Focus of the Solar Gravitational Lens" by Louis Friedman and Slava Turyshev

2017 Canopus Awards

A second Canopus Award competition was run in 2017. The winners were:

• Previously Published Long-Form Fiction (40,000 words or more): The Three-Body Problem, by Liu Cixin, translated by Ken Liu (published by Tor)
• Previously Published Short-Form Fiction (1,000–40,000 words): "Slow Bullets" by Alastair Reynolds (published by Tachyon Publications)
• Previously Published Nonfiction (1,000–40,000 words): Welcome to Mars: Making a Home on the Red Planet, by Buzz Aldrin and Marianne Dyson (published by National Geographic)
• Original Fiction (1,000–5,000 words): "The Quest for New Cydonia" by Russell Hemmell
• Original Nonfiction (1,000–5,000 words): "Microbots—The Seeds of Interstellar Civilization" by Robert Buckalew
• Original College Writing (1,000–5,000 words): "A Kingdom of Ends" by Ryan Burgess

2023 Canopus Awards

A third Canopus Award competition has been announced for 2023. A new category, "Original Local Short-form Fiction," open to continental African writers, was introduced for the 2023 award. The finalists, by category, are:

• Published Long-Form Fiction:
  • Escaping Exodus by Nicky Drayden (published by HarperVoyager)
  • Light Chaser by Peter F. Hamilton and Gareth L. Powell (published by Tor)
  • Sweep of Stars by Maurice Broaddus (published by Tor)
  • Braking Day by Adam Oyebanji (published by DAW)
  • Project Hail Mary by Andy Weir (published by Ballantine Books)
  • Sentient by Jeff Lemire and Gabriel Hernandez Walta (published by TKO)
• Published Short-Form Fiction:
  • "Drift-Flux" by Wole Talabi (published in AfroSFv3)
  • "Verisya" by Mari Ness (published in Daily Science Fiction)
  • "Repairs at the Beijing West Space Elevator" by Alex Shvartsman (published in Analog Science Fiction & Fact)
  • "A Sun Will Always Sing" by Karin Lowachee (published in TheVerge.com)
  • "Generations" by Osahon Ize-Iyamu (published in Bikes Not Rockets)
  • "The Hind" by Kevin J. Anderson and Rick Wilber (published in Asimov's Science Fiction)
  • "Tau Ceti Said What?" by Jack McDevitt (published in Asimov's Science Fiction)
• Published Long-Form Nonfiction:
  • A Traveler's Guide to the Stars by Les Johnson (published by Princeton University Press)
  • Extraterrestrial by Avi Loeb (published by Mariner Books)
  • Imagined Life by James Trefil and Michael Summers (published by Smithsonian Books)
  • The Case for Space: How the Revolution in Spaceflight Opens Up a Future of Limitless Possibility by Robert Zubrin (published by Prometheus)
  • Starship Citizens: Indigenous Principles for 100 Year Interstellar Voyages by Dawn Marsden (published by Wood Lake Publishing)
• Published Short-Form Nonfiction:
  • "Language Development During Interstellar Travel" by A. McKenzie and J. Punske (published in Acta Futura)
  • "Artificial Intelligence for Interstellar Travel" by Andreas M. Hein and Stephen Baxter (published in the Journal of the British Interplanetary Society)
  • "Navigation and Star Identification for an Interstellar Mission" by Paul McKee, Jacob Kowalski, and John A. Christian (published in Acta Astronautica)
  • "Joining the 'Galactic Club': What Price Admission? A Hypothetical Case Study of the Impact of Human Rights on a Future Accession of Humanity to Interstellar Civilization Networks" by Michael Bohlander (published in Futures)
  • "Migrating Extraterrestrial Civilizations and Interstellar Colonization: Implications for SETI and SETA" by Irina K. Romanovskaya (published in the International Journal of Astrobiology)
• Published Digital Presentation:
  • Space Haven by Bugbyte LTD. (published by Bugbyte LTD.)
  • The Outer Worlds by Obsidian Entertainment (published by Private Division)
  • Ixion by Bulwark Studios (published by Kasedo Games)
  • Colony Ship by Iron Tower Studio (published by Iron Tower Studio)
  • The Sights of Space: A Voyage to Alien Worlds by MelodySheep (published by MelodySheep)
  • The Fermi Paradox by Anomaly Games (published by Anomaly Games)
• Original Short-Form Fiction:
  • "Tess 16201c" by Faith Guptill
  • "Ortygia" by Scott Jessop
  • "The Interlopers" by Robert Buckalew
  • "We Should Have Guessed" by Terry Franklin
  • "The Living Archaeologist" by Jamiella Brooks
• Original Local Short-Form Fiction:
  • "Gumbojena" by Chioniso Tsikisayi (Zimbabwe)
  • "Space Frenemies" by Oluwatoyin Magbagbeola (Nigeria)
  • "One More Chance" by Chioma Mildred Okonkwo (Nigeria)
• "Incubation" by Amadin Ogbewe (Nigeria)

Criticism

The 100 Year Starship was named in 2012 by U.S. Senator Tom Coburn as one of the 100 most wasteful government spending projects. Coburn specifically cited a 100 Year Starship workshop that included one session, titled "Did Jesus Die for Klingons Too?" that debated the implications for Christian philosophy should life be found on other planets.

Multipotentiality

From Wikipedia, the free encyclopedia

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

Multipotentiality is an educational and psychological term referring to the ability and preference of a person, particularly one of strong intellectual or artistic curiosity, to excel in two or more different fields.

It can also refer to an individual whose interests span multiple fields or areas, rather than being strong in just one. Such traits are called multipotentialities, while "multipotentialites" has been suggested as a name for those with this trait.

By contrast, those whose interests lie mostly within a single field are called "specialists".

History

Etymology

An early instance of the term in the record comes from relevant research in giftedness.

In 1972, R.H. Frederickson et al. defined a multipotentialed person as someone who, "when provided with appropriate environments, can select and develop a number of competencies to a high level".

On October 22, 2008, Douglas Hannay began a blog that lasted some eight years. His first blog referred to multipotentializing as excelling in multiple fields of energy. The blog was then copied in its entirety to Facebook on September 22, 2016, after viewing Emilie Wapnick's TED talk on being a multipotentialite during October 2015.

In 2010, multipotentiality appeared again in Tamara Fisher's article in Education Week. She defines it thus:

Multipotentiality is the state of having many exceptional talents, any one or more of which could make for a great career for that person.

— Tamara Fisher, Education Week

During 2015, Emilie Wapnick coined the term "multipotentialite", perhaps to establish a shared identity for the community. They define it this way:

A multipotentialite is someone with many interests and creative pursuits.

Although multipotentialite is a modern term, the idea of someone with many passions is not new. Any student of history often hears mention of polymaths or Renaissance people. Multipotentialites have, indeed, existed as long as human societies.

While the strengths of multipotentialites are not always appreciated in post-industrial capitalist societies, there have been times throughout history when being well-versed in multiple disciplines was considered the ideal. And, of course, multipotentiality is highly valued in certain spaces, contexts and cultures today.

When multipotentialites are supported and encouraged to embrace their diverse skills and experiences, they're able to tap into their super powers: idea synthesis, rapid learning, adaptability, big picture thinking, relating to and translating between different types of people, "languages", and modes of thought.

The ability to draw from and integrate a range of diverse ideas makes multipotentialites particularly well-suited to solving complex, multifactorial problems. And, their unconventional backgrounds help them develop unique voices and contribute fresh perspectives wherever they go.

— Emilie Wapnick, Terminology, Puttylike

Relevant terminology

While the term "multipotentialite" is often used interchangeably with polymath or Renaissance Person, the terms are not identical. One need not be an expert in any particular field to be a multipotentialite.

Indeed, Isis Jade  makes a clear distinction between multipotentiality and polymaths. Multipotentiality refers simply to one's potential in multiple fields owing to his/her diverse interests and attempts. Polymaths, on the other hand, are distinguished by their mastery and expertise in several fields. In this sense, multipotentialites can be viewed as potential polymaths.

Other terms used to refer to multipotentialites are "scanners", "slashers", "generalist", "multipassionate", "RP2", and "multipods", among others.

Context

With the advent of the industrial age, cultural norms have shifted in favor of specialization. Indeed, in the modern day, the more narrow the specialization, the higher the pay and respect accorded, for example: PhD graduates, and specialized lawyers, doctors, and engineers. The aphorism Jack of all trades, master of none emphasizes this. Older emphasis towards generalism and multiple potentials such as Renaissance humanism and the Renaissance man were replaced.

However, the convergence economy, Internet age, connectivity, the rise of the Creative Class, and other modern developments are bringing about a return of a more positive opinion for generalists and multipotentialites.

In Specialization, Polymaths And The Pareto Principle In A Convergence Economy, Jake Chapman writes:

Economists tell us that the history of human labor is one of continually increasing specialization. In the days of the hunter-gatherer, every member of the tribe would have been expected to command some degree of proficiency with each task.

As we progressed along the economic continuum from hunter-gatherer through agrarian and industrial and now into post-industrial economies, the labor force has become more fragmented, with workers having more and more specialized skill sets. ... Historically, specialization has been a path to prosperity. Although specialization has certain economic advantages, in the era of technological convergence, well-educated generalists will be those who are the most valuable. It is time for a renaissance of the "Renaissance Man". ... The Renaissance thinkers recognized both the potential of individuals as well as the enormous value to being well-rounded. Unfortunately, somewhere along the way the idea of someone who dabbled in many fields lost its cultural appeal and we began to praise those who sought deep subject matter expertise.

We now live in a world where distinctions between formerly separate industries are breaking down and the real opportunities for growth are where those industries intersect. Harnessing these 21st-century opportunities will require people who are "jacks of all trades, masters of none", or, perhaps more accurately, master polymaths.

— Jake Chapman

Business

Organizations such as startups that require adaptability and holding multiple roles can employ several multipotentialites and have one specialist as a resource.

In Specialization, Polymaths And The Pareto Principle In A Convergence Economy, Chapman said:

In the modern world, where a very common job might require someone to be a social-media expert, public speaker, writer and data analyst, the polymath wins and the deep subject-matter expert is relegated to a back corner to be used as a resource for others. As an investor, if I were going to pick the perfect team, it would be a group of rock-star polymaths with a single subject matter expert as a resource.

— Jake Chapman, In Specialization, Polymaths And The Pareto Principle In A Convergence Economy

Stretch Magazine discusses the role of multipotentialites in organizations and how they will believe they will be more in demand in the future.

Criticism of specialization

Historical context, current conventional wisdom, comparative advantage, USP, among others contribute to the wide acceptance of specialization.

Proponents of specialization above cite excellence and its perceived higher rewards compared to mediocrity in everything. Proponents of multiple capabilities below emphasize the importance of adaptability.

In "Master of Many Trades", Robert Twigger goes so far as to coin the word "monopath": "It means a person with a narrow mind, a one-track brain, a bore, a super-specialist, an expert with no other interests — in other words, the role-model of choice in the Western world."

This sentiment is not new. In Time Enough for Love (1973), Robert A. Heinlein wrote:

A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.

— Robert A. Heinlein, Time Enough for Love

In an article on the decline of polymathy, Felipe Fernández-Armesto wrote, "Universities bear some responsibility for its extinction. Classical Greece, Renaissance Italy and Victorian England all revered and rewarded generalists, for whom today universities have little or no space or patience. Enclosed departments in discrete spaces, with their own journals and jargons, are a legacy of lamentable, out-of-date ways of organising knowledge and work."

Impact

In a world that overvalues specialization, the term and its increasing popularity (especially among the blogging community) have contributed to the revival of awareness on the importance of generalists. It was even used in a competition's training session.

In the current economy, Creativity and the rise of the Creative Class are linked to divergent thinking and innovative solutions to current problems. Because new ideas can be found in the intersection of multiple fields, they would benefit from the advantages of multipotentialites.