Name: escape velocity limits and black holes
Uploaded: 2025-05-22T09:05:41.000Z
Duration: 1 min 21 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Earth and Space Science

Space Systems

3.3.9-12.B

Schwarzschild Radius and Event Horizon

Un proiettile immaginario lanciato dalla superficie del Sole richiederebbe una velocità di 618 km/s per sfuggire al campo gravitazionale del Sole.
Ora, supponiamo che il raggio del Sole si riduca della metà, mantenendo costante la sua massa. Quindi la sua velocità di fuga aumenterebbe a 873 km/s. Se il raggio viene diminuito ulteriormente, alla fine a 2,9 km, la velocità di fuga sarà uguale alla velocità della luce.
Ricordiamo che la velocità di fuga di un proiettile dipende dalla massa e dal raggio dell'oggetto da cui viene lanciato.
In generale, il raggio al quale una massa ha una velocità di fuga uguale alla velocità della luce è chiamato raggio di Schwarzschild. Pertanto, il raggio di Schwarzschild è uguale al doppio del prodotto della costante gravitazionale e della massa dell'oggetto divisa per il quadrato della velocità della luce.
Qualsiasi oggetto sferico non rotante con un raggio inferiore al suo raggio di Schwarzschild è chiamato buco nero. 
La superficie sferica che circonda il buco nero, al raggio di Schwarzschild, è nota come orizzonte degli eventi, all'interno del quale la velocità di fuga è maggiore della velocità della luce.

raggio di schwarzschild e orizzonte degli eventi

Nessun oggetto con una massa finita può viaggiare più velocemente della velocità della luce nel vuoto. Questo fatto porta ad un'interessante conseguenza nell'ambito dei campi gravitazionali estremamente alti.

La velocità minima richiesta per lanciare un proiettile dalla superficie di un oggetto al quale è gravitazionalmente legato così che possa fuggire al campo gravitazionale dell'oggetto è chiamata velocità di fuga. La velocità di fuga è indipendente dalla massa dell'oggetto. Unendosi all'idea che la velocità di fuga con la massima velocità a cui la materia può viaggiare porta ai concetti di raggio di Schwarzschild, buchi neri, e orizzonte degli eventi.

Se un oggetto è sufficientemente denso, collassa su se stesso ed è circondato da un orizzonte degli eventi da cui niente può scappare. Il nome di tale oggetto è “buco nero” fu dato dall'astronomo John Wheeler nel 1969. Si riferisce al fatto che anche la luce non può fuggire a tale oggetto. Karl Schwarzschild fu la prima persona a notare questo fenomeno nel 1916, ma a quel tempo, fu considerato come una curiosità matematica.

Sebbene un buco nero non possa essere direttamente osservato perché la luce non scappa dal suo orizzonte degli eventi, c'è la prova schiacciante dell'esistenza dei buchi neri nell'universo. I loro effetti sulle stelle vicine e sulla materia in caduta sono tipicamente interpretati facendo osservazioni astronomiche.

Questo testo è adattato da <a href="https://openstax.org/books/university-physics-volume-1/pages/13-7-einsteins-theory-of-gravity">Openstax, University Physics Volume 1, Section 13.7: Einstein's Theory of Gravity.</a>

Raggio di Schwarzschild e orizzonte degli eventi

Nessun oggetto con una massa finita può viaggiare più veloce della velocità della luce nel vuoto. Questo fatto ha una conseguenza interessante nel dominio di estremamente ...

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escape velocity limits and black holes

Escape velocity helps explain how black holes and event horizons form. It is the minimum speed a projectile needs to leave the surface of an object and eventually escape its gravitational field. In this context, escape velocity does not depend on the mass of the object being launched.

The key idea is that no object with finite mass can move faster than the speed of light in a vacuum. When escape velocity is compared with that speed limit, the Schwarzschild radius becomes important. If an object is dense enough, it can collapse under its own gravity and form an event horizon. Nothing can escape from inside that boundary.

An object like this is called a black hole. The name was coined by astronomer John Wheeler in 1969, and it describes the fact that even light cannot get out. Karl Schwarzschild first described this phenomenon in 1916, but it was then treated as a mathematical curiosity.

Black holes cannot be seen directly because light does not leave the event horizon. Even so, there is strong evidence that they exist in the universe. Astronomers study their effects on nearby stars and on matter falling toward them to infer their presence.

Escape Velocity Limits and Black Holes

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Learn how escape velocity, the Schwarzschild radius, and event horizons explain why black holes trap even light and how astronomers detect them.

Escape Velocity Limits and Black Holes | JoVE K12

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3.3.9-12.D

Louisiana Student Standards for Science

High School

Earth Science

Earth’s Place In The Universe

HS-ESS1-1

HS-ESS1-2

Virginia  Standards of Learning

HIgh School

ES.2

ES.2.a

ES.2.d

Alabama Course of Study Science

Earth's Place in the Universe

9-12.ESS.1.3.b

Florida Department of Education

SC.912.E.5

SC.912.E.5.6

SC.912.E.5.10

Physical Science

SC.912.P.12

SC.912.P.12.7

Georgia Standards of Excellence

Astronomy

SAST4

SAST4.1

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3.3.9-12.A

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3.3.9-12.C

Escape Velocity Limits and Black Holes

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