Gravitational waves and their sources in the Universe
V. Antonuccio
INAF, Catania Astrophysical Observatory, ITALY
[email protected]
1. Which phenomena produce Gravitational waves? What's the
difference between GWs and electromagnetic waves (light)?
2. Theory of General Relativity: Space-time in 4 dimensions
3.Gravitational waves generation: hands-on formulae
4.Gravitational waves and the "ontology of 4D spacetime"
Space-time exists!
• The discovery of GWs has an immediate consequence: 4dimensional Space-Time of Einstein exists: it is a physical
object
Space-time exists!
• The discovery of GWs has an immediate consequence: 4dimensional Space-Time of Einstein exists: it is a physical
object
• In Newtonian mechanics, space is 3-dimensional and infinite
in extent, time is eternal and flows always in one direction.
Space-time exists!
• The discovery of GWs has an immediate consequence: 4dimensional Space-Time of Einstein exists: it is a physical
object
• In Newtonian mechanics, space is 3-dimensional and infinite
in extent, time is eternal and flows always in one direction.
• Newton: Space is just a container of events, and time is
independent.
Space-time exists!
• The discovery of GWs has an immediate consequence: 4dimensional Space-Time of Einstein exists: it is a physical
object
• In Newtonian mechanics, space is 3-dimensional and infinite
in extent, time is eternal and flows always in one direction.
• Newton: Space is just a container of events, and time is
independent.
Space-time exists!
• The discovery of GWs has an immediate consequence: 4dimensional Space-Time of Einstein exists: it is a physical
object
• In Newtonian mechanics, space is 3-dimensional and infinite
in extent, time is eternal and flows always in one direction.
• Newton: Space is just a container of events, and time is
independent.
• Same Spacetime as in Einstein's Special Relativity
Space-time exists!
• Einstein(1952): The "hole argument"
brings to the conclusion that:
Space-time exists!
• Einstein(1952): The "hole argument"
brings to the conclusion that:
"...On the basis of the general theory of
relativity ... space as opposed to ‘‘what
fills space’’ ...has no separate existence. ...
Space-time exists!
• Einstein(1952): The "hole argument"
brings to the conclusion that:
"...On the basis of the general theory of
relativity ... space as opposed to ‘‘what
fills space’’ ...has no separate existence. ...
There is no such thing as an empty space,
i.e., a space without a [gravitational] field.
Space-time exists!
• Einstein(1952): The "hole argument"
brings to the conclusion that:
"...On the basis of the general theory of
relativity ... space as opposed to ‘‘what
fills space’’ ...has no separate existence. ...
There is no such thing as an empty space,
i.e., a space without a [gravitational] field.
... Spacetime does not claim existence on
its own, but only as a structural quality of
the field. ..."
Space-time exists!
• Einstein(1952): The "hole argument"
brings to the conclusion that:
"...On the basis of the general theory of
relativity ... space as opposed to ‘‘what
fills space’’ ...has no separate existence. ...
There is no such thing as an empty space,
i.e., a space without a [gravitational] field.
... Spacetime does not claim existence on
its own, but only as a structural quality of
the field. ..."
• Thus, for A.E. spacetime exists only
if and where gravity is present
"Ontology" of Space-Time
• Absolutism vs. relationism
"Ontology" of Space-Time
• Absolutism vs. relationism
• Mach: Space-Time only expresses underlying relations
between matter - no independent existence
"Ontology" of Space-Time
• Absolutism vs. relationism
• Mach: Spacetime only expresses underlying relations
between matter - no independent existence
• Einstein: Gravity ↔ Spacetime
"Ontology" of Space-Time
• Absolutism vs. relationism
• Mach: Spacetime only expresses underlying relations
between matter - no independent existence
• Einstein: Gravity ↔ Spacetime
• Bachelard , "La valeur inductive de la Relativité" (1929):
analyses the new way how physical concepts are
introduced ".....dans les doctrines de la Relativité plus que
dans toute autre, l'affirmation d'une possibilité apparaît
comme antécédente à l'affirmation d'une réalité ; le
possible est alors le cadre a priori du réel. ...."