1 / 22

Future of Universe

bracha
Download Presentation

Future of Universe

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Future of Universe The universe’s future depends upon how much matter is present There is a critical density of the amount of matter in the universe which will determine if the universe is going to collapse on itself or will expand forever. This is often expressed in terms of the Greek letter - omega

    2. Future of Universe The standard models give our universe three choices: Omega > 1 : Universe will collapse on itself ( closed) will end in big crunch Omega=1 : Universe will slowly stop expanding (flat) Omega <1 : Universe will continue to expand forever (open)

    3. Future of Universe

    4. Future of Universe

    5. Future of Universe But recent (within last 4 years) observations have shown that the universe is not obeying any of these models. Observations of distant Type 1a SN have shown that universe is accelerating Strangely enough this brings Einstein’s cosmological constant into play. Perhaps one of most exciting fields in physics Leading theories claim this is due to “dark energy” a force which we know less about then even dark matter.

    6. The Beginning of Time Have discussed that galaxies were formed from protogalactic clouds. What happen before that Need to examine very early universe to answer This field of astronomy is called cosmology

    7. Four Forces in Nature According to the standard model there are four forces in nature Strong Weak Electromagnetic Gravity The standard model describes three of these four but fails to describe gravity The quantum theory of gravity is one of the big problems in current research. (some ideas)

    9. First Few Minutes The Four forces were united The early universe was extremely hot So hot that the photons had enough energy such that they could collide and produce electron-positron pairs These pairs would then re-annihilate and form photons.

    10. Plank Time The first instant of time (until 10-43 s) is known as Plank time. This era was governed by quantum gravity Not understood.

    11. GUT Era After the plank time gravity became a separate force but remaining three were still united. Think gravity was “frozen out” of the unified forces Remaining three united forces termed GUT (Grand Unified Theory) Universe grew very quickly at this point (Inflation) lasted until 10-36 s universe at 1029 K.

    12. Electroweak Era Then strong force separated from the GUT force. Leaves three forces Gravity Strong Electroweak Universe at 10-15 K lasted until 10-10 s Theories are still not strong here

    13. Particle Era Finally temperature of universe lowered such that particles could be formed as shown earlier. at first only quarks and leptons. Termed quark-gluon plasma. Then around 1 millisecond protons and neutrons could form Temp drops below 1012 K.

    14. Nucleosynthesis and era of nuclei From 0.001 seconds until 3 minutes universe underwent fusion 75% of baryonic matter became 1H 25% became heavier H isotopes, He, and Li. Era of Nuclei for next 500,000 years universe cooled until galaxies could form. Era is observed today in the form of Cosmic Background radiation

    15. 3 K Background Radiation Echoes of the era of the nuclei are seen as a 3 K blackbody background curve This was first seen as “noise” by a microwave antenna by Arno Penzias and Robert Wilson at Bell Labs. Princeton scientists recognized this as redshifted light from the Big Bang. Penzias and Wilson won the Nobel Prize in 1978 for this discovery.

    16. 3 K Background Radiation This is light from when the universe was 500,000 years old It forms a perfectly uniform blackbody curve from a temp of 2.7 K which was 3,000 K when it was created but longer due to redshift. The spectrum was measured with great precision by the COBE (Cosmic Background Explorer) satellite in the 1990’s. It found that the cosmic background was extremely uniform in direction but it did have inhomogeneties in it. These inhomogeneties are fluxuations of 0.002 K to 2.7 Background These measurements are evidence of inflation (later)

    18. Cause of CBR This is light from the synthesis of He Happened as universe cooled from 1011 K to 1010 K. after about 1 minute

    19. Evidence for Big Bang Galactic redshift (universe is expanding) Cosmic Background radiation Observation of Helium which agree with the standard Big Bang model. Obler’s paradox (1800’s)- why is night sky dark?

    20. Problems with Big Bang Where does large scale structure come from Why is universe so smooth at early times? Observation - Density of universe is very close to critical. These seem to be solved if we modify the standard Big Bang model with inflation.

    21. Inflation Theory was created in 1980’s by Alan Gurth Basic Idea: Universe underwent tremendous growth (1030 times its original size) during the time when the Strong force was “frozen out” from GUT. Quantum fluxuations caused the negative pressure which forced this rapid expansion. These fluxuations are what we see as inhomogeneties in COBE’s measurements of CBR.

More Related